C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/vol_300/361_02/terms.txt

Text File | 1991-09-18 | 312.8 KB | 5,525 lines

*****************  General Technical Terms Used Locally *********************


   This information was collected to fill specific mission related local
requirements for local personnel to provide practical, working definitions
of technical terms used locally and to provide a collection/distribution
media for ATE/CAE information not elsewhere recorded.  No attempt has been
made to exhaustively define terms beyond the level required for current local
use.  Any other application of this information is beyond its intended scope
and is entirely at the user's risk.  Working definitions imply judgment
calls.  These are the personal, private, professional opinions of the editor
and in no way reflect an endorsement or condemnation by any official body.
Factual information is believed accurate and to the extent practical has been
verified.

   As is obvious from the diversity of styles, this is a compilation of
Engineering Notes, clipped published materials and training materials used
primarily for the training of COOP Students and New-Hire Engineers/Techs.
Portions of this material range back more than ten years and must be viewed
with some caution (the "half-life" of technical information is about 4
years).

  Errors and candidates for inclusion should be mailed to the system manager
(root).  Be Patient.  This is strictly a "Burn-Out" task worked on in time
otherwise not productively usable.  This information exists for training
purposes.  This file exists for testing purposes...when printed out to check
for transmission errors, dropped bits, printer/printer driver or link mal-
functions, a successfully produced hardcopy can be handed on as a training
aid...an equivalent in "The Quick Brown Fox" is scrap paper.

----------------------------------------------------------------------------
*
* Copyrighted to the Public Domain.  Unlimited Distribution Authorized.
*
* User Assumes All Risks/Liabilities.
*
----------------------------------------------------------------------------

                                    -A-

>A Law.  A weighted scale applied to audio signals on telephone circuits to
more accurately reflect "loudness".  One of two widely used weighting scales,
the other being "mu Law" or "u Law".  A scale related to the latter is the
u255 scale, a weighting scale popular in Europe.

+ABC.  Atanasoff-Berry Computer.  Established by the Courts (1973) to be the
first successful digital computer DESIGN, this machine could solve a system
of 29 linear equations in 29 unknowns to an accuracy of 15 decimal places
(more than 48 bits).  Designed in 1939 and developed into Proof-of-Concept
phase on a $5K budget (the MARK I began w/ $1 Million), the ABC included such
advanced concepts as DRAM, binary ALU and logic circuits rather than the
pulse-train/counter (Tabulator) technology of ENIAC.  A two man project,
ABC's designer was John V. Atanasoff, a professor at Iowa State University
(Ames, Ia).  Clifford Berry, a graduate student, performed the actual fabri-
cation, the results of which survive in newspaper photos published at the
time.  Letters exchanged w/ ENIAC's John Mauchy (and a visit in 1941) trans-
planted much of ABC's innovation into ENIAC.  Atanasoff did not seek patents
on his work, but Mauchy did.  Granted in 1964, invalidated in 1973, these
patents could have seriously inhibited the explosive growth of the microcom-
puter.

---> An historical note:  Special purpose electronic computers popped up in
several places around 1940, including Germany.  Except for the proposals sent
to the German Army, little remains of the "Z" computers built in Berlin.
There is evidence that a general purpose electronic digital computer was
demonstrated to the German Air Force (they didn't want it) prior to the
1943 bomb attacks that destroyed it and its creators.  Atanasoff joined the
Naval Research Laboratory (NRL) Washington, DC.  Judging by his testimony
during the UNIVAC trial, it appears his "oversight" in protecting his
invention was his way of placing his work into the Public Domain without
interference from the War Dept.

>Absolute Filter.  A dry paper filter capable of trapping particles as small
as tobacco smoke.  Used in disk drives.

>Ack/Nack.  A protocol in which the return of one of two special characters
indicates the acceptance or rejection of a block of data.

>ACM.  Association for Computing Machinery.  A worldwide organization of
Computer Scientists, Engineers and Technologists resembling the IEEE Computer
Society.  Largest of its kind, ACM yearly awards the "Turing Award" for
outstanding contributions to the state of the art in Computers.

>Acoustic Coupler.  A method of coupling modem tones to/from a telephone
hand- set without an electrical interconnection.  Now largely displaced by
Modular RJ-11 plugs and FCC registeration.

>A/D.  Analog to Digital Converter.  A class of devices that convert an input
signal into a numeric representation.  Ranges from very precise (but slow) DC
systems called "Digital Voltmeters" (DVM) to very fast (but low precision)
units called "Flash Converters", including some interesting variations such
as the Tektronix Transient Digitizer, which uses a scan conversion  (oscillo-
graphic) technique.  The basic trade-off is speed vs precision.  Higher
speeds allow the tracking of faster input signals.  Many innovative varia-
tions exist.  Most units are ranked by bits of precision, e.g., a "12 Bit A/D
Converter".

>Ada.  A general purpose DOD language designed by committee and written (in
large part) by the French firm Honeywell-Bull.  The Ada project grew from a
study showing maintenance to be the dominant lifecycle cost factor for soft-
ware (which is true).  Developed via competitive run-off through an evolving
series of performance specifications, Ada jelled about the time Pascal's
influence peaked (before actual use disclosed its labor intensive nature).
Clearly a superset of Pascal, Ada proved to be even more laborious to use.
Part of this comes from the inclusion of "Bells and Whistles" necessary to
make a single language be all things to all people.  Ada has effectively
banned the creation of tools ala 'C' or Fortran substituting a closed set of
"approved" tools.  An elaborate scheme of safeguards has been designed to
protect the programmer from errors (and himself).  These have blown compiler
implementations out of shape, making them very large, slow and expensive.
DOD plans to "validate" compilers via an "exhaustive" suite of tests and
refuses to authorize subsets of the language.  Eminent Computer Scientists
(including the winner of the 1982 ACM Tunning Award who helped design the Ada
language) seriously doubt it will ever be successfully debugged.  Ada in-
cludes constructs supporting real-time applications (such as weapons
control), a role for which it is poorly suited due to the high overhead
associated w/ its highly modular design (See Context Switching).  As the
first validated compilers came on-line (1984), DOD backed away from its
universal Ada mandate imposed earlier.  There is a very real possibility that
Ada will end up like ATLAS and previous DOD "Universal Languages" (JOVIAL,
CMS2, etc.) which are confined to a narrow range of  strictly military appli-
cations.  There is also the possibility that DOD has spent $150 Million on a
language too expensive even for it to use.

---> Update 90:  ---------- The Score Sheet on Ada -----------------------

1. Ada was Benchmarked against COBOL.  COBOL won.
2. Ada failed to win Industry converts.  Fortran & C dominate.
3. Ada failed to win University Support.  CS Students are told, "Forget Ada".
4. Ada Libraries & Programming Environments are Vaporware.
5. Full Ada Compilers are Slow and Expensive: $4K for a PC vs $99 for C.
6. Ada Executables are Large & Slow.  4-6 times more so than C.
7. Ada is NOT FIPS-151 (Posix) Compliant.  NASA & NIST Document this in Depth.
8. Ada FY-91 R&D Funding was Zeroed.  ($100 Million was requested).
9. Ada's "Test Case" FAA Air-Traffic system is 5 years late & $7 Billion over
   budget.  IBM is prime contractor.
10.Congress imposed (1991) an Ada-Only Mandate, but added a "Where Cost
   Effective" clause, which negates the Mandate (See Below).

   Ada advocates have clearly overstated the cost saving Ada can deliver and
understated costs associated w/ its use.  Whether a Posix version will be
produced in the Commercial Market is doubtful.  Ada is currently being
bantered about as a "Born Again" Object-Oriented Language, which it is not.

   The inability to comply with Posix and the resounding success of C/C++
represent Ada's greatest threats.  DOD mandate to the contrary, Posix/GOSIP
standards have real teeth and firm Congressional backing.  Barred from its
"FediCare" market, out-done and out-gunned by C/C++, Ada is in Serious Danger
of following its namesake to an early grave:

+Ada.  Augusta Ada Gordon (1816-1851), Countess of Lovelace.  Daughter of
Lord Byron, club-footed Poet Laureate of England and all around scoundrel
whose amorous adventures in real life surpass those of the fictional Don
Juan. Reflecting the interests of Lord Byron's wife, the former Anabelle
Milbanke (a titled lady in her own right and the daughter of a high govern-
mental official comparable to our Attorney General), Ada displayed talent in
mathematics and ended up associated with Babbage during the period when he
used his Difference Engine to construct mathematical tables.  Ada is said to
have coded some of the algorithms used, thereby making her the world's first
computer programmer.  Jack Cooper of NAVMAT renamed DOD-1 (the new standard
language) "Ada" in her honor in 1979.  That may prove more appropriate than
originally intended.  There is a mystery surrounding the parentage of Ada and
the terms of Lord Byron's separation from his wife (they were never
divorced).  It is known that a furious scandal broke out about the time Ada
was born, a scandal serious enough to drive Lord Byron from England for the
rest of his life.  It is also known that he had a long term affair with his
half sister, Augusta Leigh, from which at least one child (Medora) was born
(July, 1813).  This was one of the factors (the death of his mother being
another) leading to his marriage to Lady Milbanke.  Given Ada's first name
(not a likely choice under the circumstances) and that the official records
were (and remain) sealed by the Crown, some authorities conclude that Ada was
the illegitimate offspring of long term incestuous inbreeding, a charge also
leveled at the language that bears her name.

>ADCCP.  Advanced Data Communications Control Procedure.  ANSI's HDLC. (See
HDLC & SDLC).

>ADP.  Automated Data Processing.  The old terms for IRM, Information
Resource Management.  The Realm of Computer Science.

>ADPE.  Automated Data Processing Equipment.

>ALGOL.  A variable star of the second magnitude in the constellation Perse-
us.  An 'Also Ran' language (ALGOL-60) specifically designed to optimize the
performance of its compiler via manually inserted cues.  The intent was to
improve language transportability by making its compiler easier (less expen-
sive) to write.  (See Also 'Systems, Evolution of').  Notable for the estab-
lishment of 'Structure Programming' constructs (IF-THEN-ELSE, CASE, etc.).
Taproot of Pascal, 'C' and Ada.  Product of a 1958 ACM effort better known in
Europe than here.  Never popular outside the university environment due to
the labor intensive nature of its complex syntax.

>AKA.  Also Known As.  An Alias.

>Algorithm.  Originally a mathematical formula or process.  Now a method to
accomplish some specific task.

>Algorithmic Pattern Generation.  The on-line real time generation of stimu-
lus/response test vectors in support of functional testing.  Widely used in
RAM testers.  Hindered by the need for very fast CPUs and simplistic pattern
algorithms.

>Alphageometric.  Any scheme of describing pictures using alphanumeric (text)
characters.  Implies a vector/picture element approach ala RMDraw rather than
a dot pattern approach ala PC-Paint.

>Alphanumeric.  Consisting of both text (A-Z) and numeric (0-9) characters.
Implies the ability to handle (as a minimum) the 64 character subset of
ASCII.

>ALU.  Arithmetic Logic Unit.  The computational section of a computer.

>A.M.  Amplitude Modulation.  An analog technique which impresses information
onto a carrier signal by varying its signal strength (amplitude).  Often
combined with PSK in modems.  See QAM.

>Analog.  Said of information.  The information content of a signal is con-
tained in the waveshape itself.  Since there is no basic predictability in an
analog signal, noise and distortion cannot be readily separated from the
original waveform.

>Analog Computer.  A collection of very high gain amplifiers, called "Opera-
tional Amplifiers" or "Op Amps" run under high degenerative (negative) feed-
back.  Excellent for modeling processes involving integration or differen-
tials, suffers from temperature drift and component shifts due to aging.
Generally considered obsolete.

+Analog Computer, History of.  Ignoring some early navigational aids (See
Also Stonehenge), the first analog computer was  "Napier's Bones".  So named
for John Napier(1550-1617), Laird of Merchiston, a Scottish mathematician who
discovered Natural (base 'e') logarithms.  His "Bones" were sticks of wood
marked off in logarithmic scales.  Calculations were made by arranging them
so that physical distances (representing the numeric values) were mechanical-
ly added or subtracted.  Mechanical calculators spun off an interesting
gender of electromechanical analog computers called "Difference Analyzers",
much used by Naval Fire Control systems throughout WWII (and still used by
the USS New Jersey in her main battery (16 inch) gun directors).  These
reached their peak of development in the late 1930's under Vannevar Bush
(1890-1974) who set down the principles by which all modern analog computers
operate. D.B.Parkinson and C.A.Lovell of Bell Labs developed the first suc-
cessful electronic analog computer and immediately applied it to the Mk 9
Anti-Aircraft gun director (1940).  Directly competitive with digital comput-
ers through the 1950's, analog computers were widely used to model mechanical
systems and to solve problems involving integral and differential calculus.
For a time, the advancements in solid state electronics more greatly benefit-
ed analog computers than digital computers, providing Operational Amplifiers
of such precision as to be called "Computing Amplifiers".  The increasing
power, decreasing cost and evolving techniques of numerical analysis associ-
ated with digital computers spelled the phase out of analog machines as
serious research tools by the middle 1960's (EK saw one of the last such
machines at U of Ia).  Analog computer techniques, however, continue to serve
diverse roles in instrumenta- tion, automation and control systems.

>ANSI.  American National Standards Institute.  The USA's Representative to
ISO.  IEEE, EIA, and NBS all recommend statards to ANSI.

>Anti-Aliasing.  A filtering process by which false responses are removed.
Aliasing arises when a signal is sampled below its Nyquist Rate.  Sometimes
this is done intentionally (as in Sampling Scopes).  Radio and TV a process
called "Super Hetrodyne" ( aliasing), but may experience "ghosts" (TV) or
"birdies" (Radio) from "Out-of-Band" signals.

   Failure to recongnize a spurious response (they often appear quite genuine)
can be embarrassing.  Consider how the FBI must have felt when they discovered
that the "Lady in Red" had fingered the wrong man.  Supposedly shot dead,
Dillenger sent Christmas greetings from Argentina for decades thereafter.
            (Source: A Great-Grandniece working here).

>APL.  A Programming Language. Title of a book by Dr. Kenneth Inverson
(Wiley,1962) describing a form of mathematical shorthand useful for solving
problems involving arrays, vectors and field theory.  An IBM computer lan-
guage (1965).  Very Powerful.  Highly obtuse.  Virtually unreadable. Requires
a special character set.  Reads right to left (backwards).  Has a small (but
avid) body of users.

>Archive.  A file which is made up of the contents of other files. Usually
some utility program such as Unix's "ar" tool is used to create and maintain
archives which, generally, are data compressed for more compact storage.

>ARQ.  Automatic Retransmission Request.  Specifically, the code word in a
link protocol scheme requesting retransmission of a busted data block (origi-
nated by BiSync).  Generically, any scheme to correct bit errors in a serial
data stream by segmenting traffic into "Data Blocks" protected by a BCC
which, if found in error, triggers an automatic discard/retransmit cycle.
Used by BiSync, SNA, DECNET, packet switched nets and some LANs.  As BER
climbs, effective channel throughput falls, becoming effectively zero at
about 1/100 BER (about the noise level of a Dialup Telephone line).  See Also
Forward Error Correction.

>Array Processor.  A small peripheral computer specifically designed to do
matrix math and/or DSP algorithms (e.g. FFT) very rapidly.

>Artifact.  An image, voltage, reading, etc. left over from a previous test
run.  Unless cleared away, these can cause puzzling failures which really
aren't.

>Aspect Ratio.  The ratio of the height to width for an object, character or
plotting universe.  When the aspect ratio of the universe in which a figure
is plotted differs significantly from that of the universe in which it was
created, circles become flattened, labels drift out of alignment and the
whole image seems to be "stretched" out of shape.

>Assembly Language.  The native binary code for the computer under discussion
converted one-to-one to (usually) 3 letter representations called
"mnemonics". Typically 10 times harder to write than a high level language
like Fortran. Virtually unmaintainable.  Difficult to Debug.  Fast.   Re-
quires tools such as assemblers, linkers, monitors and debugging aids.
Minimal use advised.

>Asynchronous.  Said of data communications processes.  Also called "Start/
Stop".  A scheme to control the build up of timing error by resynchronizing
the distant end each character cycle using character framing bits called
"Start" and "Stop" bits.  Originally a teletype technique, it is still used
widely.

>ASCII.  American Standard Code for Information Interchange.  An 8 bit code
in which 7 bits are defined.  By tradition, the 8th bit is used for parity
checking during telecommunications.  Seven level ASCII has 128 characters, 96
of which are printable.  Six level ASCII has only upper case characters, 64
of which are printable.  Four level ACSII is 8-4-2-1 BCD.  ANSI Standard
X3.4-1977 (Revised 1983). Also ISO-STD-646 and CCITT Alphabet No. 5.

>ARPANET.  Advanced Research Projects Agency Network.  Operational 1969. The
first successful packet switch network. Now old and difficult to
expand/maintain. Split c1985 into MILNET (Also called DDN) for DOD and ARPA-
NET for everyone else.  Based on TCP/IP.  MILNET is accessible thru a gateway
in DP via Sytek.

>ASIC.  Application Specific Integrated Circuit.  The "Now" name for "Semi-
Custom" ICs.  ASICs are designed much like PCBs in the jelly-bean chip era,
i.e., the "DIPs" are now "Standard Cells" and the printed wiring is now the
metallization.  Avoiding pinouts increases speed, improves reliability and
simplifies designs.  On the down side, ASICs are a repairman's nightmare
since, by definition, they are non-standard (and probably unavailable down-
stream).

>ATE.  Automatic Test Equipment.  A machine used to test electronic parts/
assemblies.  Consists of: A Test Head (to mount "Fixtures"), a pool of re-
sources (stimulus/response instrumentation, power sources, etc), a switch
matrix and a controller.  (Absence of the switch matrix implies a single
purpose "Test Set"; ATE implies general purpose applications).  System re-
sources are generally shared and usually are not stand-alone boxes (the
"Rack-and-Stack" ATE being an exception), although discrete instruments may
be incorporated (as VS-5 on the 3270 ATE incorporates an HP-2961 DPS).  ATE
implies a system level integration that normally includes a "Test Language".
ATE may be small ("Bench-Top"), but usually is big, frequently weighing
several tons (3 for the L260) and costing multiple Millions of dollars.

+ATE Programs.  ATE represents one extreme of the software envelope.  Classi-
cal Data Processing (DP) and Real-Time Environments (RTE) form the other two.
In DP applications, the focus is inward toward the CPU w/ data structure
being the predominant program design factor.  DP programs should be highly
modular w/ very simple control structures.  RTE encompasses data communica-
tions and other like situations in which the focus is outward from the CPU.
Programs and control structures are very simple to insure adequate speed in
servicing "interrupts". An RTE system does not have a "program flow"; it has
a game plan for responding to "tickles" from the outside world.  ATE is so
unlike both of these that a strong argument can be made that an ATE program
is not computer software at all.  In ATE, data structures are trivial, pro-
gram flow is linear and control structures are complex.  The CPU exists as a
"window" through which the programmer fiddles with the instrumentation there-
by performing the intended tests.  ATE programming is the programming of
testing resources, not computers. Under "Store-and-Test" operation (the most
common approach), the test situation is set up and the computer is placed in
a WAIT state until the measurements have been taken.  The computer is too
slow to participate; it is a witness, nothing more.

>ATLAS.  Abbreviated Test Language for Avionic Systems.  A DOD "Standard" ATE
language hyped as THE answer to ATE program portability.  Actual ATE program
transportability involves these seven factors:

   1. Hardware Capabilities     --> Can't Use What's Not There.
   2. Machine Configuration     --> Wiring Must Match.
   3. Fixturing                 --> Must Get to DUT.
   4. Operator Interface        --> Instructions/Options/Intended Use.
   5. Data Collection/Presentation/Formatting/Storage.
   6. Operating System          --> Type/Version.
   7. Language                  --> Syntax/Structure/Flow.

  ATLAS addresses only Language.  Successful within the framework of NAVAIR's
VAST (Versatile Avionics Shop Tester), which controls the remaining six
factors, ATLAS became IEEE-461-1976 by changing 'Avionics' to 'All' in the
acronym.  Card Image oriented.  Strong in constructs which set up instrumen-
tation prior to test execution, but weak in hardware specific constructs
necessary to perform the actual test.  Compiled.  Lacks interactive and User
Friendly constructs and is severely limited in the data analysis area.

---> Update 89: A new version, C/ATLAS is IEEE-716-89.  It adds the statement
constructs of the "C" language but none of the compactness, power or flexi-
bility while retaining the user hostile unnatural card-image syntax of previ-
ous ATLAS implementations.  Avoid.

>AUTODIN.  A worldwide secure message switch system designed and operated by
Western Union, leased to DOD.  Now outdated.

>Automatic Program Generator.  A class of programs that write made to order
programs.  Good results have been obtained in limited range applications,
e.g., report writers for DBMS systems.  Locally, S.E.T.U.P. generates up to
80% of the text for 3270 ATE test programs (done primarily to enforce a
standardized format).  Despite claims to the contrary, machine written pro-
grams always have more overhead, take longer to execute and are frequently
less easily maintained than regular (custom) software.  Still, a semiskilled
user may well obtain acceptable results quickly with little effort from an
APG package.

>AUTOVON.  A worldwide voice network operated by DOD to support its opera-
tions.

>awk.  A Unix Filter that is a line/field oriented pattern match/action
language resembling pseudo-code.  Awk programs are very short, usually a few
lines, and frequently perform almost magical text transformations.  Created
in 1977 by Alfred Aho, Peter Weinberger and  Brian Kernighan (co-authored of
"C") and significantly expanded as nwak ("new awk") in 1985.  While AT&T
maintains otherwise, insiders report awk originated with Kernighan's frustra-
tions in updating his telephone listings file using "C", hence the "Quick-N-
Dirty" syntax and powerful search/action language which blends the "regular
expressions" of the Shell into "C" itself.  Absolutely magic.  Highly Recom-
mended.

                                    -B-

+Babbage, Charles.  (1792-1872)  Inventor of the locomotive "Cowcatcher" and
one of several mathematicians instrumental in bringing about the adoption of
the 'd' notation in Calculus.  A professor of mathematics at Cambridge.
Designer of a successful hand operated integer computer he called a "Differ-
ence Engine" (1822), which he used to calculate a number of math tables used
widely. Over the years, he planned an enhanced version of his machine and
spent some 23,000 pounds (6,000 of which was his own money) attempting to
build it. By the time he abandoned that project in favor of his ultimate
dream machine, the "Analytical Engine" (1833), he had exhausted both his
governmental and personal resources.  To finance this new venture, he used
the Difference Engine in a scheme to handicap horse races, a matter that went
well enough at the start and then went broke in a flurry of increasingly
desperate bets.  The Analytical Engine, a binary computer capable to doing
decimal math, was never built. Later analysis of his design disclosed it to
be surprisingly advanced, featuring about 15Kb of mechanical RAM, punched
card input and stored control programs with the ability to alter execution
based on computed results. Perhaps too intricate to have been fabricated
given the technology of the time, the Analytical Engine, Babbage himself and
binary computers in general fell under a cloud as a result of his racing
venture that lasted over a hundred years.  Revived by Howard Aiken of Harvard
who approached IBM in 1936, the Analytical Engine got a million dollar new
lease on life.  The war, however, demanded immediate results and the actual
machine, the Mark I was much changed having dropped many of Babbage's innova-
tive concepts.  The "Advanced Difference Engine" was successfully fabricated
by a Swede (for which he was Knighted) and demonstrated at the Paris World's
Fair (for which the Effel Tower was built).  Sold to an observatory in New
York state, it served many years before ending up on display at the Smithso-
nian.

>Backup.  The process of making a copy of all or part of the file system in
order to preserve it should a system crash occur (usually due to a power
failure, hardware error, etc.).  This is a highly recommended practice.

>Balanced line.  A data transmission method in which both wires of a twist
pair are driven (out of phase).  Provides significant advantages over Common
Mode Noise, which is induced equally on both wires.

>Bank Switching.  A method of extending the addressing range of a CPU to
cover larger memory areas.  Based on a "base address register", bank switch-
ing breaks RAM into "Pages" of RAM (often in 64K chunks).

>Bar Code.  A scheme for representing alphanumeric data in the form of thick
and thin bars.  Popular formats including "3 of 9" and UPCs used on grocer-
ies. Read with either a handheld photo-optical wand or a fixed "scanner".

>BaseBand.  Said of LANs.  A digital technique in which the data is sent as
DC pulses on a transmission line.  The sharp edges of the digital signals
result in sidebands splashed over a wide spectrum.  Used on twisted pair or
coax.  Sometimes on fiber optic cables.  Example:  Ethernet.

>BASIC.  Beginner's All-Purpose Symbolic Instruction Code.  Introduced in
1962 as a means of teaching FORTRAN.  Quickly overran FORTRAN as the widest
used language.  First officially recognized as ANSI Minimal BASIC developed
at Dartmouth College in 1974.  Never popular, Dartmouth BASIC did much to
further the feeling that BASIC is a toy.  MicroSoft BASIC appeared first on
the TRS-80 Level II computer and later on CP/M to become a defacto standard.
A fully featured BASIC, MicroSoft put BASIC back into the serious language
category. Hewlett-Packard's "Rocky Mountain" BASIC extended the reach of the
language by theft from APL, PL/1, ALGOL, Pascal and Fortran.  Extended
slightly, this is the ANSI BASIC-89 standard. Usually interpretive, sometimes
compiled. Line oriented.  Easy to learn and use.  Very powerful.

---> Update 90:  Released 1 Jan 90, PowerBasic 2.0 represents the first of
the ANSI/ISO compliant PC Basics.  Gone are the Line Numbers and need for
GOTOs that marred previous versions.  It looks like Pascal without the silly
semicolons, reads like Basic and runs like wildfire.  The IDE (Integrated
Development Environment) resembles Turbo-C.  The compiler rips 30,000+ lines/
minute and the code is nearly as compact as C and nearly as fast
(particularly doing Strings).

   There is a trend in ATE machines away from Pascal (which proved overly
modular) back to Basic.  You can do more, faster in Basic than any other
language.  The ultimate combination, Basic w/ calls to C, isn't here yet.
Stay Tuned.

>Batch.  An antique style of computer operation in which jobs are submitted
(often on punch cards), run and returned w/o user interaction ala a laundry
service.  Worthless in this form, Batch survives as an option on some time-
share systems (normally a lower cost option) whereby the user queues his job
to run at a lower priority w/o interaction.  The user may then sign off and
pick up the results later.  Often used for simulation tasks once the obvious
errors have been smoked out of the model as such computational intensive
tasks have long run times and produce little output of note until near the
very end.

>Batch Stream.  A file containing pseudo-keyboard entries.  When activated
the file carries out some useful task.  Used by DEC, Univac, and others.
Called ".BAT" files on IBM-PC clones.

>Baud.  The signaling rate on a communications path.   Unless some bit com-
pression technique like Quadrature Shift PSK is used, the baud rate and
bits/second rate are equal.  Named after the inventor of TTY, Baudot.

>Baudot.  A 5 bit TTY code once widely used by DOD.  Baudot machines are
easily identified by the presence of keys marked [LETTERS] and [FIGURES] and
the absence of conventional typewriter shift keys (Baudot code does not
support Lower case text) on the keyboard.

+Baudot, Jean.  (         ) Officer of the French Telegraph Service and
inventor of the first practical printing telegraph machine (Teletype) and the
code by which it ran (which was named in his honor).  Demonstrated in 1875
and officially adopted in 1877, Baudot TTY is the basis of the worldwide
TELEX network.

>BCC.  Block Check Character.  A character or group of characters added as a
tag to a recorded or transmitted block of text to detect bit errors.  May be
a tally of the binary values of the bytes (usually modulo 2^16) [a 'Check
Sum'], an LRC or a CRC tag.  Check sums are used on the HP-9845 system. SRM
and X.25 use a CRC scheme.  Nine track tape uses an LRC scheme.

>BCD.  Binary Coded Decimal.  A 4 bit representation of the numbers 0-9.
Several forms exist, although 8-4-2-1 BCD predominates as it is a subset of
ASCII (4 level ASCII).

>Beam Penetration.  A method of producing multiple colors from a conventional
CRT by double coating the faceplate w/ phosphors of different colors.  Low
energy beams excite only the inner layer.  High energy beams excite both by
"penetrating" through the inner layer.  By varying the energy of the writing
beam, several distinct colors can be obtained.  Never really popular, this
type of CRT is sometimes found on oscilloscopes or monitors used on test
gear.

>Bed-of-Nails Tester.  One of four types of common ATE (the others being:
Bare Board, Edge Card and Chip testers) characterized by a physically large
test head fitted w/ vacuum pull-downs and many Pogo-Pin "Nails" that probe
the underside of a populated circuit board to allow "In-Cicuit" testing. BON
testers use hefty drivers of modest speed to "Overdrive" circuit nodes on the
DUT thereby performing the tests.  Contrast this high current, high capaci-
tance, low speed environment to the high speed backplane emulation of the
Edge Card tester or the super low capacitance, high speed, low noise circuit
board emulation of the Chip tester.

>Benchmarks.  Originally, targets from a rifle fired on a "bench rest" (a set
of clamps).  In modern computerese, the process of testing different machines
and software products against common, meaningful standards.  As in all forms
of testing, this is more "art" than science.  There is much disagreement
about what constitutes a valid performance test.  The "Whetstone" (See Same)
tests have fallen into disrespect since the basic premise that everyone would
be running Pascal has proven false.  Now there are "Dhrystones" and many
others.  As RISC machines spread in use, performance measures other than MIPS
or FLOPS (See Both) are sorely needed, hence the effort currently being
expended.

>BER.  Bit Error Rate.  Number of bit errors/Number of bits sent.
>Bernoulli Box.  A flexible disk drive having the form factor and handling
characteristics of a (hard cartridge) flexible disk, but the operating char-
acteristics of a Winchester.  Spun at hard disk rates (3,600 rpm), the flexi-
ble media is stabilized by a "Bernoulli Plate", a flat surface having a vent
near the hub.  As air accelerates radially outward, a low pressure area forms
creating an air bearing.  The head is mounted in a simple slot without need
of gimbals or springs.  The disk "dimples" around the head, which protrudes
slightly below the plate.  Any disturbance of this aerodynamic balance causes
the flexible media to fall away from the head resulting in (at most) a "soft"
(recoverable) error.  A very good idea, Bernoulli Boxes suffer from poor
marketing, no standardization and greedy vendors who insist on pricing them
like removable Winchesters.  Recommended.

>Bias.  A Preloaded parametric offset.  In Class A amplifiers, the voltage or
current used to establish the quiescent point.  In analog tape recorders, a
high frequency signal used to "chop" the audio to avoid magnetic saturation
(hence the need for a different setting for "Chromium Oxide" tapes).  In
Statistics, the tendency of sample data to converge on a value different from
the natural average of the population at large.

>BIOS.  Basic Input/Output System.  In CP/M. the section containing the
hardware specific (device drivers) part of the operating system.  This is the
portion that must be "patched" (customized) when CP/M is installed or when a
new peripheral is added.  IBM introduced the PC with a ROM BIOS that, until
1983, stumped imitators.  Phoenix Technology reverse engineered the ROM,
wrote a detailed functional spec. and employed a "clean team" (who had never
seen an IBM PC before) to independently write a functional equivalent. Well
done (IBM declined to sue), Phoenix ROMs power all PC clones.

>bis.  A terms appended to by Standards Committees to indicate a second
(usually preexisting) option.  For example, CCITT calls RS-232 "V.22bis". You
may also encounter a "ter" (3rd option) suffix.

>BiStable Storage Tube.  A 1968 technology popularized by Tektronix in the
4010 family of CRT terminals.  Information is stored on the face of the tube
by backing the phosphor with a photosensitive semiconductor.  Writing is done
using a high power electron beam that punches through to light the phosphor.
A swarm of low power electrons from a pair of flood guns maintains the image
by passing through the "switched ON" photoconductor directly behind written
areas. Graphics without large system overhead is a major advantage of this
technique. However, the whole screen must be erased and rewritten to change
anything, a factor that has caused this technology to phase out in favor of
the familiar TV type of raster scanned display.  A type of Direct View Stor-
age Tubes (DVST). See Also Storage Tube.

>BiSync.  What everyone else calls what IBM calls BSC, Binary Synchronous
Communications.  A 1969 IBM standard widely used.  A byte-oriented protocol.
Basically half duplex.  Uses Ack/Nack flags.  A "line block" is 80 characters
which is also the size of an IBM card.  Performs badly on long links. Satel-
lite shots have killed BiSync for long haul work.

>Bit.  BInary digiT.  A number w/ 2 values (0/1).  The smallest part of a
Byte or computer Word.  Bits are usually Binary Weighted (assigned powers of
Two).

>Bit Bucket.  A place to send unwanted bits/bytes/text.  Frequently called
"null" or "/dev/null" ("NUL:" on DOS).  A WOM.

>BITE.  Built-In Test Equipment.

>Bit-Mapped Graphics.  A method of creating images made up of dots (pixels),
each of which has a unique location in RAM assigned to it.

>Bit-Oriented Protocol.  A data link control game plan for serial bit
streams.  Six "1's" represents a flag pattern.  The sender pads with a "0"
whenever 5 "1's" occur in the data itself to avoid an accidental flag.

>Black Box.  A generic dummy functional block.  May be Hardware or Software.

>Block.  A badly abused term.  As originally intended, a Block is the small-
est amount of data that can be read from or written to a mass storage device.
The smallest "real" Block is on physical "record" (usually a disk sector).
As Buffers got bigger, it became common to read/write several records at a
crack ("Track Buffering" and the like), a "Block" being the size of the
buffers used.  To complicate matters, IBM, DEC and Unix frequently speak in
terms of "Standard Blocks" (512 bytes under Unix) even when the actual
read/write "chunk" is two or four times larger.  See Also Cluster.

>BOOT.  Bootstrap. The process of loading the operating system into a soft-
loaded computer.  Also used to begin fresh after a system crash.

>bpi.  Bits per inch.  Information density indicator for magnetic media.

>Break.  Originally, the physical opening of the electrical circuit (which
caused the distant TTY machine to "Run Open" generating enough noise to alert
the operator).  Now considered to be the sending of a continuous "Space" (the
"start" pulse in asynchronous transmissions) for approximately 200 msec
to gain the attention of the distant end.

>Bridge.  A black box found in LANs.  May link together sections of baseband
LANs (which usually don't branch well).  In broadband LANs, serves to link
modems operating on different bands.

>BroadBand.  Said of LANS.  An analog technique in which RF modems are used
to send digital signals on a broadband media, usually coax.  More complex
than baseband, but benefits from cable TV technology.  Example: Sytek System
20.

>BSD.  Berkley Software Distribution.  The current (1988) other "flavor" of
Unix (See Also SVID) known for its "C-Shell" and elegant Mail system (now a
part of System V as "mailx").  Strongly DEC VAX oriented, BSD 4.3 is the last
VAX release.  Apparently DEC and Berkley had a falling out over 4.3's memory
manager SNAFU that significantly slowed system performance.  Whatever
happened, the "fire went out" at Berkley, leaving OSF to carry the BSD torch.

>Bubble Memory.  A 1977 digital storage technology based on circulating
magnetic domains in a thin film magnetic media.  Viewed under polarized
light, these magnetic domains resemble bubbles in a moving fluid, hence the
name. Never Popular.  Non-volatile.

>Bubble Sort.  The simplest (and least efficient) of several Minimum Memory
sorting algorithms (the best being the Shell Sort).  Much greater speed is
possible using the "Heap Sort" or "Quick Sort" algorithms.  Both require more
RAM, coding complexity and startup overhead than Minimum Memory sorts.  For
general use, the Shell Sort is Recommended.

>Bug.  A mistake.  Specifically, a mistake in software, the removal of which
is called "DeBugging".  Historically, the term predates software by several
centuries, being in common usage in the time of Shakespeare (a letter refer-
ring to "bugs" in a manuscript survives).

  The association w/ computers originated w/ Adm Grace Hopper (USN, ret.),
the Navy's grand old Lady of software (she wrote COBOL). While working on the
Harvard Mark I computing engine during WWII, a program malfunction was labo-
riously isolated to a stuck signal relay (used for RAM)  which had jammed on
a crushed moth.  Carefully removed, this "bug" was taped into the operations
log w/ the notation "Found bug in program, removed same."  (This original
"Program Bug" is on display at the Naval Museum, NWL Dahlgren).

>Buffer.  A holding tank for data.  Often used to handle speed differences.

>Buzz Word.  A bit of technical jargon (or pseudo-jargon) used to "Jazz Up" a
conversation, presentation, etc. to appear "High Tech".  Actually a form of
Noise, "Buzz Words" obscure what is being said (which is often the intent).
Avoid.  Also, Avoid those who Use.

>Byte.  Originally, the amount of data that could be fetched from memory in a
single read cycle.  Now considered to be 8 bits by common usage.


                                    -C-

>C.  Formally introduced in 1978, 'C' was written by Dennis Richie of Bell
Labs as a rewrite of Brian Kernighan's 'B' Language, a condensation of BCPL
(Basic Combined Programming Language), itself a cutdown of CPL (Combined
Programming Language), an abbreviated extract of ALGOL-60.  Terse.  'C'
assumes the user to be a competent professional and provides tools (and the
ability to create tools) of sweeping scope w/ few restrictions and fewer
safe-guards.  For example, the use of pointers (a potent and sometimes deadly
technique) is encouraged.  Specifically designed for systems work (the trans-
port of Unix being its first task), 'C' functions as a 'Portable Assembly
Language' providing bit manipulation and arithmetic constructs not usually
found outside mnemonic assemblers.  Not really a high level language compara-
ble to Fortran, 'C' can serve reasonably well as a 'Moderate Level' language
if supported by a Library of hardware specific routines.  'C' compilers are
small, fast and relatively easily written.  ('C' has only about 30 Keywords
in the entire language).  'C' object code is generally compact and comparable
to hand generated assembly.  AKA ANSI C-89.

>C++.  An Object-Oriented Language by Bjarne Stroustrop (1987) usually imple-
mented as a PreProcessor to ordinary C.  Apparently this was the intent of
the Author as the double-plus notation in C means "Post Incremented."  See
Also OOL.

>Cache.  A French word meaning "To Hide".  A virtual memory technique used to
trick the CPU into believing that all its RAM is very fast.  Less elaborate
than disk based Virtual Memory methods (which may be employed simultaneously
as well).  Depending on the programs run, may produce dramatic speed gains.
Found in high performance systems.

>CAD.  Computer-Aided Design.  Specifically, the partial automation of the
draftsman's art.  Now includes (more or less) most of a draftsman's task area
including bill of materials, layout, stress analysis, etc..  Originally
mechanical, now extended into various phases of electronic design including
PC board layout and chip design.

>CAE.  Computer-Aided Engineering.  Everything an engineer or technician does
with a computer.

>CAI.  Computer Aided Instruction.  The use of computers in a teaching envi-
ronment as teaching aides, programmed learning engines and as teacher
substitutes, particularly in mathematical or language instruction and in
situations involving repetitive tasks.

>Calculator.  Strictly speaking, a machine that performs computations serial-
ly, each computation cycle being specifically initiated by a human operator.
This distinction is very poorly delimited as highly interactive computers
resemble calculators and very smart calculators (such as pocket sliderules)
resemble computers.

+Calculators, History of.  The abacus is basically a scratch RAM for a human
doing mental mathematics as it has no computational power itself.  The slide-
rule is a logarithmic engine using numeric values converted into scaler
distances which are mechanically added or subtracted.  The first mechanical
adding machine was designed by Pascal (1642).  Gottfried von Leibniz (1646-
1716) improved the design into a "Four Banger" which he fabricated in 1694.

  Babbage's Difference Engine was his only successful design.  Despite spend-
ing some $75K in the process, his improved model never got off the drawing
board.  Dropping that, he began work in 1833 on his dream machine, the Ana-
lytical Engine, considered the most intricate calculator ever designed.  The
familiar keyboard style adding machine was patented by Felts in 1885 and
immediately improved by William Burroughs (1855-1898) into the first commer-
cially successful calculator.  Burroughs went on to expand this into book-
keeping machines for business users.

  Tabulating machines based on the punch card were invented by Hollorith in
1889, just in time for the 1890 census.  This technology founded IBM in 1911.
Although mechanical calculators improved greatly with the addition of elec-
tric power, the technology peaked in the middle 30's in Naval Gun Fire Con-
trol  systems such as those on the Iowa Class Battleships.

  The last major calculator development was the IBM sponsored Harvard Mark I
Computing Engine (completed in 1944).  After that IBM's attention turned to
electronic calculators such as the model 602 and 603 introduced in 1946.
IBM's last large scale calculator (technically it was a computer) was the
model 650 Selective Sequence Electronic Calculator, which used a rotating
drum memory to "punch its own buttons".  This machine was widely used for
scientific work throughout the 1950's.

  The last specific calculator of major importance was the HP-35, which
banished the sliderule and sparked the microcomputer revolution.

---> A Footnote: Smithsonian Researchers, starting from an off-hand reference
in a letter to Ben Franklin, tracked down proof positive that Pascal was at
least a Century Late in Inventing the Mechanical Calculator.  From a descrip-
tion in Vatican Archives, a Working Model of a Polish "Four-Banger"  was
uilt in 1957.  The Inventor perished in the Black Plague that swept Europe
in the 15th Century, Cheating Him of Just Recognition.  (It Figures).

>CALS.  Computer-Aided Logistics Support.  Another massive DBMS from the fine
folks who brought you TISS (Tester Independent Software System), ATLAS and
ADA.  CALS is a CS's idea of how technical information should be handled.
Like TISS, CALS is not likely to be practical in our lifetimes, but good
things will fall out from the effort, among them is EDI.

>CAM.  Computer-Aided Manufacturing.  A catch-all term that encompasses
elements of CAD/CAE and numerically controlled (NC) machines plus the inven-
tory/cost accounting and scheduling aspects of manufacturing.

>Capstan.  The component of most tape recorders that acts (with the aid of a
pinch wheel) to pull the tape over the record head at a constant speed and
tension.  Because capstan drives are unidirectional and constant speed,
digital tape drives must "declutch" the capstan (usually be releasing the
pinch wheel) during fast forward, rewind and search cycles.  One major advan-
tage of the 3M cartridge design is that no capstan is required.

>CASE.  Computer-Aided Software Engineering.  Whatever that is.

>Cast.  The process of converting a data from one TYPE to another.  Some
Languages (such as BASIC) do it transparently.  Others, such as "C" do so
during Assignments (A = B causes the data in B to become the data TYPE of A),
but perform "Type Checking" elsewhere.  ADA prohibits automatic Casting,
which makes it labor intensive and Programmer Hostile.

>CCITT.  Consultative Committee for International Telephone and Telegraph. A
standards body dealing primarily with telephone and data communications.
They originate the 'X.' and 'V.' standards such as 'X.25'.

>CD-ROM.  The same optical "Compact Disk" media as the musical versions
(including the same players) except that the binary information "burned" in
is digital data instead of digitized audio.  An "Album" sized CD-ROM holds
550 Mb (equal to a stack of 360K Floppies over 12 ft high) and currently
(1989) costs less than $2.00 (qty of 100).

>Centronix.  A defacto standard parallel protocol for printers using TTL
Levels, strobes and flags.  Pin 1 is Data Strobe, a negative edge occurring
50 uS after data appears on Pins 2-9 (D0-D7 POS True) and lasting at least
1.2 uS.  The printer signals acceptance w/ a 100 nS pulse.  Data Valid ends
10 uS later.  This gives a nominal throughput of about 10 Kb/sec.  Pin 11 is
the BUSY line and is sometimes used for level shift handshaking.  Pins
12/13/31/32 are flags.  Pins 19-30 are data grounds.  The remaining pins are
(Officially) Unused, but may provide Power (+5 V) or other signaling. Al-
though Centronix officially uses a 36 Pin "Blue Ribbon" connector, it is not
unusual to find Centronix ports implemented on PCs as DB-25 connectors, the
type also used for RS-232 Serial Ports.  An idle Centronix port has a TTL
High (+5 V) on Pin 1.  An idle RS-232 port has a NEG voltage on either Pin 2
or Pin 3.  See RS-232-C.

>Character-Oriented Protocols.  Data Link game plans using "Reserved  Charac-
ters" to pass control signals back and forth.  Examples: BiSync, DECNET and
Kermit.

>Chip.  A semiconductor device.  So named for the fragments broken from  the
fabrication die ("Wafer") prior to final assembly.  See Semiconductor.

>Circular Buffer.  A buffer which automatically "wraps around" so that it
performs as a circular queue.  The fill pointer always advances, the empty
pointer chases to catch up.  Found in Terminal Emulators.

>Cluster.  The smallest amount of data that can be read/written to a DOS disk
(2048 bytes on Hard drives).  See "Block".  Also, a group of PCs or Worksta-
tions, usually networked around a File Server.

>CMOS.  Complementary Metal-Oxide Semiconductors.  A MOS microcircuit tech-
nology combining NMOS and PMOS devices on the same chip.  Like MOS, CMOS is a
low power, high impedance technology w/ very low (microwatt range) static
power draw and a resistive output characteristic.  More difficult to design
and fabricate, CMOS has traditionally been used for low power, low speed
applications.  During switching, CMOS is subject to an "overlap" during which
both FETs in the Totem Pole are conducting thereby drawing a pulse of power.
Careful matching of the N-Channel and P-Channel devices (a non-trivial task)
reduces overlap allowing faster operation.  So called "Dynamic" CMOS is about
three times faster than TTL w/ fabrication densities similar to NMOS.  CMOS
is subject to the same ESD hazards as MOS.  If input levels swing beyond the
power rails, the on-chip device isolation (always a problem) is subject to a
destructive breakdown called "Latchup".

--> Tektronix 3270 ATE User:  DO NOT punch the <STOP> button on the TSCU
while testing CMOS parts.  In their finite wisdom, Tektronix designers "Crow
Bar" the power supplies.  This assures that Vcc will drop faster than the
Pin- Electronics Drivers resulting in a "Smoke Test" via Latchup.  There is
nothing anyone can do to avoid blasting the DUT once the <STOP> button is
pressed.

>Coax.  Coaxial Cable.  A type of cable in which a central conductor is
suspended equidistant from a cylindrical shield sharing the same axis. A
quiet, wide band media used by many high frequency or high speed processes
including TV, radio, and some LANs.

>COBOL.  Common Business Oriented Language.  The one of the first high level
languages.  Developed by DOD (1956), but popularized by IBM.  Intended to
allow nonprogrammers (managers) to read and understand the programs.  A
dinosaur. Very difficult to write, upgrade or use.  Rather like a Model-T
Ford, refuses to die.  American business is estimated to have a 200 Billion
dollar investment in COBOL programs (1986).

>Codec.  Coder/Decoder.  The opposite of a modem.  Converts analog signals
into digital form for transmission.

>Command Interpreter.  See "Shell".

>COMMON.  A pool of variables held in a fenced off area that may be passed
from program to program as a block.  In general, COMMON variables do not
initialize and must be cleared before use.  Originated in Fortran, adopted by
BASIC.

>Compiler.  A program that reads a source code file of and writes an object
code file.  This operation is usually followed by a Linking process which
generates the executable program.  Compilers allow the use of Named Con-
stants, Macros and Header Files, all features that greatly simplify program-
ming and improve readability.  Recent advances in "Integrated Environments"
ala Turbo Pascal & Quick C have jumped Compilers back into the Mainstream.

>Composite Video.  A TV style signal containing blanking and sync pulses.

>Computer.  (1646)  A person adept at doing mathematics mentally (hence, the
"er" ending).  Now a digital machine having these four distinct features: A
processor (CPU). A memory.  An Arithmetic Logic Unit (ALU).  An input/output
(I/O) device or port.  Example: a pocket calculator.

>Computer Programming.  The art of causing a computer to do something useful.
Implies that unwanted behavior is avoided.  Consists of these distinct steps
(as a minimum):

  1. Defining the Problem to be Solved. --> What You Really Want.
  2. Outlining the Solution.            --> What is Acceptable.
  3. Selecting Methods (Algorithms).    --> How You Will Do It.
  4. Coding.                            --> Telling The Computer.
  5. DeBugging.                         --> Getting It Right.
  6. Testing.                           --> Proving It Works.
  7. Documentation.                     --> For You & The User.
  8. Maintenance.                       --> Upgrades & Fixes.

>Computer Science.  The profession dealing with the use of computers to
process large quantities of information composed of many jobs, each done
slowly, with the intent of maximizing the utilization of a shared, central-
ized resource. With its inward focus and basically batch orientation, CS
represents only one approach to computer use (other equally valid approaches
include ATE, Data Communications and Real Time Environments).  Within the
limited confines of its definition, CS approaches a true science in that
software situations are "knowable" and human error is the greatest source of
software reliability problems.  The only purely software profession with full
academic status, CS's aristocratic attitude (we are considered "Hackers") has
placed them outside the mainstream of computer evolution/innovation.

>Concatenate.  To splice together.  Said of Text Strings or Files.

>Concentrator.  Strictly speaking, any kind of mux.  By common use, a statis-
tical mux.

>Context Switching.  System overhead associated w/ the establishment, manage-
ment and collapsing of local environments in systems/languages allowing use
of local variables (BASIC-89, Pascal, Ada, Etc.).  A non-trivial matter.

>Contiguous.  Said of Disk Files in block sequential order start to finish.
Some systems such as Unix intentionally splatter files across the physical
disk.  Others, such as TEKTEST require executable (.TST) files to be block-
sequential to simplify loading.  Such systems may be recognized by the
presence of a "CUP" or "PACK" command which is used to gather together frag-
ments of unused space.

>Control Characters.  "Invisible" bytes intended to control a printer/CRT,
exercise Flow Control or control data links (See Character Oriented Proto-
cols).  ASCII provides 32 control codes as the first 32 defined bytes. Some
of these, like carriage return and line feed, are well known and universally
accepted.  Others, such as DC1/DC3 for XON/XOFF, have developed a standard
meaning by common usage.  One of ASCII's strengths has been the mechanism
provided for multicharacter control sequences via the "Escape" character,
these being called "Escape Codes".  Until recently, there was no standardiza-
tion of escape codes even among products from the same vendor. See X3.64.

>Co-Processor.  Originally, a slave CPU.  Now a processor specifically de-
signed for a single task, such as graphics controller.  Implies a secondary
role to the main CPU but business on a more coequal status than a slave CPU.

>Copy Protected.  A "Polish Pistol" which prevents the paying customer from
making backup copies of over-priced buggy software.  Hard disks have hung a
(well deserved) bad name on all copy guards. Never effective, Copy Protection
has launched many ventures including "Disk Doctor", "Lock Smith" and a news-
letter for Commodore 64 "Safecrackers", a hacker subculture complete w/
clubs, conventions and bulletin boards dedicated to the challenge of these
"electronic cross-word puzzles".

>Copyright.  A legal monopoly granted authors by Congress (generally for 75
years w/ option to renew) to encourage them to publish original works.  An
interesting twist is that a "Work of the United States Government" may not be
Copyrighted.  Section 105 of the Copyright Act of 1976 (17 U.S.C. 105) places
anything "prepared by an officer or employee of the United States Government
as part of that person's official duties" in the Public Domain.

>CORE.  SIGGRAPH CORE.  A graphics standard competing w/ GKS (See GKS).

>Core.  Originally, magnetic core memory, the main memory of a computer (made
up of tiny ferrite doughnuts ("cores") strung on a wire matrix).  Now gener-
ally used to refer to a computer's real memory (as opposed to Virtual Memory)
regardless of whether ferrite magnetic core RAM is actually used. True core
RAM is, in general, slow (725 nS cycle) due both to the current levels used
and the need to rewrite RAM locations after a read cycle (destructive read).
Magnetic core RAM does not "forget" when the power is removed
("NonVolatile").  Bulky. Expensive.

>Correlation.  The verification process by which two (ATE) environments are
matched within the limits of experimental (observation) error.  The method
used locally is called the "Gold Standard" method under which a known good
device is run on each machine, the results being compared factoring in the
precision of the instruments used.  Once so verified, test results can be
directly compared without "Fudge Factors".

>CP/M.  Control Program for MicroComputers.  The world's first PC-DOS.
This good idea and $500 founded Digital Research in 1975 (Corporate head
quarters was a remodeled tool shed in the back yard).  Six years later,
DRI grossed $26 million and signed up IBM, DEC, and Hewlett-Packard.  Now an
industry-wide defacto standard.  CP/M has been displaced by DOS and is cur-
rently (1989) of fading importance.

>CPS.  Characters Per Second.

>CPU.  Central Processing Unit.  The "engine" of a computer system.

>Crash.  The unexpected shutdown of a program or system.

>CRC.  Cyclic Redundancy Code (or Checking).  A scheme to detect the presence
of a bit error in a serial bit stream.  Based on the mathematical division of
binary polynomial, the CRC is the remainder after the division process.  This
value is tagged on at the end of a data block by the sender.  The receiver
can verify that no error has occurred by performing the same division process
and comparing the results w/ the tag.  If they match, there is a very high
probability (> 99%) that the data is good.  Popularized originally by hard
disk designers, CRC is a good idea that lends itself easily to a hardware
implementation using shift registers and feedback.  Used almost anywhere
blocks  of data are sent serially (BiSync, Tape Drives, Disk Drives, Packet
Networks. . and Kermit).

>Cross-Talk.  The "Spillover" of one channel's signal into another.

>Crowbar.  To rapidly discharge a power source through a low impedance to
ground thereby sharply ramping it and any attached decoupling capacitors to
zero volts in "zero" time.  So named for the practice of discharging B+
(plate) power supplies w/ a screw driver, metal rod or "Idiot Stick" prior to
maintenance or adjustment of electron tube circuits.  Once a design feature
in laboratory power sources, crowbar style current "latches" have been dis-
placed by "Fold-Over", a smooth transition from voltage control to current
limiting.

---> Tektronix ATE Users Note:  The HP-6129 DVS (VS5) uses a Crowbar Current
Latch which is potentially lethal to CMOS.  Also, the "Panic STOP" button on
the TSCU Crowbars all power supplies, a proven method to "Smoke Test" CMOS.

>CRT.  Cathode Ray Tube.  The "TV" screen used in many computers and termi-
nals.

>Crystal.  A piece of piezoelectric material (usually quartz) cut, polished
and mounted so that it can mechanically vibrate when excited by an electric
signal. Used as a "balance wheel" in digital watches.  Usually used to pro-
duce a  stable, accurate frequency (as in radios) or time period (computer
clocks),  crystals are sometimes used to build very narrow, high quality
filters for  instrument use.  Sometimes used as mechanical actuators as is
done in Drop On Demand Ink Jet printers.

>CSMA/CD.  Carrier Sensing Multiple Access w/ Collision Detection.  A method
of controlling access to a LAN for coequal stations.  Based on the old party
line gab session "Listen Before you Talk" protocol.  Most effective on short,
high speed links.  Superior to Token Passing in that it is self restarting in
case of a noise burst.  Access is statistically distributed, so time depend-
ent traffic such as digital voice is not supportable.  Claimed to overload
and "Block" under high traffic loads, real world systems have consistently
survived all overload attempts.  Apparently the processing overhead in the
nodes provides a safety margin such that 4 retrys is the longest wait time
ever actually observed.  Used by Ethernet and Sytek System 20.

---> Update 89: The debate over LAN protocols has cooled somewhat since
experience disclosed that statistical effects of buffering at the LAN nodes
(called "Queuing Theory") predominates over LAN access effects by 100:1. CSMA
works best when many nodes "chat" among themselves, each exchanging modest
amounts of traffic.  Tokens work best when a few nodes swap large blocks of
traffic.

  CSMA works best close in (echo-back intervals are short compared to packet
length).  Tokens work best where data blocks are long and handoffs are few.
CSMA is robust with respect to noise, Tokens are not.  CSMA LANs are peer-
equal and decentralized (usually an advantage).  Tokens allow levels of
traffic priority but require centralized administrative support.  CSMA's
chokes when everybody needs to talk at once, Tokens when everybody gets
"chatty" (Many short exchanges).  Both respond positively to algorithmic
"tweaks".  Neither is clearly superior to the other in general use.

  CSMA LANs are inherently heterogeneous (only the nodes actually exchanging
traffic need be fully compatible).  Token LANs are inherently homogeneous
(everybody plays or nobody plays).  Both respond well to standards such as
Ethernet and MAP (respectively).  Generally, a multi-vendor network is easier
to implement w/ CSMA.  Token LANs tend to "Plug & Play" right out of the box,
but risk obsolesce if standards change.

>Current Loop.  A method of data transmission over a metallic wire path in
which the presence of current flow is considered to be a "One" (Mark) and the
absence of current flow is a "Zero" (Space).  Originally 60 ma for TTY (130V),
modern versions are usually 20 ma (12V) or 6 ma (5V).  Revived by the
availability of modern photo-isolators, current loop is frequently used for
long wire runs in high noise areas.

>Cycle Stealing.  A method of interleaving a memory access task w/ normal CPU
operations using idle intervals when the CPU is decoding instructions and
making computations.  Also used to describe a similar scheme where clock
cycles are stolen by inserting Wait States into the CPU's operating cycle so
as to free up memory access cycles for some other task (such as DMA).

                                    -D-

>D/A.  Digital to Analog Converter.  The logical inverse of an A/D Converter.
A class of devices that convert numbers into voltage representations.  Basi-
cally the same precision/speed trade-off applies as w/ A/D converters.  Units
range from powerful/precise (but slow) Digital Voltage Sources (DVSs) to
video rate devices used in TV work.

>DAT.  Digital Audio Tape.  Compact Disk (CD/CD-ROM) technology done on
helically scanned 1/4 inch tape cartridges resembling 3-M "Mini-Cartridges".
Easily capable of holding 2 Gb, DATs (as currently marketed) contain a
"Feature" to prevent duplication of tapes/CDs, a bad idea.  So flawed, DATs
may be over-run by removable Read/Write optical disks.

>Data.  A collection of information.  Strictly speaking, "data" is the plural
form of "datum"  (a "Data Element), making the phrase "Data are processed"
correct.  However, the phrase "A collection of" is singular, making "data" as
commonly used singular: "Data was collected".  So data "is" processed in the
technical sense and "are" published in the strictest sense.  Such is Jargon.

>Data Acquisition System.  An ATE system w/o stimulus capability.

>Data Base.  A collection of information.  Implies storage in files on tape
or disk.  Small databases tend to be relational while modest to large ones
tend to be tree structured.  While they may be thought of as a large collec-
tion of index (3x5) cards, databases are most effective where maintenance is
via Transaction Processing and information extraction is via Report Writers.
If a key or pointer scheme can be used, databases can be much more efficient
than "barefoot" methods.  Databases tend to be like alligators, cute and
manageable when small, but they eat dogs and small children if allowed to
grow.

>Data Driven.  A machine or program controlled by the data it processes.
Specifically, a machine that can reconfigure itself on the fly to optimize
throughput.  The first such machine being the Navy's Enhanced Modular Signal
Processor (EMSP).

>Data Encryption.  Any method for encoding information in order to protect
sensitive or proprietary data.  There is no "perfect" scheme except one, the
"Write Once Pad", which is an "Off-Line" technique.  Given enough time and
resources, anything less can be "cracked."  On the other hand, Louis XIV's
"Great Cypher" held off determined professionals for more than a century,
long enough that the messages it protected were useless (except as historical
footnotes).

>Datagram.  A class of service on packet switched networks roughly equivalent
to a postcard (no reply required).  Used by many LANs including Ethernet.

>Data Link.  An end-to-end data path including the originator and the receiv-
er of the traffic.  Implies flow control.

>Data Set.  Telco jargon for a Modem.

>db.  Decibels.  A logarithmic scale reflective of the response of the human
ear to sound energy.  Usually referenced to 1mW @ 600 ohms (dbm) in telephone
work.  On this scale, -60 dbm is undetectable by virtually everyone.

>DBMS.  Data Base Management System.  A computer-aided card file.

>DCE.  Data Communications Equipment.  What the RS-232-C folks call a Modem.
Modems are supposed to use FEMALE plugs and send on pin 3.

>DeBugging.  The process of program purification.  AKA Software Testing.

>DeFacto Standard.  Something so Good or so Common that other similar
products are compared against it.  Functionally equivalent to a formal stand-
ard.  Set up by forces in the marketplace.  Examples: Selectric Keyboards,
MicroSoft BASIC, Centronix Interfaces, WordStar...

>Delimiter.  A separator in a data list (often a comma).

>Demand Paged.  Said of Virtual Memory systems.  Any of several methods under
which physical RAM is divided into sections ("Pages") and swapped to/from
disk in response to "Page Fault" interrupts generated by a "Memory Manager".
(See Virtual Memory, Operation of).  Demand Paging operates w/o regard to RAM
contents.  Other memory management methods work on a "JOB" basis swapping
entire tasks in/out (See Rollout) very much as Console operators did in the
early days.  A variation on the latter theme swaps in/out of "Virtual Ma-
chines" (a user's entire environment), an IBM technique.

>DES.  Data Encryption System.  An NBS standard algorithm for data encryp-
tion.  Suspected of being "cooked" so that NSA can easily "break" it. The NSA
insisted on a 56 bit key word which fits the algorithm poorly (it was de-
signed for a 128 bit key).  AKA ANSI X3.92-1981

>Dial-Back.  A simple, effective access control scheme based on the "Don't
Call Us, We'll Call You" principle.  A user initiates a session by calling a
"tickler" line, keying in a code number (usually with his touch tone phone)
and hanging up.  The computer crosses the code number to an authorized tele-
phone number and calls the user, who then logs on normally.  Very good, but
not perfect ("Call Forwarding" fools it).

>Digital.  Said of information.  The information is coded as the presence or
absence of some voltage, charge or the like at some specified location at
some specified time.  In the case of serial transmission, digital information
can be "regenerated" (reshaped and retimed) without affecting the information
content of the signal, a distinct advantage.

>Digital Filter.  A composite analog/digital/analog device emulating a purely
analog function (filtering).  One of the first widely used applications of
DSP (See Same), digital filters have been enthusiastically accepted by the
tele- communications industry for equalizers and line conditioners, applica-
tions where the additional hardware cost is offset by the advantages of long
erm stability and freedom from thermal drift (the "filter" is really an
algorithm which neither ages nor drifts).

>Digitizer.  The graphical inverse of a plotter.  A plotter takes numbers and
makes pictures.  A digitizer takes pictures and makes numbers.

>DIN.  Deutches Institute fur Normung.  The German equivalent of ANSI.

>DIP.  Dual In-line Package.  The common "Bug" form factor for IC's.

>Directory.  A file (or set of files) containing a table of contents for a
mass storage system (or portion thereof).  During media initialization, at
least one Directory file is established.  Systems such as TEKTEST and CP/M do
all their business in a single "Catalog-style" Directory.

  RSX, VMS, Unix and DOS call their catalog an "I-node" file, the exclusive
property of the Operating System.  Users interface w/ the I-node file via a
set of files ("Directories") which map I-nodes to User names.  Some systems
(notably Unix) allow I-nodes to be "linked" to several different User names,
each equally valid.

  Only the first access of a file is by name.  Once the System has traversed
the "Path" through chained subdirectories, it has the "I-node" number.  From
that point on, the System works with the I-node file, treating it as an old-
fashioned "Flat" catalog.

>Disk Cache.  A variation of Track Buffering under which a several Blocks are
read into RAM w/ the hope that future READs will "Hit" on data in the Buffer.
Depending on the Application, dramatic speed increases (up to 10x) are com-
mon.  When WRITEs are involved, Cache can be risky as the File may be cor-
rupted if power is lost before the Buffer is written to Physical Disk.  If
the Hardware  does not support a Power-Fail Routine (and PCs don't), it is
standard  practice to "Write Thru Cache", i.e., to update the Buffer and
immediately  write it to Physical Disk.  This trades WRITE speed for better
Reliability.

>Disk Pac.  A removable hard (flying head) disk with its protective enclo-
sure. A single disk (platter) assembly is usually called a "cartridge".
Implies a stack of platters in one assembly.

>Distortion.  The corruption of a signal by noise and degradation so that the
waveshape is altered.  In digital signals, measured in "%".  35% is generally
considered a practical maximum.  May be removed by "regeneration" which
reshapes and retimes the signal.

>DMA.  Direct Memory Access.  A high speed transfer technique in which the
CPU hands control over to a DMA controller and then goes to sleep.  The DMA
controller performs the transfer at the highest possible rate and then wakes
up the CPU.

>Document Processing.  The creation, editing, printing and storage of inte-
grated text/graphics documents as a single, logical unit.

>Dongle.  A software locking device plugged into an RS-232 port on a PC
which, when tickled, reports out a magic number, phrase, etc. that identifies
the user as being authorized to operate the installed product.  Better than
the old "Master Floppy", but still a bad idea.  Avoid.

>DOS.  By common usage, MS-DOS for Intel 80x86 processors ala IBM PC/XT/AT.

>Dot Matrix.  Literally a rectangular group of dots.  Usually applied to a
printing/display technique in which the dots are treated as pixels from which
characters (usually text) are constructed.  Popular formats:  5x7,7x9,9x12.

>DRAM.  Dynamic RAM.  A complex analog device emulating a digital bit storage
matrix.  Information is stored as minute charges on minuscule capacitors
which must be read and rewritten (Refreshed) at intervals to account for
charge loss due to bleed off (leakage).  Introduced by IBM in 1971.

>Drive.  As is "Tape Drive" or "Disk Drive".  The peripheral subsystem (with
controller) using the media mentioned.

>Driver.  An interface routine used to control ("drive") a peripheral device.

>Drop.  A Telco term for a subscriber's telephone line/telephone set (origi-
nally a wire "dropped" from a telephone pole to his house).  Adopted by ADP
to mean a terminal on a master/slave party line (See Multi-Drop).

>Drop Out.  A temporary, sharp reduction is signal level as if the channel
hit a pothole.

>Drum Plotter.  A type of graphics plotter that moves the paper to provide
one axis of motion and moves the pen to provide the other.  Originally the
paper was attached to a large drum rather like in a FAX machine.  Later the
paper (often with pin feed edges) was fed over a smaller drum as in a type-
writer.  HP's pinch wheel design eliminates the drum and substitutes an air
bearing.

>DSP.  Digital Signal Processing.  A rapidly evolving analog specialty using
digital computers both for analysis and analog device emulation (See Digital
Filters).  See FFT.

>DTE.  Data Terminal Equipment.  What RS-232-C folks call your terminal.
Terminals are supposed to have MALE plugs and send on pin 2.

>Dump.  A large quantity of information, frequently unsorted, printed or
displayed.

>DUT.  Device Under Test.

>Dynamic.  Said of devices and processes, particularly RAMs (See DRAM).  A
device or process which can not be halted and restarted without loss of
informa- tion or function.  For example, a CRT must be continuously repainted
(Refreshed) or the image fades.

>Dynamic Range, ATE.  The range in which valid measurements can be made,
which is basically, the range between the Noise Floor and the largest signal
measurable.

                                   -E-

>EBCDIC.  Extended Binary Coded Decimal Interchange Code.  Any of several IBM
8 bit codes originally developed for punched card Tabulators.  Later used as
a scheme to enforce incompatibility.  Never popular in data communications
(except in BiSync) as it lacks a parity bit.

>Echo.  The process of returning (usually from a host computer) text sent out
as a visual verification of circuit operation.  AKA Echoplex.

>ECMA.  European Computer Manufacturing Association.  The EC equivalent of
ANSI.

>EDAC.  Error Detection And Correction.  See Also Hamming Code and Forward
Error Correction.

>EDI.  Electronic Document Interchange.  That portion of the CALS effort
dealing with the exchange of technical documents, drawings, etc. needed to
specify a part/module/system.  Since EDI parallels a similar ISO effort and
the ANSI PDIS (Parts Design Information System) effort, EDI will probably be
(at least partly) successful.  EDI's use of SGML, however, is unwise.

>EISA.  Extended Industry Standard Architecture.  The "Gang-of-Nine" (led by
Compaq) answer to IBM's MicroChannel Architecture (MCA).  EISA is based on a
32 bit "AT" style bus/board arrangement much favored by "drop-in" board
vendors.  MCA, on the other hand, uses a smaller card w/ surface mounted
devices and a complex distributed control scheme intended to discourage
reverse engineered clones (it worked).  EISA is also about 65% faster than
MCA (33 vs 20 Mhz).  EISA is recommended.  MCA is not.

>Embedded Servo.  Said of hard disk systems.  A positive head positioning
system based on control ("servo") tracks permanently recorded on the disk at
fabrication.  Allows closer track spacing.  When multiplexed with normal data
tracks, the servo tracks are said to be "embedded".  Implies a high perform-
ance head positioner (See Voice Coil Actuator).

>EMI.  Electromagnetic Interference.

>Emulate.  A $5.00 word for "Acts Like".

+ENIAC.  Electronic Numerical Integrator And Calculator. The world's first
(unclassified) electronic computer.  Started by the US Army at U of Pa
(1943). Completed 1946.  A huge machine, ENIAC weighed 30 tons, contained
18,000 tubes plus 1500 relays (for RAM) and burned 130 KW of power (enough
energy to melt its weight in ice each hour).  Throughput was about 0.005
MIPS.  ENIAC originally was programmed via plug boards, i.e., it had to be
rewired for each problem.  The designers of ENIAC spun off into their own
company to build and market the UNIVersal Automatic Computer (UNIVAC I).
Shortly after their first sale (to the US Census Bureau), Rand Corporation
bought them out.  Later Sperry did likewise to Rand.  UNIVAC was the first
commercially sold mainframe and remains one of IBM's more successful rivals.
See Also ABC.

>ENQ/ACK.  Enquire/Acknowledge.  A master/slave character-oriented protocol
used by Hewlett-Packard and few others.  Under this scheme, the Host tells
the terminal (slave) to send using the ENQ character (^E).  The slave sends a
data block (if it has one to send) ending w/ an ACK character (^F).  When the
Host sends, it streams out a data block ending with an ENQ.  The slave an-
swers w/ an ACK when it can accept more data.  This is a "Block Mode" proto-
col well suited for transaction processing and polled-multi-drop links.  It
can not "Flow Control" ala X-ON/X-OFF once a terminal has been enabled to
transmit.  Likewise, a terminal can not transmit unless it receives an ENQ.
HP-3000's rep as a nasty interconnect problem is mostly the ENQ/ACK protocol.

>EOF.  End Of File.  CP/M & DOS used a ^Z.  Unix uses ^D, but does not post
it into the file.

>EOT.  End of Tape.  Usually marked by a shiny metallic sticker or a hole
punched through the tape itself.   Also "End of Text" (^D in ASCII).

>Ergonomics.  A $5.00 word for "Human Factors".  Is concerned primarily with
physical layouts.

>Escape Codes.  See ASCII and X3.64.

>ESD.  Electrostatic Discharge.  Specifically, static charges that build up
on people and components during normal shipping/handling and assembly/repair
of circuit boards.  Any time the relative humidity is below 35%, simple acts
like blowing dust off a circuit board or running your fingers through your
hair can create voltages lethal to MOS/CMOS microcircuits.  Liberal use of
anti-static spray ("Downy" Fabric Softener in water), "Leashes" (grounded
wrist bands) and modified work methods are required.  Inattention produces
the gaping craters on photomicrographs of blown  microcircuit (the Silicon
was literally blasted away).

>Exception Handling.  The new "Uptown" name for ON ERROR trapping.

>Expert Systems.  An almost trivial form of artificial intelligence (AI)
based on the analytical methods of one or more human experts (wired into
software). Already a proven technology in geology and medicine, this is a
growth industry.

--> Update 88: Still a "Buzz Word", Expert Systems have acquired a rep for
poor performance, or as one analyst put it: "They just don't work."  That
may be a bit harsh since the failure is human: The inability to reduce to
rules processes of the human mind and the inability of human "Knowledge
Engineers" to accurately evaluate and capture "expert" analytical processes.
Generally, an Expert System does well what humans do badly (repetitive,
mechanical processes within a limited knowledge environment (such as photo-
recon analysis)) and badly when the experience base (learning curve) is large
and the information to be  processed is incomplete, contradictory or flawed.
Good Expert Systems, like experts themselves, are hard to find.

                                   -F-

>Fall Back.  Degraded operating modes designed into a system to allow contin-
ued operation in the event of equipment failure.  AKA Graceful Degradation.

>Fault Coverage.  A tally of detectable "Stuck-At" faults divided by the
total number possible, generally given as a percentage: "95% Fault Coverage."
Now a questionable gauge of a functional pattern's effectiveness as increas-
ing part complexity has led to use of "Functional Descriptions" such as HDL
which, when compiled, produce a "Works Like" gate-level simulator model,
sizable portions of which may bear little or no resemblance to the
design/structure of the real- world chip/module.

>Fault Group.  The smallest subset of replaceable parts that a given test
method can identify as containing a specific fault.  At the system level,
these boards/ modules are replaced as a group to quickly restore system
operation.  Never as precise as predicted, fault isolation test methods
assume a single (or disjoint) fault situation, which often is overly optimis-
tic.  Large fault groups increase the removal/return of working parts and
increase support costs.  Small fault groups may demand greater resolution
than the test method can actually provide leaving the user on his own with
little or no guidance.

>FAX.  Facsimile.  A scheme for sending pictures (originally photographs, the
so called "wire photos" found in newspapers) via telephone using a rotating
drum and a screw arrangement to scan the image.  Now used for business corre-
spondence and weather maps.

>FDDI.  Fiber Data Distribution Interface.  An evolving 100 Mbs fiber-optic
LAN standard.  Uses a Dual-ring Token Passing layout that allows up to 500
nodes spread over 60 miles w/ separations up to one mile.  By this defini-
tion, FDDI is a WAN standard.  ANSI X3T9.5-1986 (Draft)

>FEC.  See Forward Error Correction.

>Feedback.  A recirculation of a portion of the output energy of a system
back into the input port (sometimes unintentionally).  One of the analog
engineer's most powerful tools, feedback forms the basis of the Analog Com-
puter. Depending on the phase of the energy recirculated, feedback may tend
to destabilize the system (causing oscillation) or to reinforce stability and
reduce distortion at the expense of circuit gain (so called "Negative" feed-
back).

>FEM.  Finite Element Modeling.  See Finite Element Analysis.

>FET.  Field Effect Transistor.  A voltage activated, high impedance device
similar to the Vacuum Tube in operation.  Carriers enter the active channel
via a "Source", are flow-controlled by a "Gate" electrode and exit through a
"Drain".  The carrier may be either electrons (N-Channel) or holes (P- Chan-
nel).  The channel itself may be "Normal ON" (Depletion Mode) or "Normal OFF"
(Enhancement Mode).  The Gate may be insulated via an oxide layer (IGFET) or
be a reversed biased PN junction (JFET).  Discrete FETs find applications in
Satellite Dishes and power controllers.  FETs also form the basis of "Analog
Switches" (w/ ON/OFF ratios of 10^5 being common).  IGFETs form the basis of
MOS and CMOS microcircuit technology.

>FFT.  Fast Fourier Transform.  A special case of the general Discrete Fouri-
er Transform (DFT) in which the number of data points taken is a natural
power of two (usually 256 or 1024).  The Fourier Transform is an implementa-
tion of the Fourier Series, a mathematical technique for representing any
waveform as the sum of pure sine wave signals of specific amplitude, frequen-
cy and phase.  The output of an FFT transformation is said to be in the
"Frequency Domain", a particularly useful format.  FFTs may be used for
analysis much as a Spectrum Analyzer is used or as part of a DSP algorithm.
The Inverse Fourier Transform (IFT) exists.

>Fiber Optics.  Specifically, the hair thin optical waveguides ("Light
Pipes") used to transmit visible or infrared light.  Now includes the light
sources, detectors, cables, connectors, splices, etc.  A viable alternative
to coax (See Coax), which is installed and handled in much the same manner.
Wideband. Immune to EMI, ground loops, Tempest. Difficult to "wire tap"
without detection. Recommended.

>FIFO.  First In/First Out.  A Queue.

>File.  A stream of bytes stored somewhere under some name.

>File System.  The supporting data structures, directory structure, and
associated files that reside on one or more mass storage volumes.  Although a
File may be of any length, File Systems frequently allocate storage space in
"Blocks" or "Clusters" involving .5K-2K byte areas.  Thus, a DOS .BAT file of
20 bytes "fills" a 2,048 byte "Cluster" on a PC-AT's hard disk.  (1,024 bytes
on most Unix machines).

>File Locking.  A necessary feature on a shared resource system which pro-
vides protection against two users attempting to modify the same file at the
same time.  Prior to a write cycle, the user must compete for and obtain
control of the file (i.e. "lock" it).  On completion of the update, the file
is released ("unlocked") allowing others to compete for the right to write.

>Filter.  A process which accepts text from stdin and writes to Stdout.
Implies a non-interactive process.  See Also Pipes and Stdio.

>Finite Element Analysis.  A technique for simulating the bending, deforma-
tion and stress characteristics of mechanical parts and assemblies. Based on
a solution to the classical paper folding problem, this method distributes
points (nodes) throughout the object to be analyzed, joining them into a web
of triangles (suggested by the folds in a sheet of paper).  By computing the
forces, displacement and stresses at each node, the response of the overall
object is predicted.  May be adapted to other situations such as Thermal
Analysis (the study of heat flow).  Useful.  Tends to require large comput-
ers.  Developed originally under US Navy contract.

>FIPS.  Federal Information Processing Standards.  Once the predominant
computer standards (1960's era), FIPS have faded to "me, too" status in
recent years. Generated for DOD by NBS, FIPS are supposed to direct the
thrust of Government computer specifications.  With the rise of Posix and
GOSIP, both performance standards, FIPS may enjoy a rebirth.

>Firmware.  Software "burned" into ROM.

>Fixture.  The physical and electrical interface between the ATE and the
device under test.

>Flatbed Plotter.  A type of graphics plotter in which the paper is attached
to a flat platen and a pen is moved across the stationary paper to construct
the image.

>Flip-Flop.  A single bit static memory cell (2 stable states).  Also called
a "Latch".  After a long search, IBM patented a "Tri-Flop" (3 stable states),
which proved to be a flop.

>Floating Decimal.  A variation of Floating Point Math (See Below) in which
the round-off error is controlled such that base ten (decimal) fractions
compute precisely.  This allows direct comparison of computed REAL numbers
and the use of the language directly for business purposes.  Part of the ANSI
BASIC-83 standard.  The lack of being a major flaw in Fortran, Pascal, C and
ADA.

>Floating Gate.  The insulated electrode suspended between a "normal" gate
electrode and the active FET channel in a UV-PROM.  Applying a long, slow
high voltage pulse to the normal gate "burns" in a permanent charge on this
insulated electrode.  Exposure to Ultra-Violet light "rubs out" this charge,
allowing the PROM to be reprogrammed.  The "burn" process depends on quantum
mechanical "Tunneling" to trap electrons on the Floating Gate.  The UV light
generates hole-electron pairs in the oxide insulating layer allowing leakage
across a barrier that otherwise would retain the trap charge for as long as
ten years.

>Floating Point.  Any of several schemes for representing decimal numbers as
the product of two raised to a power and a normalized fractional number.
Originating w/ Fortran, floating point spelled the end for the analog comput-
er and for numerous other schemes for doing decimal math via BCD techniques
as was done in mechanical calculators.  The scheme used in Fortran IV was
long a defacto standard and worked like this:  The sign of the decimal number
is separated into a flag bit and the number itself made positive.  The number
is then "normalized" by taking the LOG base two, keeping only the integer
portion of the LOG and adding one to it.  The decimal number is then divided
by two raised to that power (via shifts right/left).  The resulting number is
a fraction ranging in value between .5 and 1.0 (i.e., the highest bit is
always one).  To avoid using a sign bit in the powers value (the "exponent"),
the value 128 is added (so called "Excess 200" notation as 128 is '200' in
the Octal system) so that exponent values range from -127 to +127 (about
10^+38) for an 8 bit representation (an "octet").  DEC (and IEEE) assemble
this information for storage in the following order: The sign bit is the MSB
of the first word.  The exponent octet follows.  The first bit of the frac-
tion (which is always a one) is dropped ("hidden") and the rest of the frac-
tion tagged on behind the exponent octet.  The combination is then divided
into words for storage.  For single precision REAL numbers, the fractional
part is 23 bits long making the combination to be 32 bits in length (so
called "32 bit Floating Point").  Since it is not possible to determine the
difference between zero and a number exactly equal to one half (due to the
"hidden" bit), zero is defined as a combination having no bits set, a good
choice since testing the first 16 bit word of the combination as an integer
can establish both the sign of the decimal number and that it is nonzero, a
convenience.  Obviously manipulating floating point numbers is complicated,
but most processors (such as the PDP-11) include floating point constructs in
their instruction set (to facilitate handling Fortran) so that most of the
real labor is accomplished in microcode (which is fast).  Even so, floating
point math is the slowest arithmetic operation of an ALU.  Hardware Floating
Point has long been used to "accelerate" program execution by carrying out
the rules of floating point computations in specially designed hardware which
can easily accomplish a 6-8 times speed gain over straight microcode.  Be
aware that variations do exist both in the size of the exponent/fraction bit
split and in the order of assembly for storage (IBM, for example, places the
exponent octet first to allow manipulation via byte level memory fetches).

>Flexible Disk.  A popular mass storage scheme using a circular sheet of the
same material used in making magnetic recording tape (held inside a padded
envelope).  First found (1973) in the 8 inch IBM 3740 format (single sided,
single density), floppy disks now cover a range from  8 inch to sub 4 inch
and to quad density (double sided, double density).  Except for the original
IBM format, there are no standards.  Recording/playback involve a rubbing
contact that wears both the head and the rotating media.

>FLOPS.  Floating Point Operations per second.  A measure of computer system
speed.  FLOPS are more important to scientific users than MIPS.

>Flow Chart.  One way of detailing program logic.  Limited information densi-
ty. Frequently sprawling out beyond comprehension.  Useful for individual
algorithms, but not for large processes.

>Flow Control.  The management of telecommunications link traffic so that
none is lost.  See X-ON/X-OFF and ENQ/ACK.

>Flush.  To force a buffer to dump its contents.  Implies that the informa-
tion is not lost.

>FM.  Frequency Modulation.  A method of impressing information on a carrier
signal by changing (slightly) the frequency of the carrier wave.  This re-
sults in a wideband "splash" of sidebands.  Used in flexible disk systems in
both the basic (FM) and modified (MFM) forms.

>FORTH.  A "roll your own" language which consists of segments of executable
assembly language separated by headers.  Each header has a "KeyWord" and a
link pointer which points beyond the end of the assembly language segment (at
the next KeyWord).  Involves a discipline for passing values via stacks.
Originally created by N.More to control a telescope at Kitts Peak, Az.  Uses
RPN for mathematics.  Tagged as "The Unfinished Language" by users. Fast.
Easily customized.  Threaded.  Powerful.  Potentially deadly.

>FORTRAN.  Formula Translator. A language introduced in 1954, first run in
1956 (on an IBM 704) .  Currently available in two major versions, FORTRAN-66
(introduced in 1966) and FORTRAN -77 (introduced in 1977).  The latter bor-
rows freely from BASIC, e.g., includes string variables.  Compiled. Card
image oriented. Batch.  Fast.  Very powerful for situations involving numeric
data handled in array form.  Has a particularly powerful construct ('CALL')
for accessing either previously compiled subprograms or assembly language
object code w/ parameter passing.  File manipulation capability in -66 limit-
ed.  Uses LUNs.  Frustrating to write and upgrade.  Antique.  However, there
is more Fortran Code in operation world-wide than all other languages com-
bined (estimated to be 83% of all Code in 1987).  Continues to evolve and
improve w/ the -89 version.  The language of choice by Private Industry.

>Forward Error Correction.  Any of more than 50 schemes for detecting/fixing
bit errors in a serial data stream w/o ARQ (retransmission of busted data
blocks).  All depend on algorithmic pre/post processing and the inclusion of
"redundant" bits in the data stream (trading channel throughput for noise
tolerance).  Low speed data generally uses "Convolution" techniques (bits are
compared to previously sent bits in a sliding window).  There is a trade-off
between channel throughput and the amount of processing involved (more extra
bits, less processing needed for the same noise tolerance).  Generally modest
processing requirements, low delays (in terms of bit intervals), low storage
requirements and good burst error removal (5-6 bits typical) but high channel
throughput loss (expressed as effective/raw throughput) w/ 3/4 to 1/2 being
typical.  Some Convolution schemes are: Viterbi, Feedback, Sequential and
Trellis Coding.

  High speed data (>100Mbs) suffers more from burst errors and usually uses
"Block Coding", a technique originated to improve the performance of Disk
Drives, which can reconstruct bursts up to 512 bits long.  Longer delay times
(at least twice the block length), higher processing and storage requirements
but lower throughput reduction (15/16 to 7/8 being typical).  The Reed-Solo-
mon technique is a Block Coding scheme.  Moderate speed data may use a varia-
tion of Convolution called "Interleaving" in which the transmitted order of
bits is rearranged (thereby "splattering" long error bursts), trading in-
creased storage/delay requirements for simplified processing.

  FEC dramatically improves a "Dirty" channel such as a Dialup Telephone line
(where error rates of 1/100 are not unusual) making it a high quality link
(BERs of 1/1E5 or better).  Most cost effective where BERs are high (where
ARQ works poorly).  Basically a link technique, FEC is transparent to the
data handled, which may employ ARQ as well.  Impressive.  Witnessed a demo at
AGA Hawaii where an experimental IBM rig printed error-free data through
noise that completely masked the modem tones.

>Four Wire.  A telephone channel split so that one pair carries the send
conversation and another pair carries the receive conversation.  Better
suited for high quality services such as high speed data.

+Fourier, Jean.  (1768-1830)  A French mathematician and Physicist who, in
the course of his work investigating heat flow, had the nerve to expand
complex mathematical expressions into an infinite summation (series) of pure
sine waves of specified phase and amplitude.  The publication of this tech-
nique set off a firestorm of debate which lasted more than a hundred years,
finally being laid to rest in 1933 when a definitive body of proofs and
conditions were published.  By that time, experimenters had firmly estab-
lished the validity of the technique in describing all manner of waveforms,
especially those associated w/ electronics and acoustics.  See Also FFT.

>4GL.  Fourth Generation Language.  Whatever that is.  APGs are generally
hyped as being 4GLs, but fail outside very narrow range of (usually DBMS)
applications.  OOLs such as C++ are considered 4GLs.  ATLAS is trying to
pass itself off as a 4GL, which is patently ridiculous.

>Free List.  A map of unused data blocks on a disk system.  As files are
created, space is removed from the Free List.  As files are deleted, their
area is added to the Free List for reuse.
>Freeware.  Software (usually of trivial commercial value) provided to the
General Public at No Cost "As Is" w/o warrantee or support.  Usually  Copy-
righted to prevent Resale for Profit, Freeware may legally be duplicated,
distributed and used so long as the Copyright Notice remains attached.
Sometimes of surprising quality/utility.  Kermit is Freeware.

>FSK.  Frequency Shift Keyed.  Data transmission via a modem that shifts
between two distinct tones (a Mark and a Space) as the bit stream shifts
between Ones and Zeros.  Used for low speed modems (Bell 103 types) up to
about 300 baud.

>FTAM.  File Transfer Access and Management.  An ISO Network applications
level protocol comparable to FTP in TCP/IP.  AKA ISO 8571.

>Full Duplex.  Send or Receive any time both ways.

>Future Shock.  An observable human response to the accelerating rate of
change brought about by the knowledge explosion.  The sum total of human
knowledge has doubled over each of these intervals:

1200-1600-1750-1850-1903-1948-1956-1961-1965-1968-1971--> Every Odd Year
Since.

  Although the growth rate has stabilized recently (due to limits in the rate
of information flow), the impact to everyday life is just now catching up.

                                   -G-

>Gate.  The smallest circuit element capable of performing a binary math
function.  Complex circuits are often discussed in terms of their "equivalent
gate count".

>Gateway.  Said of a type of "black box" found in LANs.  A special form of
bridge that interconnects two (usually non-compatible) LANs.  May include
passwords or other such security measures.

  According to ISO, a device that interconnects two LANs by passing through
everything it hears is a "Repeater" (contains OSI layers 1 & 2 only). If the
device can perform address discrimination ("Routing"), it is called a
"Bridge" (contains layers 1 - 3).  If the device also performs protocol
conversion, it is a "Gateway" (contains layers 1 - 4).

>GCR.  Group Code Recording.  A 1971 technique to increase the information
density on magnetic tape from 1,600 to 6,250 bpi.  Basically an FEC technique
similar to those used in Telecommunications.  First used on the IBM 3420
Series tape drives, GCR is currently generating interest in the computer
community at large primarily due to development of high performance "Short
Column" tape drives.  GCR does not use "Read-After-Write" making the us of
known good ("Certified") tapes mandatory.

>Gender Mender.  Also called a "Goof Plug". A pair of RS-232 connectors wired
back to back so as to interconnect two devices/cables using the same gender
of connector (both males or both females).

>GKS.  Graphics Kernel System.  A standard covering graphics software, lan-
guage interfaces and the like originated in Germany by the Deutches Institute
fur Normung (DIN), the German equivalent of ANSI.

>Glitch.  Originally, an unwanted pulse of short duration that causes mis-
chief in digital logic circuits.  Now used much as the older term "gremlin"
to signify an unknown cause factor.

>Gold Module.  A rigorously tested, known good device to which all others are
compared.  AKA Correlation Module.

>GOSIP.  Government Open Systems Interface Profile.  An NBS effort to inte-
grate the ISO OSI model (for communications) and the SVID (for User inter-
face).  A good idea being done by some very good people (they also originated
Posix) and a very good name, too.  It is expected to become VERY widely used,
which isn't surprising as nothing spreads like GOSIP.  GOSIP will become a
FIPS.

>GPIB.  General Purpose Interface (or Instrument) Bus.  See IEEE-488.

>Graphics.  Literally pictures. Specifically, diagrams, mathematical curves,
and CRT images.  May be in vector form (line drawings) or raster form (dot
patterns).

>Graphics Tablet.  A small, flat area which can detect the location and
motion of a stylus.  Originally intended for use as a graphics digitizer, now
often used as a joystick replacement.

>Gray Code.  A BCD code with the property of having only one bit changing as
the digits are counted up or down.  Useful for optical encoders.

>Guard.  A Faraday shield wrapped around and insulated from an instrument
such as a DVM.  Most effective when extended to the point of measurement
(where it joins w/ the Lo measurement lead), a guard should NEVER be left
floating.  If precision is not required, connect it to the Lo terminal at the
instrument.

>GUI.  Graphics User Interface.  A Visually Flashy Icon-Oriented pixel-level
Windowing method generally associated w/ Apple's MacIntosh (the "Look & Feel"
of which came from the failed Xerox "Star" Workstation).  OS/2 & MS-Windows
are GUIs.  User Friendly, GUIs tend to be Programmer Hostile, CPU intensities
and RAM Hogs.  Unix (and Turbo C) do text Windowing ala "curses", a much
faster technique.  X-Windows is also a GUI.

                                    -H-

>Hacker.  According to Webster: "(1620) A person unskilled or inexperienced
in a particular activity."  In the early 1970's, Data Processing profession-
als hung this handle on "non-believers" (non-Computer Scientists), particu-
larly those associated with microcomputer programming.

---> Question: Now that Micros are Mainstream (and Mainframes Aren't), what
do we (the Majority) call the CS diehards?  (Read Quoted Text Above).

>Half-Duplex.  Either Send or Receive (not both) at any one time. Awkward due
to turn-around problems.

>Hamming Code.  One of a class of "Lossless" Codes having the property of
finding/fixing single bit errors within a coded data word.  Widely used in
EDAC RAM, especially w/ systems having 32 bit (or larger) data words as the
required overhead decreases w/ increasing word size (8 bits needs 4 extra
bits, 16 needs 5 but 32 needs only 6).  Hamming EDAC is easily accomplished
in gate level hardware.  Another "Lossless" Code is the "Golay" Code some-
times used in communications as an elementary form of FEC.

>Handshake.  An exchange of signals (flags and strobes) between a sender and
a receiver that control the flow of information.  Implies a byte by byte
positive control scheme.  Implies use of metallic wires.  Example:  GPIB.

Update 88 ---> Software Handshaking is a logical extension of the hardware
form (above).  A "Handshake" differs from a "Semaphore" or "Flag" in that it
can pass significant information between participants, not just a
"True/False" or numeric value.  Some Handshake schemes are quite elaborate.
The term predates computers by about a thousand years, being used by the
Mason's Guild since the Middle Ages.  Most fraternities (including the Mason-
ic F&AM) continue the tradition of an identifying "grip".  Formal rules
define the meaning of the signals exchanged, i.e., a "Protocol" is involved.

>Hard Disk.  A mass memory system for computers based on a rigid aluminum
platter coated with a polished ferrite above which is suspended a read/write
head bucking aerodynamic lift against strong springs to achieve a very narrow
gap (about 1/30 the thickness of a human hair).  Under normal conditions, no
actual contact occurs (See "Head Crash").  Nonvolatile. Fragile while in
operation and subject to contamination due to dust and tobacco smoke (See
"Winchester Disk").  Faster than flexible disks.  Many variations including
multiplatter stacks & high performance controllers. Information density of
disk systems has doubled every three years for the past decade with no end in
sight.  AKA Spinning Storage, Spindle or simply "Disk".  The keystone of
modern large computers providing the basis of their performance and the
primary limitation to their actual throughput. (See DOS).

+Hard Disk, History of.  The aerodynamically suspended (flying) head predates
disk technology by nearly a decade having been developed w/ the magnetic drum
which first appeared on the IBM 650 in 1948.  Attempts to build a drum memory
w/ a single movable head encountered serious manufacturing problems associat-
ed w/ holding ultra-precise surface tolerances on a curved surface.

  Surface smoothing technology for flat surfaces was a well developed art and
designers envisioned a flat "drum" rather like a phonograph record w/ the
head on a pivoted "tone arm".  Underestimating the stresses involved, the
first prototype flew apart w/ explosive force injuring several bystanders.
Rebels in a basement workshop revived the project (which was officially
canceled) producing a much beefed up version successfully demonstrating the
breakthrough nature of disk technology.

  First marketed in 1957 for the IBM 305 system as a 50 platter stack of 24
inch disks holding about 5 Mb  (50,000 "Punch Cards").  These early disks
used hydraulic actuators for head positioners controlling them w/ solenoid
valves driven by thyratron tubes.  Tracks were defined by mechanical detents
similar to TABs on a manual typewriter.  Used until the middle 1960's when
solid state controllers and stepping motors appeared.

  Head positioners were of the "Open Loop" type until 1971 when IBM intro-
duced "Servo Tracks" (Closed Loop) system using permanently recorded "guide"
tracks on one surface to control head positioning. Doing so signifi- cantly
improved thermal tracking allowing more tracks and removable disk packs.

  Conventional Flying Heads are called "Ramp Loaded" or "Dynamically Loaded"
since the heads are physically retracted until the disk spins up.  An IBM
project named "Winchester" (its goal of 30 Mb on 30 track suggested the 30-30
rifle).  What resulted was something new:  A sealed Hard Disk w/ a lubricated
surface (to allow the heads to "Soft Land" and park on power down).  Marketed
in 1973 in as 14 inch format, Winchester drives established themselves as
being of unusually high capacity, high reliability and exceptionally durable.

  IBM's "Piccolo" project brought an 8 inch Winchester design to market in
1979, plus non-IBM vendors brought forth similar OEM versions targeted at
microcomputers.  For the general public, this was the first "Winchester"
drive.  Coming on the heels of the floppy disk revolution , this catapulted
micros into the serious machine category in the business/scientific world.
The 5.25 inch Winchester appeared in 1980 (from Seagate) targeted specifical-
ly at micros.

  A large part of the success of hard disk technology is associated w/ the
high degree of intelligence embodied in the disk controller.  Our Traditional
expections are based on IBM's "Merlin" controller which was the subject of a
long, bitter and costly lawsuit involving the theft of trade secrets. Regard-
less of the merits of the case (IBM eventually won) the effect was to migrate
information about Merlin into the public domain allowing hard disks vendors
to build on a proven design.

  Disks have maintained an astounding growth rate in information density
averaging a three-fold increase every three years for over a decade.  Each
time a physical limit has been reached, disk technology has stepped aside and
bypassed it.  Current trends (6/84) are to non-ferrite coatings either plated
or sputtered onto the aluminum substrate.  Improved information coding/
processing and pre-amps on the head assemblies has enabled use of smaller
signals, smaller head/surface gaps, smaller (thin film) heads and overall
higher information densities within the track itself.  Improved positioners,
closed loop servos, embedded servo tracks and like techniques reduce the
"guard band" space between tracks allowing more tracks/surface.

  From the beginning, Hard drives depended on synchronous (3,600 rmp) motors.
Locked to the 60 Hz line frequency (which is carefully controlled by power
companies to allow load-sharing), Hard Disks experience a "Rotational Laten-
cy" of about 16 mS.  Track buffering helps, but access times under 10 mS are
rare.  Where cost is no object (but performance is), broadsiding bits (on
separate surfaces) allows megabyte/s data burst rates, but do nothing about
rotational delays.

  Lap-tops w/ hard drives have no power line to lock to.  At first they used
a simple 60 Hz inverter and a conventional Hard Drive, a power hungry combi-
nation.  Improved controls allowed DC driven Hard Drives which, it turns out,
aren't necessarily driven at 3,600 rpm.  PC Hard Drives w/ 4,800 (even 6,000)
rpm rates are marketed.  Reflecting the new reality of Computers, IBM is
delivering a Mainframe Hard Drive spun at 4,200 rpm, providing 40% faster
access (loudly hyped as a "Breakthrough").

>Hard Error.  An error introduced in data that is not correctable.  An error
caused by a hardware failure.

>Hard Reset.  A "Warm Boot".

>Hard Sectored.  Said of flexible disks.  The dividing lines for the pie-
shaped segments ("sectors") of the disk are marked by holes punched in the
media, i.e., the dividing lines are "Hard."  The opposite (and more common)
situation is the "Soft Sectored" disk which uses timing to set the sector
boundaries based on a single timing hole punched in the media.

>Hardware Floating Point.  AKA Floating Point Accelerator (FPA) or "Math Co-
Processor".  A coprocessor running in parallel with the main CPU. Floating
point instructions are recognized and executed in hardware.  Since hardware
is faster than software, the speed gain is dramatic.

>Hardware Handshake.  AKA EIA Handshake.  The control of data flow on a
serial (RS-232) link by level shifts on mutually agreed on pins.  Despite the
"EIA" handle, there is no standard.  Almost universal use of UARTs (which
include a level controlled gate on the output and a "Buffer Full" flag on the
input) has established a defacto operating standard ala X-ON/X-OFF using flag
pins. DEC seems to favor using RTS/CTS.  Other use DTR/RSR.  Other combina-
tions (including use of pin 19) exist.  Interestingly, a true RS-232-C port
(as is found on many mini's) will not hardware handshake and can not be made
to do so.

---> Update 89:  EIA RS-232-D legalizes RTS/CTS hardware handshake.

>Hash.  Said of Pointer Routines.  A class of algorithms that speed list
searches by computing a starting point based on the entry text itself.  The
effect is to "splatter" entries across a data list.  Often used in disk
directory systems.  So named for the "hash" made of the original text.

>Head Crash.  Said of hard disk systems.  The most feared failure mode.
Nearly always results in data loss.  May completely destroy the recording
media.  Caused by loss of the roughly one micron wide gap between the sta-
tionary head and the rapidly revolving disk.  Nearly always caused by dirt
particularly tobacco smoke.

>Headend.  The frequency shifting unit found in a Mid-split broadband LAN.
May include monitoring/testing equipment.  Usually located at some central-
ized point.  A single point of failure for broadband LANs.

>Hen & Piglets.  A simple multitasking scheme based on a monitor program (the
"Hen") which is called at intervals by each of the executing programs (the
"Pig- lets") so that system resources can be shared.  Easily accomplished
inside a normal program, this scheme has no protection against a task going
Whole Hog.

>Heuristic.  Any "U-Drive" scheme of problem solving that doesn't solve the
problem, but helps you do it yourself (assuming you know how).  Popular w/
Logic Simulators ala LASAR, TEGIS and LOGOS.

>Hex.  Hexadecimal.  A scheme for representing all combinations of 4 bits by
the numbers 0-9 and letters A-F.

>Hierarchical Directory.  A directory (or file system) structure in which
each directory may contain other directories as well as files.

+High Level Languages, History of.  Languages tend to "Fuzz" into being over
a significant period of time, perhaps as long as a decade (in the case of
Pascal), although some spring into being very quickly (like Prolog).  The
intent here is to profile the overlap and cross-pollination of evolving
languages.

  1954  Fortran I Announced (First HLL).
  1956  Fortran I Released (on an IBM 704).
  1958  ACM initiates ALGOL effort.
  1959  DOD initiates COBOL effort.
  1960  ALGOL-60 Released.
  1961  COBOL-61 Released.  (First widely used version).
  1962  Fortran IV Released.
        BASIC Introduced (at Dartmouth).
        SNOBOL Released by IBM.
  1965  PL/1 Released.
        APL Released.
        BASIC Released.
 c1965  LISP Introduced.
  1966  ANSI Fortran-66 Standard.
  1968  ANSI ALGOL-68 Standard.
  1971  Pascal Introduced as a Teaching Tool.
        'C' Development Starts.
        Prolog (an AI Language) Released.
  1974  ANSI Minimal BASIC Standard. ("Tiny BASIC")
  1975  'C' published in Bell System Journal.
  1976  HP Introduces 'Rocky Mountain' BASIC on 9845A.
        MicroSoft Introduces 'MicroSoft' BASIC on MITS Altair.
        DOD-1 (Ada) Project Begins.
  1977  ANSI Fortran-77 Standard.
        ANSI MUMPS-77 Standard.
        FORTH-77 Released.
  1978  'C' Released w/ Unix.
        ANSI ATLAS-78 ATE Language Released.
  1979  DOD-1 Standard Frozen.  Renamed 'Ada'.
        USCD Pascal Released. (First widely used version).
        FORTH-79 Released.
  1980  Smalltalk-80 from Xerox.
        IEEE ATLAS-81 Upgrade.
  1983  Modula-2 Released.
        ANSI Pascal-83 Released.
  1984  First Ada Compilers Validated. (Language effectively Released).
  1985  C/ATLAS-85 Released.
  1987  ISO BASIC (the Full Language) via ECMA.
        C++ (An Object Oriented Language) Published.
  1988  Ada Fails NASA/DOD Posix Tests.  NBS Tasked to "Fix" it.
  1989  ANSI 'C' Language Standard & Standard Libraries.
        ANSI BASIC-89 Standard.  (First Full US Standard .. 25 Years Late).
        ANSI Fortran-89 Standard.

>HITS.  Hierarchical Integrated Test Simulator.  A yet-to-be successful Navy
project to create a mixed mode gate/functional level simulator.  Originally
intended to allow on-the-fly switches between model types.  Based on LOGOS,
an excellent behavioral simulator.  Slow.

>Hollerith.  The name of a type of field in Fortran IV used to simulate a
text handling capability.  Frustrating to use.

+Hollerith, Herman.  (          ) An engineer working for the US Census
Bureau generally credited w/ the invention of the punch card once widely used
in data processing.  The punched card actually predates him by almost 100
years, having been in wide spread use controlling power looms since England
adopted the design of Joseph Jacquard (1752-1834) around 1810.  (The Jacquard
Loom was an improvement of a 1750 design for a silk weaving machine con-
trolled by a punched paper roll similar to that used in a player piano.
Technically successful, it resulted in labor revolts).  Although Babbage
proposed to use punched cards to control his Analytical Engine, Hollerith is
unquestionably the first to apply them successfully to data processing.
Hollerith's cards were the size of dollar bills (which were somewhat larger
then).  His machines were used in the 1890 Census with good success.  In
1911, the company that became IBM picked up the idea as the basis of an array
of bookkeeping and tabulating machines.  The punch card sorter was patented
in 1925 and the format for the common 80 column card was frozen in 1928, 18
years before the first electronic data processing machine used them.

>Host.  Where your program is running.

+HP-9845, Significance of.  It was supposed to be a business machine.  It was
the High Water mark for ROM-based machines.  As one HP-UX instructor put  it,
"The 9845 was a Real Machine Designed by Real Engineers to do Real Work."  It
cost $20-40K, not something to invest in lightly.  It came to Market the same
year  as DEC's VAX-11/780 (1976-1985).  US production ended in 1987 w/ German
production continuing into the 1990s.  They obviously  did  something right.

  It was called "Qwert" after its built-in Full ASCII Keyboard.  Powered  by
dual  16  bit (custom) CPUs, it had 62K of DRAM,  Dual  DC-100  MiniCartridge
Drives, a built-in 12 inch CRT w/ "EGA" Graphics, a Built-in Thermal  Printer
and 4 I/O slots.  "Galleon" (HP-9845B) (1977) added two more bits to RAM  Ad-
dressing registers and featured 187K of RAM expandable to 1 Mb.  (4  "Qwert"s
to  the  "Galleon").  As a Business machine, it flopped.  As  a  result,  the
Loveland, Colorado, Calculator Division was disbanded.

  What  they  had built was a CAE Workstation.  It was  User  Friendly  (See
Same) to the extent that crashed programs could be "patched" and  "UnCrashed"
without  losing Data or ReStarting.  Its Language came to be known as  "Rocky
Mountain  Basic",  a polyglot of Basic, Fortran, ALGOL, PL/I  and  APL,  that
featured   BCD math (no Round-Off Error).  (Unlike IEEE Floating  Point,  BCD
can tally a hundred pennies and get exactly $1.00 every time).

  David Pick, a former HP employee, spun off and marketed the PICK Operating
System  (See Same) in the late 70's using a very power dialect of Basic  that
features BCD Math.  Its use is so widespread in Europe that ECMA insisted ISO
issue  a Full Basic Standard that reads like a Rocky Mountain Basic  Program-
mer's Guide.  Bill Gates Cooped at HP, founded MicroSoft and fielded MS-Basic
(later BASICA & GW-Basic) so similar to Rocky Mountain Basic that he felt  it
wise  to adopt DEC's "LEFT$/MID$/RIGHT$" string handling to avoid  a  lawsuit
(Pick did likewise).

  Meanwhile, HP lost the road map.  "Dawn" (HP-9000/520) was supposed to  be
a  "Super  9845".  It was pathetic.  When the 9845 was built,  Engineers  did
both the hardware and the software, balancing each against the strengths  and
weaknesses  of  the other.  The resulting system was a lot of  little  things
done  right  so that the combination was much more powerful than  the  modest
power of either suggests.  Not until HP's "Precision Architecture" did  com-
puter hardware & software designers actually work together again.  (Dawn's
thermal printer has a hardware Top of Form sensor which reads index holes in
the special paper to generate a signal the Software ignores.  Sad.)

  Rocky Mountain Basic lost BCD Math w/ the introduction of the 9000  Series
(1984).   For  a long while, HP tried to "Leverage" Basic Users  into  Pascal
(which  is  clearly  inferior).  They now show renewed  interest  in  Basic
(running under Unix).  The first Fully ISO compliant PC Basic is Power-Basic
2.0 (1/90), an upgrade to Borland's Turbo-Basic.  9845 BCD Basic lives  again
on the PC.

  Some of Loveland's Engineers moved to Corvalus, Washington where they
created the HP-85 (which "creamed" the 9825 instrument controller, an $8K
box) and the 7470 pinchwheel pen plotter (called "Sweet Lips").  Loveland
always took the honors for Imaginative Project Titles.  At the End, Corporate
wanted a "Galleon" Knock-off.   Graphics was stripped from the CRT (Project
"Stark"), a cheaper "Magnetic Actuation Detection" keyboard was designed
(buyers rejected "chicklet" keys) and one CPU was ripped out.  They named
their Swan Song, Project "Raven"  ("Quote the Raven, 'Nevermore'.")  HP-9835
("Stark-Raven-MAD") bombed.

+Human.  A biologically based single user, multi-tasking, multi-processor
highly pipelined parallel processing portable real-time system.  Optimized
for pattern recognition, Voice I/O and adaptation to changing requirements.
Slow. Electro-Chemically powered.  Cache RAM plus 20 minute buffer backed up
by pointer-drive Lifetime main RAM.  Foreground processing requires periodic
suspension for buffer flush/maintenance ("sleep").  Background associative
(subconscious) processes run continuously as bookkeeping, error detection and
non-indexed information retriever (Foreground often loses pointers). Pro-
grammed to make errors, evaluate actions against a knowledge-based "value
system", and "Learn".  Superior to solid-state CPUs in situations requiring
complex pattern recognition or adaptive response to unstructured situations
involving contradictory and/or incomplete information, but inferior for
repetitious, monotonous tasks.  Output must always be viewed with suspicion
as units are assembled by unskilled labor from available materials.  Deliv-
ered in two basic models up & running w/ a Lifetime warranty.

>Hybrid IC.  A composite circuit technology based on conductors silk screened
onto a ceramic substrate and fired ala pottery after which components are
mounted (including monolithic IC's).  The resulting circuit is usually her-
metically sealed, often w/ a "bathtub" style metal cap.  Never really popu-
lar, hybrid IC technology hangs onto various niches in analog (and some
digital) applications which, for one reason or another, do not lend them-
selves to monolithic technologies.

                                    -I-

+IBM, History of.  International Business Machines never wanted to build
Computers.  Fact.  Circumstances forced them to do so to Protect their
Business Machine Market Share.  Along the Way they Invented Virtually Every-
thing we Associate w/ Computers, including so much Jargon that "IBM" appears
in this Document No Less than 150 Times.

  A direct Descendent of Hollerith's Punch Card Tabulators (used in the 1890
Census), IBM began in 1911 as the "Computing-Tabulating-Recording" Company.
Unfortunately, a Rival (also a Census Bureau Spin-off) was doing quite well
selling Business Users Punch Card Systems.  Pushed to near Bankruptcy, CTR
bet everything on a New Reader/Printer introduced in 1912.

  The Read/Printer allowed CTR to sell a "Total Business Solution" (At a
Premium Price).  This hard-won lesson has carried them through two World
Wars, the Great Depression and Countless Shifts in Technology.  They Also
learned that Technology was their "Edge" in the "Business of Business".

  Though their Rival survived to become Rand, then Remminton-Rand, later
Sperry-Rand, Sperry-Univac and finally UniSys, it never seriously threatened
CTR/IBM again.

  CTR expanded into Typewriters (electrified in 1935), Tabulators (in direct
competition w/ Burroughs) and all manner of Punch Card machines.  The Multi-
Bin Card Sorter introduced in 1925 allowed Punch Cards to be Used as a Data
Base, a significant breakthrough.  The same year CTR opened a sales office
in Canada and changed its Name to "International Business Machines."

  The famous "IBM Card" appeared in 1928, just in Time for the Bottom to
Fall Out of the Stock Market.  IBM, unable to sell its machines, went into
the Data Processing Business, seeking contracts from various Government and
Research Organizations that badly needed Computational "Bang/Buck".  Out of
this experience came a new generation High Speed Tabulator/Calculator called
"Comptometers".

  IBM didn't want to be (and didn't stay) in the Data Processing Business,
but learned a valuable lesson: Speed Sells.  Against this backdrop, Atkins
approached IBM in 1936 for funding to build an Electo-Mechanical version of
Babbage's Dream Machine, the Analytical Engine (See Mark I).  He got a Million
Dollars & IBM got the Patents.  As it turned out, this was the High  Water
Mark of Tabulator Technology.

  ENIAC proved Electronics works Better than Gears & Relays (Bell Labs  built
an all Relay Computer w/ 9,000 Telephone style Relays.  It proved ten  times
slower and less reliable than ENIAC's 18,000 vacuum tubes).  IBM built and
sold several Electron Calculator designs (notably the 650 in the early 50's)
but did not follow the ENIAC-EDVAC-UNIVAC "Serial" design route for  Comput-
ers.   (In a "Serial" Computer, trains of pulses are shuttled around like  so
many boxcars.  The Major advantage is that Delay Lines (usually iron tubes
filled w/ liquid mercury) can serve as RAM).

  In a Shrewd Business move, IBM took on the enormous SAGE Air Defense
project, gaining access to MIT's "Whirlwind" Technology.  This was a 16 bit
"Parallel" Design in which Words moved along bit-parallel (as in all Modern
CPUs).  When IBM unleashed the 701 on the Business World (1953), they were in
the Business Computer Business to Stay.

  Early Machines were $20 Million Monsters needing Enormous Amounts of
Energy, Air Conditioning and Manpower.  IBM had to Bootstrap an Entire
Industry Up from Point Zero and Make a Profit doing it (No Small Feat).  They
Already had an Installed Base of Punch card Users.  These were "Leveraged"
into the world of "Automated Data Processing" (ADP).

  To Offset the Crushing Cost of Computers, IBM Leased Machines.  As they
became obsolete, they were donated to Schools.  The Schools responded w/ a
Steady Stream of Computer Science graduates firmly grounded in IBM methods.
To Businessmen, IBM provided a "Total Support" package that, more often than
not, included an On-Site Maintenance Team.  It was expensive, but IBM  suc-
cessfully justified that expense in hard-nosed business terms.  It worked.

---> An Aside: The Mainframe Environment.

  Technical Users find Mainframes to be User Hostile, Slow, Expensive and
Crude.  But Technical Users are not (and Never were) the Focus of Mainframes.
It is a Different World.

  Mainframes Applications Focus Inward, optimizing Hardware/Software to
Maximize the Throughput of the CPU.  Basically, Mainframes do Many Jobs,
Each done Slowly, to Minimize Disk Access Bottlenecks.  Emphasis is on
Accountability, Audit Trails and Crash Recoverability.  Loss of Data is the
Ultimate Sin.

  Almost by Definition, Mainframes are "One-of-a-Kind" Installations.  No
two are Alike and the Sum Total of Any Model Sold is surprisingly Small.
Each  Installation has a Sizable Support Staff and All Sites are Highly
Customized for their Specific Application.  "Patches", "Updates" and "Fixes"
are a way of  Life.

  Mainframe Software is Usually Written to Order.  The "Beta Site" is the
Customer's Machine.  GSA's 1986 report on Mainframe Software Reliability is
Sobering: Only 2% of the Software the Government Purchases Worked as Expected
on Initial Delivery.  An Additional 3% was Fully Acceptable after Minor Touch
Ups.  19% required Substantial Rework to be Fully Acceptable.  37% Required
Major ReWrite/ReDesign to be Usable even in Part.  39% did Not Work at All
and Could Not Be Made to Work.  This is a Defect Rate of 95%!!  Sad.

  Mainframes are Essentially Batch Machines.  Time Share is Possible, but
not Effective Unless a "Front-End Processor" (FEP) is used to handle the
"Chatter" & queue up Tasks ala RJE.  IBM generally splits their Systems into
"Virtual Machines", each the size of a Middle 60's CPU (today's PC-AT).  Each
"VM" Session Thinks it is a Complete CPU with Total Control of All Hardware/
Peripherals.  This Allows Divergent Operating Systems to Co-Exist on the Same
Mainframe (which is what AIX hopes to do).

  Because of their Inability to Standardize (and OEM encouragement),  Main-
frames are "Closed Systems".  Choosing a Mainframe OEM is a lot like  Getting
Married.  It is a Long Term Relationship, sometimes a stormy one, with
Rewards, Costs and Obligations.  Switching Mainframe OEMs is a lot like a
Messy  Divorce; Not sometime done casually.  This "FUD Factor" (Fear,
Uncertanty & Doubt) tends to "Lock In" Users.

---

  IBM has had its Disasters, too.  In 1964, They switched to the 360/370
Family of machines across the board.  They bet the Ranch on OS/360, a
Software project Larger and more Complex than Anything Ever Done Before.
Iron shipped on time; software was late.  Very late.  18 months late.

   After 9 months of schedule slips, IBM was in very real danger of
bankruptcy (a closely guarded secret at the time).  Management was apalled to
discover that the entire OS/360 project was a shambles.  It was "Kill and/or
Cure" time.  Coding was halted.  Planning documents were created and many,
many design hours expended before the next line of code was written.  Nearly
everything previously done was scrapped.

   Before Management intervention, the emphasis was on programmer output
(they expected 20 lines of working code per person per hour).  But nobody was
minding the store, so nothing worked together.  Shambles.  Guided by the
planning documents and rigorously tested against design specs, OS/360 slowly
evolved over the next 9 months.

   After delivery (and a long sigh of relief), IBM published a book on their
experiences noting that, counting planning, documentation and testing, the
actual productivity of each programmer turned out to be 1/10th of a line of
working code per person per DAY!

   OS/360 proved to be a Quality Product well worth the wait.  Along the Way,
IBM Invented Walk-Throughs and all the Documentation/Planning and Validation
Checks Now Embodied in MIL-STD-1696.  They also created the pastel blue color
scheme that has earned them the "Big Blue" and "Ice Blue Monster" handles.
IBM learned Another Valuable Lesson:  Don't Handle the Bytes that Feed You.

  Another Hard Learned Lesson was that Users don't Tolerate Desktop Hardware
that Breaks.  Since IBM generally provides On-Site Service, Reliability was
never an issue in Mainframes (They were Designed for Maintainability).  After
three Abortive attempts to Field a Desktop Machine ala CP/M (they bought them
all back), IBM turned loose one of their "Enterprise Groups"  w/ only One
Guideline: Do It Cheap.

  So they took Off-the-Shelf Technology, bought PC-DOS from MicroSoft and
Enticed a Mob of Third Party Hardware/Software Developers to Invest Their Own
Money in After Market Add-ons/Drop-ins.  They Announced the IBM PC in 1981.
It clobbered CP/M, CP/M-86, Apple DOS, Apple III, Osborne, TRS-80 and the
Ill-advised DEC Rainbow.  "PC" came to mean "IBM PC", a Defacto Standard.

  To Software Developers, the PC was an "Open System" (IBM wasn't Interested
in Spread-Sheets or Adventure Games).  However, Iron was another Matter.  The
BIOS resides in Copyrighted ROM.  IBM moved quickly against "Clone" OEMs.
Business Users bought IBM PCs by the Truck Load.

  In 1983, Phoenix Technology "cracked" PC ROM BIOS by Using a "Clean Team"
to "Reinvent" a functional equivalent.  They invited IBM to sue (They Didn't)
and offered Customers "Litigation Insurance" (through Lloyd's of London).
The "Clone Wars" were On!  And PCjr was Dead Meat.  Crippled by Design (128K
RAM Max and a single floppy drive), the "Peanut" was a toy costing more than
a "Real" 640K Clone.  IBM  scrapped them by the Truck Load.  Another Lesson:
Name Alone can't sell a Turkey.

  In trying to do the PC "On the Cheap", IBM accidentally created an Open
System.  This was (from their standpoint) a Major Error.  Generally, IBM
protects its Price Premium behind a wall of Proprietary Standards which are
NEVER revealed to Outsiders.  "Plug Compatible" OEMs always had to wrestle w/
untangling Product Specific features from what comprised IBM's real Stand-
ards. And if those OEMs did too good a job, IBM just changed the Standards.
Hard Ball.

  The Above practice (plus a Couple of Attempts to Run Roughshod Over ISO)
caused EC to bar IBM from Access to the European Common Market.  US State
Department Intervention struck a Compromise: IBM agrees to Formally Publish
All Inhouse Standards "within a reasonable time of product introduction."
EC agreed, but stipulated that "a reasonable time" was no more than Two Years.
(Which is why IBM just Release the MCA Standard).  IBM learned Another Lesson:
Standards in Europe have Teeth.

  We, the Technical Users, view OS/2-PS/2 as a Major Mistake.  Actually  IBM
got exactly what it wanted: A Closed System, Proprietary Hardware, No
Clones.  They had hoped for More Third Party Software, but really intended
the PS/2 to be an SAA Network Node running Applications on Remote Mainframes,
so it didn't Really Matter.  OS/2-PS/2 turned out to be less "Gee Whiz" than
expected, but they will Sell to IBM's "Captive" Business Users.

  Still, OS/2-PS/2 did NOT establish a Defacto Standard.  IBM really hoped
it would.  When MicroSoft jazzed up MS-Windows too much, IBM moved quickly to
prevent a DOS-based OS/2 Rival.  (After Bill Gates returned from the
"Woodshed", MS-Window froze for two years).

  OS/2-PS/2 has hurt IBM's Image.  Of the Fortune 500 Companies, 59% Feel
IBM has Lost its Ability to Mandate Standards.  The "Captive Market" is
getting Restless.  DEC has launched a Major Move into IBM's Private Preserve
(Business), leveraging its DECnet Connectivity into formerly "True Blue" Data
Processing Centers.  (IBM's Token Rings and AIX "Open Systems" remain mostly
Vaporware).  How serious this has become can judged by a Major Shift in IBM's
"Total Support" Policy: They Now Repair/Maintain ALL On-Site hardware, "Ice
Blue" or not.

  With a (1988) Sales Volume of $60 Billion, IBM is far from another 1912
"Squeaker".  It is 5 Times the Size of DEC, its Closest Rival.  On the other
hand, Mainframes have clearly Peaked.  IBM's current tactics of Promises,
Minimal Compliance w/ Standards, and Limited Connectivity may "Fence In"
current Business Users, but New "Marriage Partners" with open checkbooks and
a willingness to "Trust Me" may be scarce.  Even Business is Becoming a
Buyer's Market.

  Still, the Business of IBM is Business, and They are Very Good at It.

----

  And That is Precisely the Point.  We are Outside IBM's Focus because
Business Applications are Classical Computer Science and almost Nothing we do
is.  IBM Builds Very Good Iron, Solid Software and Does Very Good Work.  They
have maintained a Price Premium for "Total Business Solutions" for 7 Decades.
They Must be doing Something Right.  However, Misapplying Business Solutions
to Technical Problems can be Very Expensive.  (It doesn't Work Well, either).

>Icon.  A pictorial representation.  Implies the ability to move it as a
single entity ala Smalltalk or LOGO.

>Idiot Stick.  A short (2-4 foot) broomstick w/ a grounded hook on the end
used to "Crowbar" high voltage capacitors in high power vacuum tube installa-
tions such as AM radio stations and "Shaker Tables" (as are "over the hill"
behind Bldg 38).  AKA a "Crowbar".

+Idiot Stick.  A railroad switchman's tool consisting of a 4 foot broomstick
w/ a wire hook on the end.  Used to align the links in Link & Pin Couplers
(now displaced by an automatic design invented by a long forgotten black
man). Never really practical, hence the name, this tool served better as a
weapon. Many a Hobo has been "Hit with an Idiot Stick."

>IEEE.  Institute of Electrical and Electronic Engineers.  A professional
organization of engineers by and for managers.  Significant primarily for the
technical forums sponsored and the standards produced by its Technical Com-
mittees.

>IEEE-488.  A slightly modified version of the HP-IB system designed by
Hewlett-Packard.  Also called the "General Purpose Interface Bus" (GPIB).
Used primarily to interface test equipment, particularly bench top gear.

>IEEE-696.  AKA S-100 Bus AKA Altair Bus.  An updated version of the 100 pin
bus structure popularized by the MITS Altair computer.  Originated because
MITS got a good price on 100 pin edge card connectors.  Claimed to be a
standard sufficiently exhaustive as to allow multivendor systems on a plug in
and go basis.  Some problems.  Remarkably successful.

>IEEE-802.X.  A group of LAN standards.  802.3 is CSMA/CD superset of Ether-
net, w/ both Baseband and Broadband versions.  802.4 is Token Bus ala MAP.
802.5 is a Token Ring.  The initial squabbling, sponsored in part by IBM, has
settled down, but much remains to be done.

>IGES.  Initial Graphics Exchange System.  An all ASCII (Verbose) format for
the interchange of CAD information.  With over 135 element types (at last
count)and hundreds of options, IGES transfers are anything but transparent
(Labels get lost a lot).  No one implements the entire element/option set so
100% transfers between unlike systems are rare.  ANSI Y14.26 M-1987 (V 3.0)
is identical to NBSIR 86-3359, April 1986.

>Incremental Compiler.  A compiler that preserves the line by line nature of
the original source code so that patches can be made by recompiling only the
changed lines.

>Information Hiding.  A method of top-down modular programming which "hides"
hardware/process specific details from the upper "Management" levels.  Always
more code and overhead (read lower performance) than optimal, this scheme
tends to restrict platform dependencies to a few simple modules, an advantage
in porting to new iron.  Widely used commercially, which is why Posix (which
replaces those "few" modules with "sockets") ports are so easy.

>Inode.  Internal Node (Number).  The slot Number in a Disk's Catalog File
containing the location, size, date of creation/update and any attributes
(such as access permissions) associated with a data file.  Notice the File's
Name is missing.  Names are kept in data files called "Directories" which
are created, manipulated and altered by Users.  Users do not have access to
the Inode File.

  When you create a File, the Name you specify is "linked" to an Inode which,
in effect, is the "Real" name of the File.  When you ERASE a File, the
Name/Inode linkage is broken.  When Inodes are "Orphaned" (have no links)
their disk blocks are placed in the Free List and they become available for
Reuse.

  DOS allows only a single "link" per Inode.  Unix, VMS, RSX and many other
Systems allow multiple links (called "aliases").  On Ginger "Mail", "email"
and "mailx" all point to the same file and are functionally equivalent.

  Some programs ("ls" on Unix for one) react to the name you used to call
them.  "ls", "lsx" and "lsf" all produce DIR listings using the "ls" program,
but "lsx" and "lsf" act as if you had set the "/X" or "/F" switch, respec-
tively.  DOS shows signs of heading that way, too, as Version 3.X passes the
program's name as argv[0] (for "C" Users), something not very useful unless
multiple links are allowed.

>Instruction Set.  The collection of binary tokens that make up the list of
legal commands for a particular processor (CPU).  During execution, these
tokens are expanded into microcode (usually a sequence of such words) that
control the various gates, registers, etc. to do something useful.  In gener-
al, the larger the token, the more options allowed, i.e., the "richer" the
instruction set.

>Interface.  The boundary between two entities.  A fence across which is
passed information and control signals.  May be hardware or software.

>Interlaced.  A scanning scheme popularized by TV to minimize flicker by
repainting the CRT in two passes interleaving odd and even lines.  Superior
for the display of motion, interlaced systems are poorly suited for computer
displays due to "frame jitter" and are rarely used for serious work.

>Interleave Factor.  A number which determines the order in which sectors on
a mass storage medium are accessed.  It can be optimized to make data re-
trieval more efficient.

>Interoperability.  The ability to network machines of varying origin, con-
figuration and vintage so that they work together as expected.  Possible
"Real Soon Now".  (Single Vendor Solutions don't count).

>Interrupt.  An event demanding immediate attention, like a doorbell or a
telephone ringing.  A process which responds to an external stimulus is said
to be "interrupt driven".

>Interpreter.  A portion of the operating system that creates object code one
line at a time from source code just prior to execution.  There is no object
file.  Easy to change and debug.  Fast edit cycles.  Supports TRACE opera-
tions.  Slow to execute.  BASIC is usually interpretive.  See also "Parser".

>I/O.  Input/Output.  Moving information into and out of the CPU.

>I/O Redirection.  A mechanism provided by the DOS/Unix shells for changing
the source of data for standard input and/or the destination of data for
standard output and standard error.  See Pipes.

>ISDN.  Integrated Services Digital Network.  A Telco digital/digital voice
network underwhelming in all aspects except cost.  Currently (1988) being
test-marketed in Atlanta.  By-Pass technologies such as VSAT (Very Small
Aperture Terminals for Satellites), fiber optics, point-to-point microwave
and even Sytek on Cable TV are keeping the cap on Telco's greed.

>ISO.  International Standards Organization.  A world-wide standards body.
ANSI is the USA representative.  Recently noted for the GPIB standard and the
Open Systems Interconnect model (See same) which ended the IBM Antitrust
suit.

>ISO Network.  A suite of protocols ala TCP/IP.  Based at the lower levels
(OSI layers 3 & 4) on the protocols which Xerox published following the
failure of X-TEN.  Mail (X.400) barrows heavily from the (unpublished) Xerox
"Courier" protocol from XNS resulting in a dynamite package.  FTAM handles
file transfers and VTP handles virtual terminal access.  Of these three
application level protocols, only X.400 is being delivered (June 88).  FTAM
is "Real Soon Now" and VTP is vaporware.  NBS has been mandated by Congress
to assist in the transition of Government Users (primarily DOD) to ISO.
Considering the TCP/IP installed base, a successful port of X.400, FTAM and
VTP could set up another RS-449/RS-232 situation.

>IRM.  Information Resource Management.  The new "Buzz" for ADP.

   Computer Scientists, by virtue of IBM's creation of the field and
continuing support, are the mouthpiece of the Mainframe Mindset.  So long and
so loud have they blasted their particular brand of bovine dust that the
Public in general (and Congress in particular) believes their's is the only
valid viewpoint.  As a result, knee-jerk jerks have saddled everyone with
regulations that demand Risk & Threat studies for Pocket Calculators,
consideration of Halgon Fire Suppression for Laptops and lenghty studies (in
triplicate) for LaserJet printers (lest we compete w/ NAVPUBs).

   It isn't that Congress doesn't know we, the Users, exist.  They don't even
Suspect.  Not a Clue.

                                    -J-

>JAN.  Joint Army/Navy.  A designator indicating the part so marked has met
rigid standards for fabrication and performance.

>Jargon.  The technical terminology of a particular group.  AKA "Computerese"
The familiarity with which is popularly termed "Computer Literacy".

>JCL.  Job Control Language.  The crude beginnings of an operating system in
the days of Batch processing.  Job control allows users to selectively stop
(suspend) the execution of processes and continue (resume) their execution at
a later point, to move processes into background and to set (or reset) execu-
tion priority.

>Johnson Code.  An unweighed BCD code easily generated w/ a shift register
recirculated through an inverter.  Once popularly used in electronic coun-
ters, now found primarily in digital wristwatches.  AKA Shift-Counter Code.

>Joy Stick.  A small, erect lever resembling the control stick of an air-
plane.  Used as a cursor control scheme.  Popularized by video games.

                                    -K-

>K.  Usually 10^3 (1,000).  When discussing data, 2^10 (1024).  Thus, 64K is
really 65,536 bits.  In the same vein, a memory "Meg" is KxK (1,048,576).

>Kermit.  A Public Domain file transfer program/protocol created by Frank da
Cruz of Columbia University.  The character-oriented protocol is prized for
its ability to work with all kinds of hardware/software/ops systems from
micros to Crays and the solid EDAC scheme that tolerates noisy phone lines.
The Kermit program is surprisingly sophisticated including such features as
"Sliding Windows" for Satellite Shots and on-the-fly data compression.

  "Kermit" is a marvelous name derived from old Celtic meaning "Free from the
Restraints of Society" with the implications of wandering like a gypsy.
("Hermits" shun society and stay put).  "Kermit, the Frog" is a Jim Henderson
muppet true to the tradition.  Likewise, the da Cruz's creation honors the
tradition, but he confesses that it's name was taken from a Muppet poster.
"Kermit" is a muppet trademark and is used by permission.

>Kernel.  The operating system executable code responsible for managing the
computer's resources, such as allocating memory, creating processes, and
scheduling programs for execution.  Loaded at Bootup, the Kernel stays RAM
resident at all times.  ISRs (Interrupt Service Routines), device drivers and
the like comprise most of the Kernel code.  Generally invisible to Users,
Programmers access the Kernel via "System Calls".  Much of SVID is the func-
tional spec for the Unix Kernel.

>Keypunch.  Originally, a machine designed to punch rectangular holes in a
pasteboard card.  Now, the act of entering information into a computer via a
keyboard.

+Kilroy.  A civilian employee of the Brooklyn Navy Yard, Kilroy was a welding
inspector assigned to Liberty (cargo) Ship production during WW II.  Since he
worked Graveyard shift, his crews rarely saw him although his chalk marks
outlined rework for the day shift.  Acceptance sign-off included a small
reminder that a nosy bald little man was Overseeing their work.  Finding
that, the welders packed up and moved on leaving the pipefitters and mechan-
ics to  pounder the source of this moonlight graffiti.  Soon    ___
Kilroy began to find his little man chalked on all sorts of    /_ _ \
tanks, bombs and war goods.  The French underground adopt-    | o o ~|
ed him as a means of taunting the Nazis, who left us   ---uuu----U-----uuu---
a thick file on an Allied Agent who signed his Work:     Kilroy Was Here.

>Kludge.  A jury-rigged lash-up that works.  Both a slam and a left-handed
compliment to German General von Kludge who, in the days following D-Day,
fought a brilliant delaying campaign w/ a rag-tag collection of old-timers
and boys using available resources, often in unusual and innovative ways.

                                    -L-

>LAN.  Local Area Network.  A network serving the data communications needs
of a limited area.  The larger LANs are classified as "MetroNets" and cover a
50 mile radius.  The trade off is throughput vs distance so very short sys-
tems can have very high data exchange rates (EtherNet uses 10Mbaud) while
MetroNets usually run about 135Kbaud/channel (as does CenterNET locally).

>LASAR.  Logic Automatic Stimulus And Response.  Originated on Navy contract,
D-2 LASAR was first marketed by DigiTest as D-4 LASAR which became a defacto
standard for logic simulators.  Based on Bell Labs "D" algorithm (A-C didn't
work), LASAR handles circuits as NAND gate equivalents using the "D" madmouse
in a maze method to discover the test vectors required.  DigiTest was pur-
chased by Teradyne who moved LASAR to a VAX-11/780 calling it D5 LASAR.
LASAR version 6 drops the "D" mouse, which has become less effective in
dealing with modern bus- oriented circuits.  Powerful.  Expensive to use.
More expensive not to.

>LASER.  Light Amplification by Stimulated Emission of Radiation.  A light
source produced by "quantum pumping" the electrons of a gaseous, liquid or
solid media into an elevated energy state.  Electrons drop from this excited
state to an intermediate level, giving up a photon of light in the process.
On dropping into the lowest energy state (giving up a photon of heat), the
electron is "pumped" back to the highest state by an external energy input
usually light or current flow.  By using mirrors, light rays are bounced
through the media encouraging transitions to the intermediate state.  In so
doing, the light ray is "amplified" into a very strong beam of phase coherent
light having a very narrow beam width and virtually no beam spread.

>LASER Printer.  Basically a Xerox machine in which the image is either drawn
on the drum in the manner of a super speed pen plotter or scanned on as a
high density TV image (or a combination of both) using a (usually) gas LASER
as a light source.  Very expensive due to the optics used.  Produces a "copy"
for an original.  Very fast (tens of pages per minute continuously).

>Learn.  In digital functional testing, the creation of Test Vectors (See
Same) by capturing responses from a known good "Gold Standard" device running
on an ATE system under stimulus from stimulus vectors.  Frequently used in
testing ROMs, this technique produces valid results IF these conditions are
met:

  1. The device does not Race.
  2. The stimulus vectors adequately exercise the device.
  3. The "known good" device actually is (a non-trivial problem).

>Letter Quality.  Said of printed material.  The highest quality indication
used for typed/printed text.  The defacto standard is the IBM Selectric using
a carbon ribbon.  Generally considered to be at least 1200x1200 dpi equiva-
lent.

>LIFO.  Last in/First Out.  A stack.

>Light Pen.  A stylus containing a photodiode.  As the electron beam writing
on a CRT passes by, an interrupt is generated.  From this indication the
system can determine the location on the CRT to which the Light Pen is point-
ing.  Used as a cursor control scheme.  Never popular due to the need to
cover the area of interest with the photo detector.

>Line Printer.  A printer that lays text on paper a line at a time.  Implies
speed.

>Linear.  Said of circuits or devices.  Analog (as opposed to digital).

>LISP.  LISt Processing language.  A product of John McCarthy's work in the
middle 60's on non-numeric languages.  Particularly well suited to symbol
manipulation, tree searchable, problem solving and (especially) list process-
ing. Used almost exclusively by the Artificial Intelligence (AI) community.
Developed at MIT.  Arithmetic operations are handled in RPN.  Some experts
predict LISP will absorb and displace FORTH as memory size becomes less of a
system constraint.

>Little Language.  The Command Set for a Tools that is, in effect, a Special
Purpose programming language.  Examples are GW-Basic's DRAW command and "awk"
under Unix.

>Local Variables.  Variable names that are independent from all other varia-
bles of the same name in different program segments.  Implies that the varia-
ble table is created as the program segment is entered and collapsed on
leaving, i.e., the variables "forget" previous values.  Improperly implement-
ed in Pascal.  'C' does it right and also provides a "static" local variable
that retains its value between function calls.

>LOGO.  A teaching language for children.  Features heavy graphics with a
"Turtle".  Some versions use "Sprite" graphics, icons that can be moved as a
single unit.

>Look-and-Feel.  Probably the worst can of Worms the US Patent Office set
loose in the 1980's.  Apple Patented the "Look & Feel" of the MacIntosh GUI,
suing MicroSoft, IBM and others for Icon infringement.  The 1990's opens w/
Apple being sued by Xerox whose Ill-Fated "Star" system (developed at Palo
Alto Research Center (PARC)) originated Icon GUIs, Mice & Smalltalk.  At the
very least Apple's Patent Should be Invalid due to Prior Art, even if they
did Steal it Fair & Square.

>LPM.  Lines per minute.

>LRC.  Longitudinal Redundancy Check.  A scheme for detection of bit errors
in a block of transmitted or recorded data based on a vertical parity check,
i.e., the Least Significant Bit (LSB) of the LRC byte is the parity bit for
all LSBs in the block and so forth to the Most Significant Bit (MSB).  This
scheme is normally combined w/ a byte-wise parity check so that the data
block is stitched together both horizontally and vertically w/ parity checks,
making an undetected bit error unlikely.  AKA Vertical Redundancy Check
(VRC).

>LSB.  Least Significant Bit.

>LU6.2.  An IBM "Peer-Equal" SNA protocol which nearly became an ISO standard
(until somebody noticed it requires at least one Mainframe node).  Avoid.

>LUN.  Logical Unit Number.  A Fortran construct that allows peripherals or
files to be assigned at RUN time.

                                    -M-

>Macro.  A prefix meaning "Long" or "Large".  Also, an assembly language
subsection specified to the assembler by name.  A like feature of certain
Compilers (notably 'C').

>Mainframe.  Originally, a large computer of the type installed in classical
computer centers.  Now any computer mounted in an equipment rack and accessed
via terminals.  Implies speed, although the performance available to any one
user may be disappointing.

+Mainframes, History of.  The era of Mainframe Computers as the dominant
digital technology has spanned 4 decades of continuous evolution.  The
beginning is marked w/ the sale of UNIVAC I (1950) and the end w/ IBM's
10,000 Job Roll-Back in Mainframe Production divisions (about 5% of its US
Workforce) at the close of 1989.

Dates are fuzzy except where specific announcements make sharp breakpoints:

  Decade Zero (1940-1949) ---> Homebrew.  Birth.
    1940  ABC demonstrated. (News Photos published 15 Jan 40).
    1943  ENIAC begun.
          "Z-Machine" (a General Purpose CPU) Proposed to German War Staff.
    1944  Colossis I in Use by England's Project Ultra "Code-Crackers".
          Harvard Mark I Completed.
    1945  von Neumann Proposes to Store Programs in RAM, a Radical Concept.
    1946  ENIAC & Bell Labs Relay Calculator Completed.
    1948  IBM's Ultimate Calculator (SSEC) on display in Manhattan.
          Cambridge EDSAC, First Stored Program (von Neumann) CPU.
    1949  MIT invents Magnetic Core RAM (using a Pill Mold).

  Decade One (1950-1959) ---> Vacuum Tubes.  Infancy.
    1950  First commercially sold mainframe.  (UNIVAC I).
    1952  Mnemonic Assembly Language (IBM 650).
    1953  First Commercial "Parallel" CPU, IBM 701 w/ Williams Tube RAM.
    1954  Texas Instruments Invents the Silicon Junction Transistor
    1955  Magnetic Core RAM on IBM 705.  (Total of 19 Built).
          Survey Reports 88 Mainframes in Use in US.
    1956  Fortran I (First HLL) Operational (on IBM 704)
    1957  Flying Head Disk (5 Mb) on IBM 305 w/ RAMAC DOS
    1958  Texas Instruments/Fairchild Invent the IC.
          Survey Reports 103 Mainframes in Use in US.
    1959  IBM Controls 90% of the Mainframe Market.
          Switch-Over to Solid State Begins (Late 1959).

  Decade Two (1960-1969) --> Transistors.  The World Discovers Computers.
    1961  Time Share Introduced w/ DEC's PDP-1
          DOD develops COBOL-61 (and IBM popularizes it).
          Survey Reports 222 Mainframes in Use in US.
   c1962  Virtual Memory DOS.
    1963  ASCII Published by ANSI
          Total US ADP/ADPE Market tops $1,000,000,000.
    1964  IBM System 360 Establishes Upward Compatible Hardware/Software.
          DEC introduces the PDP-8 and coins the term "Minicomputer"
          ENIAC/Univac Basic CPU Patents Granted.  Honeywell Sues.
          Survey Reports 334 Mainframes in Use in US.
   c1965  DTL Logic replaces discrete transistors.
          Finite Element Analysis Developed (First CAD).
    1965  Brooks Act mandates ADPE Oversight for US Government CPUs.
   c1966  Operating Systems standard on all Mainframes
    1969  Cache RAM.
          BiSync Introduced.
          Justice Dept. Begins IBM AntiTrust Suit.
          IBM Controls 90% of the Mainframe Market.

  Decade Three (1970-1979) --> ICs.  Mainframes Change the World.
    1971  1 Kb DRAM.
          IBM releases TSO (Time Share Option) for S-360/370 Family.
   c1971  TTL SSI Begins to Displace DTL.
   c1972  ECL ICs Appear in CPU/ALU Sections.
    1973  System Network Architecture (SNA) Announced.
          ENIAC/Univac CPU Patents Declared Invalid.
          Winchester Disk Drive (14 Inch) Technology.
   c1973  TTL MSI Phase-in Starts.
    1974  INTEL 8080 Marks Start of MOS LSI.
    1975  US Buyers Spent 78% of Their Computer Budgets on Mainframes.
    1976  DEC VAX-11/780 Super-Minicomputer.
    1978  CRAY-1 Super Computer.
   c1979  USSR abandons Trinary Technology, Seeks Western Binary Machines.

  Decade Four (1980-1989) --> Open Systems.  The World Changes.
    1981  IBM PC Announced.
    1982  SNA Commits to Full ISO Open System Interconnect Compatibility.
          IBM AntiTrust Suit Folds.
          IBM Controls 70% of the Mainframe Market.
    1985  IBM switches focus from Batch to Transaction Processing.
    1986  SVID published.  Unix begins to gain momentum.
          IBM Starts "Trimming" its Workforce.  (Except Mainframe Divisions).
    1987  EC Forces IBM to Publish Internal Standards.
          CRAY Research switches to Unix.  Ditto Data General.
          X-Windows from MIT for Unix.
    1988  Sperry-Univac combines w/ Burroughs to form UniSys.
          DEC fails Posix & loses $4.3 Billion Open System Mini Bid.
          US Buyers Spent Only 35% of Their Computer Budgets on Mainframes.
    1989  DEC buys MIPS, HP buys Apollo.
          DEC promises full ISO/Posix/GOSIP compliance.
          IBM, Amdahl labor to port AIX (Unix) to large Mainframes.
          IBM trims 10,000 jobs from Mainframe Manufacturing, a first.
          IBM Controls 70% of the Mainframe Market, 60% of which is Export.

  Decade Five (1990-1999) --> Connectivity.  The World Changes Mainframes.
    1990  IBM's 3390 Disk Introduced (First Micro to Mainframe Migration).

---> Update 89:  As this Decade draws to a close, the Era of Dominate Main-
frames has clearly passed.  We have witnessed a technology born in the
1940's grow thru adolescence into middle age.

  Computer Literacy, once reserved for the "Learned Few", is now taught in
Grade Schools.  The Mainframe CPU of the Middle 60's now resides on desktops,
operates on NiCads & totes home in a shoulder bag.

  Or to put it another way, if Automobiles had Kept Pace w/ Computers, Your
Next New Car would Cost About $5.00, get a Quarter Million Miles to the
Gallon & be Garaged in a Shoe Box.  When WAL-MART stocks Floppies and
B.Dalton Booksellers peddle Software, You Know the Mystic is Gone.

  Mainframes are not dead.  They will survive as DBMS Engines, Compute Nodes
and Payroll/Inventory Platforms.  They have become, like the railroads,
haulers of "heavy freight"; still vital, but not a mainstream technology.

>Manchester Coding.  A digital signaling technique used to simulate an analog
signal with a data stream.  Used by IEEE-802.3 BaseBand LANs (Ethernet).

+Mark I.  The Harvard Mark I Computing Engine.  Begun in 1936 as an elec-
tromechanical implementation of Babbage's Analytical Engine by Howard Aiken.
Funded by a Million dollar grant from IBM, design started in 1937 w/ con-
struction beginning in 1939.  Taken over by the US Navy during WWII, it was
much altered in the rush to produce immediate results for BURORD (now
NAVSEA). About 51 feet in length, containing some 12,000 telephone style
signal relays and controlling a total of 78 mechanical calculators, the Mark
I ended up being called an "Automatic Sequence Controlled Calculator" (ASCC).
Completed in 1944.  Programmed via plug boards and fed data via TTY punched
tape, ASCC's throughput was about 3 FLOPS.  Altogether, four versions of the
basic design were built, but only the first is significant as its success was
soon over-shadowed by the much faster ENIAC.  The ASCC represents the apex of
electromechanical computer design which, while not reaching the fullest
measure of Babbage's dream, did much to establish the validity of the binary
approach he proposed.

>MCA.  MicroChannel Architecture.  IBM's Proprietary 32-Bit, 20 Mhz Bus
scheme for its PS/2 PCs.  Specifically designed to be incompatible w/
previous PC/XT/AT boards (the PC-AT bus became very popular as the "ISA"
Industry Standard Architecture), MCA "features" a much smaller form factor
and less than half the available power of ISA boards making use of surface
mounted devices and ASICs nearly manitory.  This, plus the distributed
control scheme used complicates Reverse Engineering thereby inhibiting
"clones".

   IBM really expected MCA to become an instant hit, so much so that its
licensing requirements include a "royalty" penalty for previously produced PC
clones.  Underwhelmed by the response and pressed by the "Gang of Nine" who
developed the half again faster (and fully backward compatible) EISA Bus, IBM
waived the "penalty" to certain vendors, amoung them NCR and Tandy.  However,
even the purchase of a full license does not unlock PS/2's "Chastity Belt".
MCA intimately interacts w/ IBM still closely guarded ROM BIOS making full
compatibility nearly impossible, as Iomega, Tandy, NCR, Hayes and even OS/2
co-conspirator Intel have painfully discovered (May 90).  Avoid.

>Metacharacters.  "Wild Cards."  Characters that have special meaning to the
operating system.  These are generally "transformed" (hence the "meta" han-
dle) by character expansion, matching, etc.  Strictly "FM" (Flash Magic),
meta- characters speed tasks (and blunders).  Unix probably has the richest
set of such critters, actually several sets including those used by the Shell
and "Regular Expressions" used fully or in part by the various Tools.
Strictly speaking, DOS has none (the "*" and "?" are passed unchanged), but
various languages (and most Tools) simulate Command Line Expansion ala Unix
giving DOS a limited functional equivalent.

>MIB.  Multi-Interconnect Board.  A fancy name for a multilayer PC board.
Also, MLB.

>Micro Code.  Originally, machine language.  Strictly speaking, the coding in
which the instruction set of a processor (CPU) is written, i.e., the "true"
machine language of the CPU.  Sometimes used to describe assembly language
object code.  More correctly applied to the coding used in Writable Control
Store CPU's.

+Microcomputer, History of.  Indirectly, the HP-35 Pocket Calculator (the
first "electronic sliderule") sparked the microcomputer revolution.  In the
scramble to bring out competing models, a Japanese firm named 'Busicom'
approached INTEL with a multichip design they wanted reduced to three chips,
a ROM, a RAM and a processor.

  Although the product itself was dropped, INTEL marketed the processor chip
as the 4004 in 1971, a modest success that found its way into most of the
bank time/temperature signs of the era.  Almost immediately, an 8 bit ver-
sion, the 8008 was brought out.  It wound up in traffic light controllers and
many other tasks, but users pointed out limitations in the design which,
after all, was still pretty much a calculator chip.

  INTEL brought forth the 8080 (the first fully featured microprocessor) in
1974.  The "Experts" predicted a total lifecycle run of about 10,000 chips,
not enough to break even. (The 8080 was in production more than a decade w/
no estimate on the number produced worldwide (including in the USSR)).

  Meanwhile, HP was successfully exploiting its calculator technology in the
9800 series desktop machines (introduced in 1971) and DEC was planning a
small machine later marketed as the LSI-11.  The MITS Altair was the first
commercially successful machine based on the 8080 (introduced in 1974, MITS
had 10,000 units installed by 1976).

  While hardware hackers tried to master the S-100 bus, Commodore carefully
prepared a move into the home computer market with their "PET" (Personal
Electronic Translator), a machine that looks very much like a baby HP-9845,
which they showed around in the Spring of 1977.  While they were doing market
research and shopping for financing, Tandy decided to poach with the TRS-80.

  Intended as a quick in/grab/out move, 2,000 units were built in the first
run of which it was hoped that 1,800 could be sold by Christmas (1977) given
a multimedia blitz of hard sell advertising.  That carefully planned blitz
got derailed in midflight as the middle of the second week found Tandy sold
out and back ordered to the tune of some 50,000 units.  Deciding to stay in
the  market, Tandy built a modern facility in Ft. Wayne, Indiana, which is
still in production.

  The PET came (and went) and Tandy chose to coast instead of exploiting its
commanding initial lead (at one point more TRS-80's had been sold than all
other computers ever built from Day One combined).  Apple IIs came in Summer
1977 and (facing tough Tandy) evolved an "Open System" approach featuring
drop-in third party upgrades and software.

  The Explosion of Microcomputer Technology was Fueled by a Pent Up Passion
for Computer Use that Mainframes (even Minis) couldn't (or wouldn't) fill.
It was more than a "Revolution", it was a Revolt:

  Decade One (1971 - 1979) ---> "Silicon Valley" hatches a RAM Scam.
    1971  Intel 4004/8008 Microprocessors Introduced.
          IBM Introduces 1 Kb DRAM.
    1973  IBM Introduces the "Floppy Disk" (8" SDSS 3740 Format).
    1974  Intel 8080 MicroProcessor.
          Altair 8800 Microcomputer w/ S-100 Bus.
    1975  BYTE, first microcomputer magazine.
          "Kansas City" Cassette Standard allows Software Publishing.
          CP/M Introduced.
    1976  5.25" Floppy Drive Introduced.
          HP-9845A "Qwert" Introduced.
          Apple I Kits built in Steve Job's Garage.
          Bill Gates Founds MicroSoft.
          Altair has an Installed Base of 10,000 Units.
    1977  Apple II Introduced.
          Tandy sells 52,000 TRS-80s within 10 days of Introduction.
    1978  Apple DOS.
          TRS-80 Model II w/ MicroSoft Basic in ROM.
    1979  VisiCalc (First Spreadsheet) on Apple II.
          8" Winchesters Introduced.
          Osborne I "Totable" CP/M Portable.
          More TRS-80's Built & Sold than All Others CPUs to Date.

  Decade Two (1980 - 1989) ---> The Gathering Swarm.
    1980  Shugart 5.25" Hard Drive w/ (future) SCSI Interface
    1981  IBM PC (8088 w/ CGA Graphics).
          Osborne Folds.  CP/M Fades.
    1982  DEC Rainbow (a Closed System) Sails & Fails.
          Apple III (100% DOA Closed System) Fails.
    1983  Phoenix Technology "Cracks" IBM's Copyrighted ROM BIOS.
          Clone Wars begin.
          IBM PCjr "Peanut" Bombs Big.
          PC-XT w/ 8086 & 5 Mb Hard Drive Introduced.
          One New Microcomputer Introduced for Each Business Day this Year.
    1984  MacIntosh introduces Apple's GUI.
    1985  PC-AT w/ 286  & EGA Graphics.
          Clone Wars Peak.
    1986  Grid Introduces the "Laptop" Computer.
          MS-Windows GUI Released.
    1987  PS/2 w/ VGA Graphics & MCA Bus. (A "Closed" System)
          Intel 386 Microprocessor.
    1988  IBM introduces OS/2, the last significant Closed OS.
          386 Laptops w/ VGA LCDs & 100 Mb Hard Drives.
    1989  PS/2 486 Introduced.
          Open System EISA-386 PCs Appear.
          OS/2 "Presentation Manager" GUI Released.

  Decade Three (1990 - 2000) ---> Micros Go Mainstream.
    1990  IBM's 3390 Disk Introduced (First Micro to Mainframe Migration).
          MS-Windows 3.0 ships.  First widely accepted PC GUI.

  In the beginning, there were Hackers and they begat Micros, actually just
High Tech Toys.  VisiCalc was the first Really Significant Thing Micros did
that Mainframes didn't.  Business Users began to buy Micros, which caused IBM
to join in.  This encouraged Users to invest in hardware & software creating
Market Energy that reached Critical Mass in the Middle 1980's.  Mainframe
Power on Desktops migrated Mainframe jobs away from Data Processing Centers.
And an odd thing happened: The Cutting Edge passed from Mainframes to Micros.

  As Mainframes end their era on Domination, Micros begin theirs.  LANs,
Connectivity, Applications Portability and Information Mobility move Center
Stage as these are the concerns of Micro Users, i.e., these are the Issues of
the 90's.

>Microprober.  An analytical tool used in the failure analysis of
microcircuits which physically "probes" the surface of the (delidded) chip
using finely sharpened wires so as to measure voltages/signals and exercise
portions of the chip's circuitry.  Now almost obsolete due to decreasing
feature size of chip topography.  As one user termed it: "It's getting to be
like trying to stab a matchbook cover with a telephone pole on the end of a
crane."

>Mid-Split.  Said of LANs.  A broadband technique in which the radio spectrum
available on the coaxial cable is split into two bands separated by a blank
space in the "middle" of the bandwidth, usually centered on the commercial
FM/TV band which is often "piggy-backed" down the coax system.  The low band
is used by modems at the user's port to transmit outbound traffic.  These
signals are collected, amplified, band-shifted, and rebroadcast by the sys-
tem's "Headend" unit onto the upper band.

>Minicomputer.  A term coined (1964) to describe the DEC PDP-8 computer,
which became the defacto standard for small machines right down to the flash-
ing lights and row of switches along the front panel bottom.  A "mini" is
smaller than a Mainframe, larger than a "micro" and pretty near impossible to
define.

>MIPS.  Million Instructions/Second.  A Crude measure of CPU power.  With the
advent of RISC machines, MIPS has become a Buzz word of the first magnitude
(A normal (CISC) instruction often encompasses several RISC state- ments).
An attempt to "Clarify" the situation by referencing "VAX-780" MIPS (a common
practice w/ DEC) has been further complicated by the fact that the VAX-780 is
not (as commonly accepted) a 1 MIPS machine.  Tests by IBM (and others) place
its performance at about 0.47 "Real" MIPS, whatever that means.

>MIS.  Management Information System.  See DBMS.

>Modem.  Modulator/Demodulator. A box that converts a digital bit stream to
analog tones for transmission.

>Modular Programming.  A style in which subsections of the programs are
compart- mentalized into distinct units ("Modules") with defined interfaces.
Superior for test and debug.  May result in additional overhead, especially a
profusion of flags.  Generally a good idea as it assists Software Mainte-
nance. See Also Context Switching.

>MODULA-2.  A second language by N.Wirst, the author of Pascal, which is more
complete and better thought out.  Originally intended to be a new class of
hardware/software combination running on a machine specifically optimized for
its highly modular design (and so demonstrated c1982). Impressive in that
form, Modula-2 has dropped most of its innovative enhancements in order to
serve as a transportable general purpose language.  As currently marketed
(1984) Modula-2 is basically an "Extended" Pascal.

>Monti Carlo.  An analysis technique applied to situations too complex to be
solved using generalized mathematical methods.  A numerical analysis approach
in which a random number generator drives a model to produce a spectrum of
specific solutions which, taken as a whole, profile the response of the
complex system.

>MOS.  Metal-Oxide Semiconductor.  The tap-root technology of the microcom-
puter revolution.  Based on Insulated Gate Field-Effect Transistors (IGFETs),
MOS comes in two "flavors", P-Channel (PMOS) and N-Channel (NMOS).  PMOS has
been almost totally replaced by NMOS as it is inherently faster.  A low
power/high impedance technology, MOS is subject to static (ESD) charge dam-
age.  Special handling/shipping precautions are required.  See Also CMOS.

>Motherboard.  The main PCB into which other boards/assemblies plug.

>Mount.  Originally, the physical swapping of 9-Track mag tapes, the process
disk users generally call ""loading".  After spinning up the disk, the oper-
ating system is informed of its presence by executing a "Mount".  Once
"Mounted", the new disk is a transparent part of the directory tree until it
is "UnMounted", spun down and removed.  Failure to "UnMount" before removal
can fatally damage the removable disk, the directory system it was mounted
into or both.

>Mouse.  A hand held pointing device used as a joy stick replacement.  A
current fad.  Effective, but requires an uncluttered space close to the CRT,
a luxury.

>MSB.  Most Significant Bit.

>MS-DOS.  MicroSoft Disk Operating System.  A defacto standard for 80x86
family Microcomputers.  Originally marketed in August 1980 by Seattle Comput-
ers as 'QDOS' ("Quick & Dirty" Operating System) as a temporary operating
system  for their new computer until CP/M-86 became available. (Called "Q&D"
because  it was a minimal CP/M Knock-Off representing only 2 manmonths of
effort).  Sold to MicroSoft in July 1981 where it was adapted to the IBM PC
(IBM calls it  'PC-DOS').  Later versions (3.x notably) have become very
Unix-like featuring  I/O Redirection and "Pipes".

>Multi-Drop.  A Polled Master/Slave scheme in which multiple terminals-
minals share a common channel, twist pair or Coax.  The effect is that of a
mux due to the Master/Slave environment (terminals listen or speak only when
addressed).  Implies block mode (usually line at a time) transmission.  Slow.

>Multi-Layer.  Said of Printed Circuit boards.  A composite board built up of
thin layers of insulation alternating with patterns of metallic conductors.
Expensive.  Allows high density circuitry.  Difficult to repair. Intercon-
nects between layers remain a problem area.

>Multi-Tasking.  The ability to run more than one application program at a
time.  Essentially a time share concept, except that only one user is in-
volved.

>Multi-Wire.  A small run technology competitive with Multi-Layer.  A general
purpose PCB is customized by small wires routed and welded in place by a
computer controlled machine.  An insulating coating is applied to fix the
wires in place for handling.  Said to provide the flexibility of Wire Wrap
(See Same) and the compactness of Multi-Layer with better circuit character-
istic than either.

>MUMPS.  Massachusetts General Hospital Utility MultiProgramming System.  A
general purpose interactive language developed in the 1960's.  MUMPS contains
a powerful set of string handling constructs, a pattern matching facility and
timing functions, all of which support highly interactive (conversational)
programs.  Designed for time shared minicomputers, MUMPS is more an operating
environment than a language.  Among the features of this environment is a
hierarchical data base shared among users via file transparent commands. ANSI
standard XII.1-1977.

>Mux.  A multiplexer. A device to support more than one channel on a communi-
ca- tions path.  May use time slicing (digital information) <"Time Division
Multiplexing"> or Frequency division multiplexing (analog information), a
technique which divides the path's available bandwidth into slots rather like
is done in broadcast radio and TV.

                                    -N-

>N.  A prefix indicating an inverted output.

>NAND.  A logic gate implementing the Boolean 'AND' function followed by an
inversion (a 'NOT' function).  The basic digital logic primitive from which
all others can be created.  The "Gate" referenced when discussing circuit
size in terms of "Equivalent Gate Count".

>Nanosecond.  The time required for light to travel from the top of this page
to the bottom.  A pulse on a wire will travel roughly the width of this page.

>Native Code.  Machine executable binary specific to the CPU under discus-
sion.

>NBS.  National Bureau of Standards.  Former name of NIST.

>NCC.  Numerical Control Code.  AKA EIA Code.  An 8 bit alphanumeric code
used in punched tapes for numerically controlled manufacturing machines
(tools). Popular because, unlike ASCII, the tape reads the same whether
loaded correctly or upside down (reversing the tape reader results in correct
text), a positive feature when dealing with unskilled users.  Used by the
TI-553 ATE.

>Near Real Time.  The ability of a system to respond to monitored conditions
fast enough to control the monitored process. Example: Automotive computers.

>Negative Resistance.  A region on the conduction curve of certain devices in
which the current flow decreases as voltage increases.  Neon lamps, tunnel
diodes, magnetic amplifiers and other "parametric" amplifiers (MASERs, etc)
can have a region of negative resistance.  Such devices can be used as ampli-
fiers, oscillators, bistable switches or memory elements.  Normal amplifiers
operated under high positive feedback likewise display negative resistance,
i.e., they will oscillate.

>New-Line.  An End-of-Line marker.  By tradition, a LineFeed (called by both
Unix and DOS "\n").  DOS, being a spin-off of CP/M uses the CR-LF combination
in its text files (making them directly printable).  If a file is opened in
"Text" mode (the default), CR-LF couplets are converted to "NewLine" markers
automatically.

>Nibble.  Also Nybble.  A group of 4 bits. Half a byte.

>Nine Track Tape.  A magnetic tape format popular in 800 bpi and 1600 bpi
densities.  Characters are printed across the tape width-wise.  Resembles
punched paper tape except that a 9th bit has been added (for parity).  A GCR
(Group Coded Recording) technique extends 9-Track to 6250 bpi, but the Read-
After-Write capability is lost making automatic skip-over of bad areas and
tolerance of dirty or damaged media impossible, hence the need to "certify"
6250 bpi tapes.

>NIST.  National Institute of Standards and Technology.  The new Handle for
the old NBS (National Bureau of Standards).

>NLQ.  Near Letter Quality.  Said of printed material.  See Letter Quality.

>No-Break.  Said of power sources.  Capable of switching from commercial
power to an alternate source (batteries, generators, etc.) without loss of
the power waveform.  See UPS.

>Noise Floor.  The level at which a signal's identity becomes masked by
noise. Viewed on a Spectrum Analyzer, system noise appears as a band of
random noise spikes ("grass") along the lower edge of the display.  The
average upper edge of this region is termed the "Noise Floor" for a system
and represents the smallest measurable signal (See Dynamic Range).

>NonVolatile.  Said of digital memory media.  Does not "forget" when power
removed.  Examples: Disks, Tape, Bubbles.

>NRZ.  Non-Return to Zero.  A coding method used on some data tape recorders.
Pulses in alternate directions signify successive ones while no pulse signi-
fies a zero bit.  An NRZ pulse train has a 'DC' component making it unsuit-
able for many applications. NRZ is the default coding for 800 bpi 9-Track
Tapes.

>NTSC.  National Television Standards Committee [Standard].  "Normal" (US)
Color TV signals.  Basically a black & white image into which color subcarri-
er sidebands have been interleaved.  A "color burst" on the "back porch" of
the blanking signal synchronizes the receiver allowing recovery of the color
information.  Invented by RCA.

>Null Modem.  Under RS-232 it is assumed that devices will connect to a
modem, not directly to each other.  A pair of modem connectors cross-wired to
simulate two back to back modems.

                                    -O-

>Object Code.  The collection of binary numbers produced by a compiler oper-
ating on a source code file.  The native language of the machines.  Also
called "machine language".

>Object-Oriented Graphics.  Graphical images made up from "special charac-
ters" (dot patterns) that are handled and printed like normal text.  A quick
and dirty scheme to get game graphics.  Popular with small machines and often
call "Sprites".

>OOL.  Object-Oriented Language.  Any of several languages (notably C++ and
Smalltalk) that allow grouping of data into named "Records" or "Structures"
that can have additional "handles" (called "Attributes") by which they can be
sorted, manipulated and selected.

+OOL, What's a.  Consider the Object-Oriented Language (OOL) named "Dry
Goods" that runs on the platform "SuperMarket."  Your mission, if you choose
to accept it, is to select a single member of the data type "Chicken Noodle"
of the Class "Soup."  The data type "Chicken Noodle" contains three data
elements ("Broth", "Noodles" and (by some reports) "Chicken"), but we won't
get into that.

  We know that the item we seek has a label affixed to it on which are listed
a number of "Attributes" including the vendor's name, "Campbell's."  We also
know that it has "Inherited" the Attribute of the generic SubClass, "Canned
Goods", which tells us we can skip bagged and boxed items such as Potatoes
Chips and Corn Flakes.

  The Stockboys have arranged merchandise according to label Attributes,
placing "Fruit Juices" and "Vegetables" in different areas than the Class we
seek ("Soup") even though they haven't actually sampled the contents (data
elements) in any of the "Objects" on the shelf.  OOLs let you do that.

  Once we have found the Class "Soup", we still have to sort on label At-
tributes to isolate the SubClass "Chicken", which includes "Chicken Gumbo",
"Chunky Chicken" and "Chicken Noodle."  The concept of "Classes" and "Sub-
Classes" in OOLs is a bit messy as to which is which (kind of depends on your
viewpoint).

  It gets worse.  Consider that the "Instant Soup" SubClass contains the data
type "Chicken Noodle" w/ the same three data elements inside ("Broth has the
value, "Dried") which also belongs to the Class "Soup."  The "Instant Soup"
SubClass isn't a member of the SubClass "Canned Goods" (it is in the SubClass
"Boxed").  OOL Class/SubClass breakdowns tend to be a "Top-Down" arrangement,
but exceptions are allowed.

 A sort on "Noodles" and "Campbell's" gets us to the correct location on the
shelf and we can select one of the data objects of type "Chicken Noodle"
(preferably one without the Attribute "Dent").

  To Recap, OOLs fix "Attribute Labels" to data structures.  These may be
used in sorting, grouping and selecting processes.  In addition, data struc-
tures may "Inherit" implied Attributes from Class/SubClass(s) they are mem-
bers of.  Class/SubClass links are usually (but not always) layered like
Directories.

  OOLs also associate Attributes w/ processes operators ("Methods").  For
example, the Method "CAN-OPENER" operates on the SubClass "Canned Goods" but
not on the SubClass "Boxes."

  Methods don't have implied (inherited) Attributes like data objects, but
they can have "Virtual Functions" (which makes them "Polymorphic").  For
example, the Method "OPEN_CAN" assumes the function of "CAN-OPENER" with the
SubClass "Soup", the function "CHURCH-KEY" with "Fruit Juice" and "POP-TOP"
with "Canned Soda."  In other words, it alters its operation (Method) based
on the Attributes of the data object being processed.

>OCR.  Optical Character Reader.  The logical inverse of a printer.  Takes
text and makes a data stream.  Physically resembles a small office copier.
Becoming popular in office automation.

>Octal.  A scheme for representing all combinations of 3 bits by the numbers
0-7.  Also, a radix 8 number system.  Favored by DEC. Weird to use.

>Octet.  Officially defined as a collection of 8 bits by the standards making
bodies.  (The term "byte" is actually ambiguous.  See Same).

>OEM.  Original Equipment Manufacturer.  A vendor who purchases parts and
subassemblies and manufactures a system.  An OEM may volume purchase periph-
erals (usually at a discount) and remarket them under his own logo.  An OEM
who works at the "Box" level is called a "System's Integrator."

>OpAmp.  Operational Amplifier.  A linear amplifier having a very high open
loop gain intended to be run under high (99% or greater) negative feedback.
Used in filters, integrators and many other analog circuits including analog
computers.

>Open System.  Any Computer Operating System meeting these criteria:

   1. The System adheres to well-defined specifications which are available
      to all comers at little (or no) cost.
   2. The above Specification is actively supported by several independent
      competing vendors.
   3. The above Specification/Standards are not controlled by a single (or
      small group of) companies.
   4. The above Specification/Standards are Hardware independent.
                                             Source: UnixWorld 11/89 pg 192.

>Open Systems Interconnect Model.  A theoretical ideal description of a seven
layer "cake" which, if everyone plays and no-one cheats, will allow anyone to
interface to and communicate with anyone else.  Perhaps overly complex, it is
a good, honest try:

     ---- Layer ---               --- Function Performed ---         examples
  7. Applications layer ---> User's Program (Pac Man or Whatever).   Kermit
  6. Presentation layer ---> The "System" as the User Sees It.     POSIX/GOSIP
  5. Session layer --------> Log-on/Log-off and Passwords.
  4. Transport layer ------> Packetizing/Addressing, encryption & File Systems
  3. Network layer --------> Routing and CRC checking/ARQ servicing.   DECnet
  2. Data Link layer ------> Flow control and Handshaking.          X-ON/X-OFF
  1. Physical layer -------> Interface to a metallic or fiber path.    RS-232C

Pushed by the International Standards Organization, IEEE, ANSI and Uncle Sam.

>Operating System.  The "Chain of Command" for a computer system.

>Optical Disk.  A mass storage technology based on "burns" made on a disk
shaped media using a strong light source, usually a LASER, and read off
optically. Usually packaged to emulate a magnetic flying head disk subsystem.
Super high storage capacity, but usually a write-once situation (erasable
units have been demonstrated).  Media is relatively inexpensive and physical-
ly rugged, although some forms deteriorate w/ age.  Useful for archival
storage and bulk data transport.

>OS/2.  The Single User, Multi-Tasking Operating System of the IBM PS/2.
Features an icon driven "Presentation Manager" ala Mac (Apple sued), multi-
tasking and networking.  Comparable in size to Xenix (which tests 13+ times
faster), OS/2 is fat, slow, and late.

  Generally considered a failure as a stand-alone system, MicroSoft and IBM
are betting heavily on networking in IBM's office automation scheme (featuring
a central mainframe, naturally).  The failure of MS-Windows, which early
gained the reputation as a disk-blaster, is directly traceable to OS/2
(MicroSoft emulated a PS/2 in MS-Windows and did it badly).

  OS/2 might have succeeded had VGA's memory access been better.  As it is,
DOS applications running under OS/2 suffer a 3-1 speed penalty during screen
access, something clearly visible (and annoying) to Users.  Alternatives such
as DESQview offer better performance at lower cost.  AIX, Xenix and other
Unix ports offer more features, tools and networking alternatives.

  Realistically, OS/2 must be viewed as an attempt to recapture the business
PC user, IBM's traditional focus.  While IBM has committed AIX to full Posix/
Gosip compliance, OS/2 is (and apparently will remain) a "closed" system.
Avoid.

---> Update May 90: MicroSoft Announces the Next Release OS/2 will be Posix
Compliant w/ GOSIP to Follow.

---> Update August 91: IBM & MicroSoft split (IBM owns OS/2 outright now).
The above Release has been renamed "MS-Windows NT" (New Technology) and
remains Vaporware.  Meanwhile, IBM & Apple made up and plan a jointly
developed Operating System for PS/2.  Where does that leave OS/2 Users?  IBM
says, "Trust Me!".  Avoid.

>OSI.  See Open Systems Interconnect Model.

>Originate/Answer.  Said of modems.  A designation reflecting the frequency
assignments of the send and receive tones.

>Overhead.  The difference between the potential throughput of a system and
the actual throughput.

>Overlay.  A (usually plastic) "Cheat-Sheet" for a Key Pad that fits over or
around application defined keys.  Also, a technique for memory management.
See paging.

                                    -P-

>Packet.  A collection of data bits enclosed in one or more framing flags.
Conceptually equivalent to an envelope.  It has an address, usually a return
address, and a CRC tag to detect damage.  The "letter" is the data bytes that
comprise the message.  Used by Kermit, X-Modem, X.25, EtherNet, TCP/IP,
DECNet and Sytek Boxes.

>PAD.  Packet Assembler/Disassembler. A protocol converter for an X.25 port
on a Public Data Network (PDN).

>Pad.  In telecommunications.  A level dropping network (may be fixed or
variable) used to adjust signal levels.  Implies impedance matching.  Adjust-
able pads may be named after the form of the network used, e.g., "T-Pads" or
"L-Pads".

>Padding.  The inclusion of null characters in a text stream to allow mechan-
ical printers time to perform line feeds and carriage returns.

>Page Fault.  The name of the Interrupt generated by a Memory Manager when
information needed is not RAM resident.  See Virtual Memory, Operation of.

>Paging.  Also called "overlaying".  A method of fitting a large program into
a small memory space by segmenting the program and controlling the loading so
that the system believes the program is held completely in memory.

>PAL.  Said of TV signals.  Phase-encoded Alternate Line. A color TV system
popular in Europe and Japan.

>Parasitic.  A "Stray Effect" that (maybe) can be influenced, but not con-
trolled.  A hardware problem.  Software Parasitic are called "Antics".

>Parity.  The property of being either odd or even.  Specifically the tally
of the "1" bits in a byte is either odd or even.  Forced by setting or clear-
ing a bit (the 8th bit in ASCII).  Less effective when noise bursts can span
several bits, Parity checking is only 60% effective at 1200 baud and is now
little used in telecommunications.

>Parse.  Literally "to cut".  A process popularized by BASIC (HP first and
then Microsoft) in which the user's input source text is ripped apart, syntax
checked and then converted to Tokens for storage.  Basically, this is the
first pass of a two pass translator.

>PASCAL.  A highly hyped language created in 1971 by N.Wirst as an alterna-
tive to ALGOL-60, a language widely used to teach 'Structured Programming'
concepts. Designed as a teaching aid, Pascal early gained many advanced
concepts such as Modular Programming constructs and portability via Transla-
tor/Pseudo-Code techniques.  (The intermediate 'p-Code' was said to be the
native code of the "Ideal Pascal Engine", apparently to justify calling the
Translator a "Compiler".  See Also 'Systems, Evolution of').  In demonstrat-
ing compiler design/optimization, Pascal revived the labor intensive scheme
of manually inserted cues used by ALGOL-60.  Widely taught as a 'Pseudo-
Language' (See Same), an application for which it is well suited.  As origi-
nally released, Pascal lacked many elementary concepts necessary for practi-
cal use.  For example, it did not implement the "Mathematical Hierarchy" of
operators (algebraic equations did not give expected results) and had virtu-
ally no I/O structure.  This led to a host of "Extensions" negating one of
Pascal's strongest selling points, portability.  These "Growing Pains" re-
flect that the language was not well thought out as a general purpose tool
ala Fortran. (See Also Modula-2).  The influence of Pascal on Fortran-77 and
BASIC-87 is clearly evident.  Professional enthusiasm for Pascal cooled
somewhat when staffing requirements proved 6-8 times greater than for Fortran
IV (Itself a difficult language).  AKA ANSI/IEEE-770X3.97-1983

---> Update 90: Turbo Pascal is leading a wave of Renewed Interest in the
Language as an Object-Oriented Language (OOL) alternative to C++.

+Pascal, Blaze.  A French mathematician (1623-1662) notable as the inventor
of the first mechanical adding machine (1641).  Pascal's brilliant career
spanned 14 years, ending abruptly in 1654 w/ a "Religious Experience" which
drove him into seclusion and obscurity.  The rapid rise and sudden decline of
Pascal curiously parallels that of the language named in his honor 3 cen-
turies later.

>PC.  Personal Computer.  A workstation used by a single user.  By popular
usage, the IBM PC/XT/AT (80x86) family (including clones) running MS-DOS.

>PCB.  Printed Circuit Board.  Also: PC board.

>PCM.  Pulse Code Modulation.  A digital technique for time division multi-
plexing.  Used by T-1 CXR systems.

>p-Code.  PseudoCode.  An intermediate between source code and executable
machine language which may either be interpreted or compiled to native code.

+PDP-X.  Programmable Data Processor.  The backbone of Digital Equipment
Corporation (DEC) since the introduction of the PDP-1 in 1961.  Modestly
successful through several models until the solidly successful PDP-8, the
machine for which the term 'Minicomputer' was coined.  A 12 bit machine
originally offered w/ 1.5 Kb of magnetic core, paper tape reader/punch and a
slick open reel magnetic tape drive (1 inch tape).  Adopted enthusiastically
by scientific users and ATE OEMs, the PDP-8 became the engine of many diverse
systems, including the one that filmed the space battle for STAR WARS.  So
much a defacto standard that early microcomputers copied the blinking lights
and row of switches on the front panel, the PDP-8 evolved into the PDP-11
series in 1971.  The PDP-11 standardized on the 16 bit word which allowed it
to directly address 64 Kb of RAM (as opposed to 4 Kb on the PDP-8).  Using a
two bit extension, the PDP-11 hardware memory manager handles up to 256 Kb of
RAM arranged in 64 Kb pages.  The lower 8 Kb of RAM is fenced off into a
"Monitor" (Kernel) area, with the lowest 512 bytes being specifically re-
served for pointers (See Pointer Driven).  The upper 8 Kb of each page is
mapped to the UNIBUS, an asynchronous extensible bus that allows the computer
to be intimately involved with peripheral devices, a real advantage to ATE
OEMs who make great use of this capability.  This leaves the user 56 Kb of
space to work in (48 Kb in the lowest page, which the 3270 uses as Fore-
ground/BG0).  The hidden 8 Kb of RAM at the upper edge of each page is re-
served for system use (buffers, pointers, scratch area, etc.).  The powerful
handshaking scheme of the UNIBUS provides both the largest measure of the
system's power as an ATE engine and the primary limitation to its speed
(throughput).  By modern standards, the PDP-11 series is very slow (0.2
MIPS).  An examination of the Motorola 68000 microprocessor shows that is was
specifically designed to facilitate the migration of applications from PDP-11
systems, a tribute to the success of the series.

>Peripheral.  Said of computer devices.  Not part of the main system.  Usual-
ly in a standalone box.  Implies that the system can function without the
device.

>Pick.  An operating system which is quietly doing for business users what
Unix is doing for technical users.  Includes a Relational Data Base (See Same
). Created by David Pick, this system is (as of 1988) used by 80% of the
business computer users in Europe.  The Pick OS had an installed base of
100,000 systems worldwide by 1986, 40% of which were on PCs.

>PILOT.  Programmed Inquiry Learning Or Teaching.  A language created at
University of California (San Francisco) for Computer-Aided Instruction (CAI)
users (teachers, primarily) who needed to develop/test CAI dialogue programs
w/o becoming computer programming experts.  First of its kind.

>Pink Poly.  A (pink) plastic used to prevent the build up of static charges
on ESD sensitive devices (such as CMOS) during storage and handling.  While
Pink Poly will bleed off accumulating static voltage, it can not protect
against an ESD Zap from an outside source (such as an ungrounded hand).  A
variation using a sandwich around a metallic inner layer can provide such
protection, but is more expensive and less widely used.

>PIP.  Peripheral Interface Program.  A name coined by DEC for a collection
of file handling utilities callable from RSX.  Includes the capability to
copy, rename, delete, etc. files on mass storage.  Also, a CP/M utility of
similar function.

>Pipe.  A method of redirecting the output text stream of one program into
the input port of another.  DOS, which is not multitasking, uses scratch
files which are created/collapsed transparently.  Unix uses I/O buffers,
firing up/suspending program execution as they fill and empty.  By tradition,
the "Pipe" symbol is a vertical bar <|>.

>Pipeline.  A hardware technique to  increase the throughput of a CPU by
anticipating the next instruction to be executed and fetching it from main
memory to a queue in high speed local memory.

>Pixel.  Picture Element.  The smallest addressable portion of an image. A
dot.

>PL/1.  Also PL/I.  A structured language written by IBM (released 1965) as
an effort to combine the best features of Fortran IV, ALGOL-60 and COBOL.
Hobbled early by unreliable compilers, PL/1 failed to displace other estab-
lished languages, primarily due to its  complex syntax.  Widely taught but
little used, PL/I has a small, avid following ala APL.  A variation, PL/C was
written at Cornell University.

>PLOT-10.  A Graphics Defacto Standard set down by Tektronix for the 4010
Bistable Storage Tube terminals.  Based on a universe 1024 by 780 pixels with
the origin in the upper left corner.  Being replaced by GKS.

>Pointer.  An address that literally "points" to something of interest.

>Pointer Driven.  Said of operating systems.  A style of operation based on a
set of pointers, usually located in the first 512 byte "page" of core (so
called "Low Core").  The location of these pointers is fixed and will not
change from software revision to revision.  The pointers themselves, however,
may change value in order to point at "Dispatch Tables" (lists of secondary
pointers) or interrupt service routines which are located elsewhere.  A
powerful technique.  Nearly all modern operating systems use at least some
ariation of the idea which significantly improves maintainability by allow-
ing the option to slide, expand, delete or relocate tables and routines
without impacting the overall system.

>Poll.  A "Sound-Off" prompt from the Master in a Master/Slave situation.

>Port.  A place where information enters or leaves a system.  An interface.

>Posix.  An IEEE evolving standard describing the interface between an appli-
ca- tion program and the operating system (machine) on which it runs.  The
intent is to establish a "3-Point Hitch" for software.  As with farm imple-
ments, the standard hitch will allow your "New Holland" bale-stacker to
attach to your John Deere tractor, draw power from it and be controlled by
it, even though one is painted bright red and the other Lincoln green (those
OEMs don't much like each other, either).  A good idea.  Possible.  Probably
Practical. AKA IEEE-1003.1-1988  AKA FIPS 151.  See also: SVID.

>Postscript.  A Printer Language popularized by AppleTalk laser printers.
Claimed to be a Page Description Language, Postscript is actually a Font
Language that is little more than FORTH macros.  Effective for fonts and
simple graphics, Postscript's performance is dismal elsewhere.  For example,
a pixel dump of an AutoCAD drawing formatted by PageMaker (a Desktop Publish-
ing defacto standard page layout utility) that normally prints in 2 minutes,
40 seconds as straight dot patterns requires over 32 minutes under Post-
script. (Source: BYTE 8/88 pg. 172).

>POTS.  Plain Old Telephone Service.  A Telco Term.

>Printed Circuit.  Originally, a circuit silk screened onto an insulating
base using metallic (usually silver) paint.  Later, a copper clad phenolic
board taped with a "resist" tape and etched to remove excess (untaped) areas.
This technique is still used by hobbyists.  Generally, a circuit board made
by exposing a copper clad fiberglass ("epoxy") board which has been coated
with a "photoresist" to a negative of the desired circuit layout.  After
developing, the unexposed areas are etched away chemically.  Holes for compo-
nent mounting are drilled and the entire circuit board is tin plated in
preparation for soldering.  May be followed by a plating process to deposit
gold on connector fingers or to "plate through" interconnect holes, especial-
ly in double sided or multilayer boards.  With the advent of automatic board
stuffers and wave soldering machines, PCBs have become the standard construc-
tion format for digital equipment.

>Process Control.  The use of computers in closed loop mode to monitor and
regulate some (usually chemical or mechanical) process.  Implies Near Real
Time Response.  Example: Automobile Engine Computers.

>Program.  A sequence of instructions to the computer in some form (binary or
text) that, ultimately, winds up as executable binary that causes the machine
to do something (hopefully) useful.

>PROM.  See EPROM.

>Prompt.  Character(s) output to the CRT to indicate completion of a Command
Cycle and that the system is ready for another command.  Usually a dollar
sign <$> ("Sharp" <#> Unix Super-Users).  Controlled by "Environment" varia-
bles, Prompts are User selectable (set PS1 & PS2 for Unix or PROMPT for DOS).

---> An Historical Note:  The traditional "$" prompt came from IBM's use of
that symbol on JCL cards to signal the system to print those on the opera-
tor's console when the job deck (of punched cards) was loaded.  The operator
then manually adjusted the CPU as required.  Later, JCL cards routed to the
system "Monitor", the administration program that evolved into the Kernel.
As CRTs displaced punched cards, the Kernel prompted users to enter JCL
commands by starting the line with the (then) familiar "$" symbol, signifying
the system was ready for another JCL command.

>Proportional Spacing.  A printing technique first found in office use via
the IBM Executive Typewriter.  Under this scheme, the width of the character
cell varies with the character printed so that the finished text looks very
Professional".  Often done in software and frequently combined with right
margin justification (so called "micro justification").  Publishers use a
variation based on letter groups called "Kernning", a techniques that im-
proves the appearance but complicates OCR recognition.

>Protocol.  A game plan to control the flow of data over an information link.
May use shifts in voltage levels on physical wires (handshake).  May involve
the exchange of "reserved" characters (Character-Oriented Protocols).  May
involve the exchange of "flag patterns" (Bit-Oriented Protocols).

>Protocol Converter.  A "black box" that interconnects two devices (or data
links) that play by different game plans (protocols).

>PS/2.  A "Less Than Successful" IBM product line notable primarily as a
MilePost in the History of Computers.  PS/2 was IBM Corporate's vision of how
the PC market should be (incompatible hardware/software, no upgrade path and
no third party competition).  It also marks IBM's first serious failure at
establishing a defacto standard.  IBM rushed the PS/2 to market two years
before its operating system was available (OS/2 remains largely Vaporware),
a common practice in Mainframes.

  A modest machine at best, PS/2 is a slow, costly "closed" system in an era
of fast, inexpensive "open" systems.  Hobbled by dismal VGA Graphics Mode
performance, PS/2's flashy GUI is unacceptably slow.  EISA PC-AT "Super-
Clones" consistently deliver better "Bang/Buck" w/ PC-AT board compatibility
and multi-vendor after-market upgrades.

  Stung by loss of PC market share, IBM specifically designed PS/2 to be
incompatible w/ existing PC products.  Expecting that OS/2's VGA GUI and
MCA's superior bus thoroughput would generate instant demand, IBM imposed  a
crushing licensing requirement: Payment of Royalties on all PC products
previously produced.  The response was UnderWhelming.  At least they
achieved one Objective: There are No Clones.

>Pseudo.  A Prefix meaning "False" or "Not what it seems", but in the
positive sense.  (More there than meets the eye).  See Also Quasi.

   Consider this legend of the Old West:  The Wells-Fargo Overland Stage was
the only link between far-flung mining settlements, cow towns and outposts
before the Rails came in the late 1880's.  Hands down champion of all Stage
drivers was a short, heavy-set teamster named John Smith.  Fearless in storm,
Indian attack, prairrie fire or hold-up, the Wells-Fargo Museum proudly
displays letters from passengers who owe their lives to Smith.  The famous
outlaw, Sugarfoot, fell to Smith's shotgun blast.  As the Old West faded,
Smith retired to the Black Hill's last rowdy boomtowm, Deadwood.  Remembered
as the toughest man ever to handle a six horse rig, Smith's origin, identity
and reasons for seeking the rigors of frontier life remain unknown.  She is
buried in the Odd Fellows Cemetery at Deadwood, having been a member in good
standing for many years.
                    (Source: Old Farmer's Almanac)

>Pseudo-Code.  An intermediate language used to assist program design prior
to coding into the target language.  Pascal is an excellent Pseudo-Code
language, which is why it gained such wide recognition before conversion into
an actual computer language.  AKA Program Design Language.

>Pseudo Random.  Said of signals, numbers or bit patterns.  Apparently ran-
dom, but actually predictable once the generating algorithm (the "key") and
the starting point (the "seed") are known.

>PSK.  Phase Shift Keyed.  Data is transmitted as shifts in the phase of a
single tone.  Phase shifts produce a burst of sideband frequencies which can
be detected and used to set/reset a flip-flop to recover the original data
stream. More sensitive to noise than FSK.  Used in high speed modems such as
the Bell 212A types (1200 baud).

>Public Domain.  A legal term meaning the item in question can be accessed,
copied and used by anyone without payment under the Copyright Law.  Congress
has placed the copyrights for all Government publications (including soft-
ware) in the Public Domain.  Individuals may likewise do so by including the
phase, "Copyrighted to the Public Domain" in their publication.  Generally,
the author specifies a limited transfer of rights as in the case of Kermit
which states that the program can not be sold for profit and must include the
Copyright Notice.

>Public Key System.  A class of link encryption schemes based on the property
of certain mathematical operations which are readily computed forward but
nearly impossible to reverse.  Under this concept, two keys are used, one
which is handed out ("Public") and the other which is held in private.
Information to be sent is encrypted using the public key.  Only the holder of
the private key can decrypt the information.  Superior to the DES (See same)
method.

>Punched Tape.  A paper or mylar ribbon into which are punched holes in
patterns that, when read across the width of the tape, represent alphanumeric
characters. ASCII is the most common code used.  Baudot code (5 levels) is
still used for some TTY work.  The NCC or EIA code is used for numerically
controlled machines like the TI-553 ATE.  Punched tape may be read either
mechanically using pins or via a photo-optical reader, the latter requiring
"Chad" tape (the holes being fully punched out).  Until standards evolved for
magnetic tape, punched tape was the preferred media of exchange for programs
and data with nearly all minicomputers including at least a tape reader.
Many early ATE machines were either driven from punched tape or punched out
their readings on punched tape (for later printing on a TTY machine).  For
many years, it was common practice to boot up computers from punched tape.
Pity those who forgot the magic sequence of instructions to get the tape to
load (or who lost their boot tape to a carnivorous reader).

>Pushdown stack.  See "stack".

>Push/Pop.  The process of placing ("pushing") or removing  ("popping") a
piece of information to/from a stack.  Includes updating the stack pointer.

                                    -Q-

>QAM.  Quadrature Amplitude Modulation.  A scheme to encode 3 bits/baud by
combining 4 state Phase Shift Keyed (PSK) w/ 2 state Amplitude Modulation
(AM) to produce 8 distinct signaling states.  Since the two modulators inter-
act, some states are less easily detected, a problem if S/N deteriorates.
Some implementations (See V.32) skip those states accepting a 5:1 bit/baud
ratio (instead of 8:1) gaining noise tolerance in the trade.

>Quadrature Shift Keyed.  A PSK technique with 4 distinct states.  Allows
doubling up of data bits so that bps is twice the signaling rate (baud rate).

>Queue.  A waiting line.  Service is on a first in, first served basis. A
LIFO.

>QWERTY.  The first 6 keys of a standard typewriter keyboard layout. Invented
by Christopher Sholes as part of the first practical typewriter (1868), a
design using gravity-return keys which were prone to jam if operated too
fast.  His innovative solution was the QWERTY layout. Specifically designed
to slow a typist doing business typing, this layout dominates while others of
demonstrated superiority (most notedly the Dvorak layout) are ignored.  The
53 ASCII keyset is now considered the defacto standard compliment of keys
while the IBM Selectric is the defacto standard for key size, shape and
placement.

>Quasi.  A prefix meaning "False", with the connotation of being "Less than
meets the eye" with the implication that this falsehood will be exposed in
time, e.g., the Quasi-Stable state of a One-Shot.

   Consider this Tale of the Old West:  South of Albuquerque, New Mexico,
is a well watered area of wooded hills, farms and ranches that figured in a
bitter range war, the "Lincoln County War", that spawned the legend of "Billy,
The Kid" who (it is said) killed 20 men before his 21st birthday.  Sheriff
Pat Garrant's posse tracked Billy to a farm house where a gunfight occured.
The hasty midnight burial that followed contrasts sharply with the more usual
display of vanquished shootists (as was done at Northfield, Mn) leading to
rumors that the wrong man was killed.  However, the reward was collected and
"The Kid" was never again seen in New Mexico.  In 1989, a petition was  filed
in Texas seeking the posthumous pardon of "Brushy Bill" Williams (who died in
1963) under the amenesty that settled the Lincoln County War citing his
invovlement in that conflict as "William (Billy, The Kid) Bounty".
                                (Source: Unsolved Mysteries, an NBC-TV Series)

                               -R-

>Race.  An undesirable (hopefully) temporary oscillation in a digital device
that results in an unpredictable output state.  Generally caused by timing
problems in hardware.  Test vectors must be padded w/ extra steps to avoid
causing races (i.e., be "de-raced") otherwise the vector set is worthless.
One of LASAR's great strengths is its ability to flag (and remove) race
conditions from generated test vectors.

>Radix.  The base of a number system.  The value of the multiplier applied to
the 'Tens' position in '10'.  In common numbers, the base is ten.  Binary
(base 2), Octal (base 8) and Hexadecimal (base 16) are also popular.

>Radix-50.  An alphanumeric bit compression scheme originated by DEC to
reduce the storage requirements of file names, etc.  The letters 'A-Z' are
assigned sequential bit values in a 4 bit nybble starting at value one.
Value 27 is assigned to '$' and value 28 is assigned to '.' <dot>.  Values
30-39 are assigned to the digits '0-9'.  Since the nybbles range in value
from 0-39 (zero is a space), three of them can be packed into a 16 bit word
by offsetting the leading nybble by 1600 and the second nybble by 40, then
summing the three nybbles, i.e., the nybbles are treated as if they belonged
to a Base 40 number system.  DEC refers to this as 'Radix-50 Packing' since
the value '40' in common (base 10) numbers is '50' in the Octal number sys-
tem.

>Rails.  Also Power Rails.  Viewed on a free triggering scope, a digital
pulse train resembles a railroad track viewed from the air.  The "rails" are
the static high and static low (Vcc and ground) levels of the signal.  By
extension, "Power Rails" are the Vcc and Ground distribution busses.

>RAM.  Random Access Memory.  By tradition, the main read/write memory of a
computer.

+RAM, History of.  Throughout the history of calculators, tabulators and
computers, the limiting factor to performance has always been memory.  Bab-
bage designed mechanical RAM much too intricate to be fabricated in his time
(tabulators and adding machines came close).  Mark I and ENIAC used relays as
RAM.  ABC demonstrated a refreshed capacitive drum memory.  EDVAC, UNIVAC I
and other "Serial" computers of that era used acoustic delay lines (mercury-
filled steel tubes were popular) for main RAM.  The first IBM computer (the
model 650) used a magnetic drum.  The first IBM mainframe used the "Williams
Tube", an electrostatic true random access memory built in England.  RCA
never got their version to fly.  The first really successful RAM spun out of
the MIT "Whirlwind" project: Ferrite Core RAM.  Slow, bulky and expensive by
today's standards, Core RAM put computers reliably to work.  Semiconductor
RAM started to make inroads as "Scratchpad" RAM and fast cache for disks long
before IBM invented MOS DRAM in 1971.  There is a rumor to the effect that
microprocessors began as a dodge to sell more RAM chips (probably not all
that untrue).  The explosive growth of microcomputers, MOS RAM and microproc-
essors is certainly interrelated.  DRAM has maintained an astounding four-
fold capacity increase every three years for almost two decades.  Static RAM
isn't far behind.

>RATFOR.  Rational Fortran.  A popular pre-compiler for Fortran which pro-
vides features not supported in Fortran itself and patches for some of For-
tran's more serious faults.  Written by Brian Kernighan (1975).  Another
popular pre-compiler is WATFOR (or WATFIVE).

>Read After Write.  A technique that verifies that information written to
memory, tape or disk exactly matches the data driving the writing process by
performing a read process and comparing the result to the original data.
Widely used on 9-Track drives at 800/1600 bpi.  If a drive writes "Extended
Record Gaps", it is doing transparent Read-After-Write.

>Real Soon Now.  The fourth Great Lie.  The others are: "The Check is in the
Mail", "I'll respect you in the Morning" and "I'm from the Government,  I'm
here to Help you."  RSN is the delivery date for Vaporware.

>Real Time Clock.  A Time of Day clock not referenced to the CPU timing
source.

>Record.  The smallest addressable part of a Random Access File.  Also, the
smallest physical division of a file (called a "Physical Record").  See
Sector.

>Recursive.  Said of Subroutines.  The ability of code to call itself without
clashing variables or losing the way back.  Implies that a local environment
complete with pointer preservation and local variables is established when
the subroutine is CALLed.

>Recycle.  To power down a system and then power it back up.  Doing so clears
many kinds of "Hang Ups".

>REDUCE.  The background language of the Tektronix 3270 ATE.  As the name
implies, the vendor was thinking in terms of a data reduction language, not a
fully featured general purpose language (which it clearly is not).  Basically
TEKTEST w/o the Test Table constructs, REDUCE is loosely based on Fortran w/
some cosmetic changes.  String handling capability is simulated using integer
arrays as text buffers.  Several constructs such as the LOOP statement show a
middle ground between Fortran and BASIC.  Both REDUCE and TEKTEST mimic
Fortran's ability to call assembly language modules and pass parameters to
them.  Much of the patching to both languages is accomplished via this route.
REDUCE and TEKTEST both use a TRANslator to compile the source <EDT> files
into tokens <TST> for execution via an interpreter.  See Also TEKTEST and
related TEKTEST topics.

>ReEntrant.  Said of Subroutines.  The same code can be used simultaneously
by more than one program or program segment.  Example: SIN(X) is ReEntrant.

>Refresh.  The process of regenerating information in a dynamic system.  For
CRTs, that involves repainting the image.  For DRAMs, that involves reading
and rewriting the bit storage capacitors.

>Regular Expressions.  Unix allows its Tools to use a rich assortment of
"WildCards" (See MetaCharacters), particularly for pattern matching Tools
such as "fgrep" (which DOS calls "FIND").  These WildCards and the rules for
combining and using them have come to be known as "Regular Expressions". Some
Tools extend or vary these, but most abide by (more or less) one of the these
three "flavors": Full, Limited and Tagged, used by "awk", "grep" and "sed",
respectively.  Regular Expressions are also used by the Shell, providing much
of its "Magic".

>Relational.  Said of Data Bases.  A scheme handling stored information as a
large array (as opposed to a branching tree).  Neither the exact form nor the
method of recall are fixed, a distinct advantage.  Useful for small data
bases. Popular on microcomputers.  dBASE II is a defacto standard.

>Relay.  An Electo-mechanical device composed of a Coil, an Armature and one
or more pairs of contacts.  These electrically actuated switches were first
used to "Relay" telegraph signals from one circuit to another (hence the
name).  Very large Relays are called "Contactors" and are used to switch
heavy loads such as mulit-horse motors.  Tiny relays called "reed relays"
actuate w/ milliwatts of power to control signals in electronic gear.

  Prized for their high ON/OFF ratios (milliohms vs Megohms), mechanical
relays are found in ATE machine's "Analog Switch Matrix" and as signal and
power control switches.  "Hot Switching" signal relays can burn the gold
coating off contacts resulting in intermittent operation.

  Mercury-wetted relays are position sensitive, but renew their contacts via
capillary action from a pool of liquid mercury with each actuation.  Such
relays are used in Power Supplies and where contact bounce can not be  toler-
ated.

>Reload.  The process of restoring the computer to operation after a fatal
system crash.  Uses Backup Files.  Always involves the loss of information.

>Report Generators.  Originally, the output portion of a data base system.
Now extended to 'Report Generation Languages' which are useful for formatting
output from all manner of applications programs, thereby simplifying their
design and improving the user's control over the output obtained.

>Reverse Engineering.  The art of starting with a product and unraveling how
it was made.  May involve the production of documentation and other software
to support fabrication of replicas.  Reverse Engineering is not of itself
illegal, (nearly all manufacturers do it) but neither does it bypass the
copyright and patent laws.  A carbon copy of a competitor's product is an
invitation to a lengthy court battle, but the inclusion of a "significant"
improvement is usually an adequate defense.

>RGB.  Said of Video signals.  A scheme using separate cables for the Red,
Green and Blue video information.  Popular for high resolution monitors.

>RISC.  Reduced Instruction Set Computers.  A new class of machines based on
an IBM case study.  A misnomer.  Running counter to conventional wisdom that
the way to increase the "Power" of a computer is to "enrichen" its instruc-
tion set, (See Word Length), RISC computers use many more internal CPU regis-
ters (512 vs 16) to reduce the rate of data shuffling to/from RAM.  This
increased register complement requires more bits in each token to address (9
vs 4), hence the "Reduced Instruction Set" (fewer options).  Properly manipu-
lated, these extra registers can result in significant speed gains in certain
applications.

>RJE.  Remote Job Entry (Batch).

>Roll Out.  The process of off loading RAM to storage (originally tape stor-
age) to free up space for a higher priority task.

>Roll-Over.  Said of keyboards.  The ability to differentiate, decode and
store bursts of keystrokes.  Spoken of in terms of the number of keystrokes
which can be handled in a burst, usually '2-Key Rollover' or 'N-Key Roll-
over', the latter being best for fast typists ('N' is usually about 10, not
that that makes a practical difference).

>ROM.  Read-Only Memory.

>root.  The highest level of a hierarchical directory. so named because such
directories resemble branching trees.  Normally the base (root) directory has
no name and is designated by "/" (MS-DOS uses "\" to protect the guilty).
Also, on Unix systems, the Super-User (generally the system administrator) is
named "root" by default.

>RPN.  Reverse Polish Notation.  A scheme favored by HP for programmable
calculators.  Characterized by the entry of the data before specifying the
operation to be performed.  A bit weird to use.

>RS-232-C.  The most successful Electronics Standard ever.  Established by
the Electronics Industries Association (EIA).  Specifies signal levels and
pin-outs but does not specify the 25 pin Type "D" connector commonly associ-
ated with RS-232-C cables.  Now considered dated due to its unbalanced sig-
nals, wide voltage swings and limited distance (50 feet).  However, this is
still the most specified interface standard.  AKA X.20BIS.

---> Technical aspects of:

  An RS-232-C port is generally implemented using a 12V Swing around Ground.
Drivers source thru 300 ohms and receivers load w/ 1.5K.  That gives about
10ma of signal current and about 100mw of punch.  Being bipolar, the
waveshape is resistant to RC effects.  As can be seen, ample hysteresis and
noise margin were factored in:

-------------------- Must Withstant 25V Continuously ---------------------

 Five  Volts .............. Lowest Transmitted Space .....................
                                              2 Volts of Noise Margin Min.
 Three Volts -------------- Receiver Reports a Space ---------------------
                3 Volts
                Hysteresis                              <Dead Zone>
 ZERO Volts +++++++++++++++ GROUND (Data Ground) +++++++++++++++++++++++++
                3 Volts                                 <Dead Zone>
                Hysteresis
- Three Volts ------------- Receiver Reports a Mark ----------------------
                                              2 Volts of Noise Margin Min.
- Five  Volts ............. Lowest Transmitted Mark ......................

-------------------- Must Withstant -25V Continuously --------------------

  Designed to work w/ TTY machines and endure the hazards of the time,
any line can be connected to any line without harm; hacking is legal & safe.
RS-232's 50 foot limitation must have been an inside joke.  9600 baud links
running more than 3 miles on telephone twist pair are running on Center as
you read this (and have been for a decade).

   The choice of Negative True for Data Signals (others are Positive True)
reflects the TTY current loop practices of the time which used positive
ground, keying the negative line.  Other choices, especially the obscure
DTE/DCE notation, make RS-232 interconnections a high frustration experience.
Actually, a true RS-232 port (as some Mini's provide) is nearly worthless for
anything but a real modem.  (RS-232 is a modem standard).

   TTY used only 3 wires: Send, Receive and Data Ground.  Data Ground is
always Pin 7 (DB-25) or Pin 5 (DB-9).  The other two end up on Pins 2 & 3,
but which is which is seldom sure.  This is how it is SUPPOSED to be:

        DB-25 Pin               Signal Name             BD-9 Pin
           1            Shield Ground <if Any>
           2    !       Outgoing Data Signal               3
           3    ?       Incoming Data Signal               2
           4    !       RTS Flow Flag                      7
           5    ?       CTS Flow Flag                      8
           6    ?       DSR Are-You-There Flag             6
           7            Data Ground                        5
           8    ?       CXR Detect Flag                    1
           9            Reserved
           10           Reserved
           11           Printer Flow Flag (??)
           12           Secondary Channel DSR Flag
           13           Secondary CTS
           14           Secondary Channel Outflow
           15           Send Clock (Sync)
           16           Secondary Channel Inflow
           17           Receive Clock (Sync)
           18           UnAssigned
           19           Secondary RTS.  Ptr Flow Flag (??)
           20   !       DTR I-Am-Here Flag                 4
           21           CXR Strength Flag
           22   ?       My Phone is Ringing Flag           9
           23           Data Rate Selector
           24           External Clock (Sync)
           25           UnAssinged/Computer Busy Flag

   As I said, a Modem Standard.  Until approval of RS-232-D (out for vote
now), neither the DB-25 or DB-9 connectors are actually specified, though
tradition is strong.  Also in the -D revision is legalization of RTS/CTS
"Hardware Handshaking", a long popular -C violation.

---> Tips:

   Try 3 wire first.  Just connect the grounds & pins 2/3 so voltage appears
on both.  If nothing happens, loop pins 4-5 and 6-8-20 at each end.

   Nearly everyone sticks to the "Great Eight" signal lines (those w/ ! or ?)
except for printer OEMs who hide their flow control flags in odd places.  Get
the 3 wire rig to work first & then probe around watching for a flag output.
Don't forget RTS/CTS is popular (Pins 4-5 & 5-4 wired thru).

   Null Modems are: (2-3 3-2 4-5 5-4 6,8-20 20-6,8).  No Magic.

>RS-422.  A 5 volt balanced line standard for data circuits.  A good stand-
ard.  Good to 4,000 feet.

>RS-423.  A 5 volt unbalanced line standard intended to replace RS-232-C,
which uses 12 volts.  Not significantly better (except for the elimination of
two power supplies).  Response has been cool as RS-232-C remains hot.

>RS-449.  The least successful interface standard ever.  Supposed to replace
the RS-232-C standard, the public response has been underwhelming.  Primary
problem:  A 37 pin type "DB" connector AND a secondary 9 pin connector.  Too
many wires for too little gain.  Avoid.

>RTE.  Real-Time Environment. One "Pole" of Computer System orientation (DP &
ATE are the other two).  RTE encompasses data communications and other like
situations in which the focus is outward from the CPU.  Programs and control
structures are very simple to insure adequate speed in servicing
"interrupts". An RTE system does not have a "program flow"; it has a game
plan for responding to "tickles" from the outside world.  Internally elegant,
RTE systems are inherently User hostile, difficult to program and nondeter-
ministic (they are unpredictable).  A common misapplication is "Rack-N-Stack"
ATE where RTE produces great specs, high labor costs and dismal performance.

>Run-Time Module.  A small "Trailer Hitch" program (usually an interpreter)
that must be present at execution time.  Painful.

                                    -S-

>SAA.  IBM's new name for SNA.

>SAS.  Statistical-Analysis System.  A statistical language (and supporting
utility programs) developed at North Carolina State University in the late
1960's.  Made public in 1972, the language resembles PL/1.  SAS was specific
to IBM S370 mainframes until 1982 when a VAX-11/780 version was released.
Resembles APL in that it allows powerful array/file manipulations (in this
case statistical analysis functions) w/ compact notations.  Features an
internal "Standard" data format allowing ready transportation of data among
SAS programs, a distinct advantage.

>Scattergram.  A shotgun approach used on packet switch network to insure
vital traffic gets through.  The sender passes duplicate messages to all
attached nodes.  The receiver gathers in the wandering packets, reassembles
the message and discards duplicates.  Useful when messages are short but of
great value.  In current use by the Airline reservation industry.

>Scheduler.  Part of a multitasking (or multiuser) system's kernel, that part
which determines which tasks will run in what order.  Among the scheduler's
tasks is the allocation of system resources and the resolution of conflicts,
including crash recovery (system self preservation).

>Scratch Pad.  An area of main RAM set aside for use as a temporary storage
area for calculations or processes.

>Script.  A Command (BATch) File under Unix or DOS which can be used alone or
in combination w/ other Tools to perform some useful Task.  Under Unix such
Files are called "Shell Scripts".

>Scroll.  The smooth rolling up/down of CRT text as if the text were written
on a papyrus scroll.

>SCSI.  Small Computer Systems Interface.  The "Scuzzy" disk interface was
developed in the late 1970's by Shugart (who called it "SASI").  Originally
limited to 8 bit data paths and 1.5 Mbps burst rates, new versions w/ 16/32
bit paths and 40 Mbps burst rates are out for ANSI vote as a formal standard.
Originally considered a "toy computer" interface, SCSI is now the exclusive
disk interface for Apple, NeXT and SUN Workstations.  Recommended.

>Sector.  The pie-shaped physical area which, together with concentric
"Tracks" defines the location of "chucks" of information on a disk system.
See "Hard Sectored" (used by RK05 and RL02 Drives) and "Soft Sectored" (used
by everything else).

>Self Modifying Code.  A powerful and very dangerous programming technique in
which the program rewrites itself on the fly.  Impossible to maintain or
trouble-shoot. Avoid.

>Semiconductor.  Any material more conductive than an insulator and less so
than a metal.  By common usage, the crystalline forms of Germanium, Silicon
and certain other compounds (GaAs, for example) used in making electronic
devices, particularly diodes, transistors and microcircuits.

+Semiconductor, Mechanics of.  Crystal sets based on Galena crystals predate
vacuum tube radios by a decade.  It was long suspected that there was "magic"
in those crystals, but it wasn't until 1954 that it was understood that the
real magic was the crystal itself.  Those early devices were piezoelectric,
depending on electric fields created by the bending of the crystal around a
"cat's whisker".  They worked, but no one really understood why.

  A crystal is an electrical thing made of "bonds" (shared electrons) forming
a rigid "lattice" which is mostly empty space (a vacuum).  Electrons can
migrate through the lattice being handed from bond to bond or wander in the
empty space within the crystalline structure.  All crystals use both methods,
more or less.  If the "more" is with the free electrons, the material is an
"N" type.  If the lattice route predominates, it is a "P" type.  (If they are
equally active, it is called "Intrinsic", which is the "I" in "PIN" diodes.)

  The PN junction is the active area for all bipolar devices.  An intense
thermally powered electric field forms in that thin interface.  For Silicon,
it amounts to about .6V and is very real (and easily measured).  This "con-
tact" potential" is manipulated to cause bipolar devices to do useful things.
For example, adding to the field prevents current flow while subtracting from
it causes heavy conduction, i.e., the PN junction is a "diode".

  Semiconductors are thermally powered.  At low temperatures, they get kind
of "stiff" because few electrons get shaken out of their bonds to wander
around. On the other hand, at high temperatures the crystal vibrates so hard
that orderly conduction is impossible and the device experiences "thermal
run-away", which is why we test devices at both extremes.

  Bipolar transistors are actually back-to-back diodes.  The "Collector's" PN
junction's electric field is enhanced by VCC preventing normal current flow.
The "Emitter's" PN junction carries the signal current "injected" into the
"Base".  The Base has one problem: It leaks!!  For every electron of signal
current, over a hundred drift clean thru into the Collector.  Part of the
problem is that the Base is very thin.  Part of it is that the signal is
operating in the opposite conduction mode and it takes time to switch horses.
And there is very little time.  So each signal electron generates a hundred
fold response in the Collector circuit.  We call that "problem" amplifica-
tion.

  Devices that use both of the crystal's conduction modes are called "Bipo-
lar". That class includes all diodes and most transistors.  FETs use a di-
rectly induced electric field to control flow so only one conduction mode is
used (The other is strongly inhibited).  This is the technology used in
DRAMs, CPUs and other MOS or CMOS parts.  Even they depend on PN junctions
for isolation, so they also get tested at temperature extremes.

>Servo.  A closed loop control system which monitors the output to regulate
itself.  A special case of feedback systems.  Implies that the loop contains
items displaying inertia (mass or thermal mass or the like), a factor which
complicates the control situation.  Example: Home heating systems.

>Server.  A fully slaved operating mode under which the machine expects to
interact with another machine.  Implies a controlling program in the other
machine such that the linked pair respond as one.  Example: Kermit.

>SGML.  Standard Generalized Markup Language.  A book-binder's manual system
of embedded formatting commands resembling Unix's "troff" (Totally Ridiculous
Output File Formatter), a command language for Photo Typesetters.  User
hostile, labor/hardware intensive.  GSA has refused to impose SGML on Con-
tractors/Government Users as CALS has loudly demanded.  A Turkey. Avoid.

>Shadow Mask.  A component in conventional color CRTs.  A kind of "knothole"
through which the three electron guns peek to light their individual color
dots. A variation called a "slot mask" uses color stripes instead of dots.
Sony's "Trinitron" resembles the slot mask scheme except that only one elec-
tron gun is used and a control grid is substituted for the mask.

>Shelfware.  Software that resides where the name implies.

>Shadow RAM.  Semiconductor RAM backed by EEROM which automatically "burns"
an image of the data in the normal RAM in the case of power down (or power
failure) and restores it at power up, i.e., the combination is nonvolatile.
Expensive.  AKA NOVRAM.  See Also EEROM.

>Shareware.  Software distributed freely at no cost which asks users to
"donate" a token amount directly to the author.  Often of surprisingly good
quality, Shareware is usually authored by professionals who are contractually
inhibited from private "For Profit" ventures.

>Shell.  The name DOS/Unix gives to its command-line processors.  Far more
than a JCL, Shells provide a rich command set complete enough to be consid-
ered a programming language (Unix Shell Programs are called "Scripts").
Contrast this to DEC's MCR which provide just enough to allow the user to
"light up" an application program.  System V provides the "Bourne Shell" with
its familiar "$" prompt.  BSD provides the "C Shell" with a "%" prompt.  The
"Korn Shell" (No Joke!) is an attempt to combine the best of both.  Other
systems have borrowed the idea from Unix, notably MS-DOS.  Shells are so
named because they "wrap" around the actual physical system presenting a User
interface independent of actual implementation.  See Also SVID and Posix.

>Shell Script.  Any Unix Tool written in the "Batch" programming language of
the Shell.  DOS has a similar (severely limited) capability w/ its ".BAT"
files.

>Shmoo Plots.  A scatter diagram showing the interaction of two parameter on
(Pass/Fail) test results.  The resulting "Blob" is said to resemble the
"Smoo" character from Al Capp's "Little Abner" comic strip. (Shmooes look
like a cross between a marshmallow and a bowling pin (w/ eyes).  They are
lovable, eatable and said to taste like anything desired.)

>Sidetone.  The portion of a telephone conversation fed back into the receiv-
er to allow the user to "hear" himself speak.

>SIGGRAPH.  Special Interest Group in computer GRAPHics, a ACM working group
best known for the CORE graphics standard (1979).

>Signature Analysis.  An application of CRC techniques to digital circuit
testing (the CRC tag being the "signature" in this case).  Useful as a quick
verification of proper circuit operation, SA is less useful in fault isola-
tion once a mismatch is found.  Used primarily as a field maintenance tool to
localize the fault to a replaceable assembly.

>Simplex.  Data transmission in only one direction.  Occasionally used in a
loop configuration of tty stations.  Obsolete.

>Silicon.  Second most abundant element in the earth's crust, Silicon (Si) is
found in its pure oxide form in North Carolina's white silica sand which has
long been prized for the excellent glass it makes, its absorbent qualities
and (lately) for its low Boron content.  Elemental Silicon is made by the
electro-decomposition of fused (melted) silica sand.

  "Pulled" from the melt as a long rod-like single crystal, Silicon is blue-
grey with a metallic luster.  Zone Refining sweeps dissolved impurities to
the rod's end which is discarded.  To be useful for microcircuits, Silicon
must be almost atomically pure.  If Silicon atoms were grains of wheat, one
kernel of corn in a train of boxcars a mile long is grounds for rejection.

  Cut into 4 inch diameter "wafers" and polished to a mirror finish, raw
silicon is converted into microcircuits through a series of photochemical
processes.  Functionally tested w/ a "Prober", defective microcircuits are
marked w/ ink dots.  The wafer is then scribed w/ a diamond stylus and shat-
tered into "chips" which are sorted, bonded into DIP packages (or what-
ever).  Gold wires are ultrasonically welded to "bonding pads" on the chip
and the "lid" is put on, completing fabrication.  See Also Semiconductor.

>Silicon Valley.  A concentration of Hi-Tech industries which grew up between
Santa Clara and San Jose, California starting in the middle 70's.  Still a
"Boom Town" environment, this region (roughly centered on Mountain View) was
featured in the "James Bond" 007 Adventure "A View to a Kill".  Dallas has a
(smaller) similar region that grew up around Texas Instruments which is
called "Silicon Gulch".

>SIMM.  Single In-line Memory Modules.  A Chip Carrier Format for Lower
Density Memory Chips Used in Anticipation of Plug-Compatible High Density
DIP Availability.

>SLIP.  A Public Domain Serial Link (RS-232C) Internet Protocol (SLIP)
for TCP/IP systems.  Originated by 3COM, defined by RFC 1055 and included in
all BSDs since 4.2.  PC versions are generally part of some other package
(generally TCP/IP).  A public domain stand-alone version (KA9Q) was written
by Phil Karns.  MIT wrote SLFP (Serial Line Framing Protocol), a variation of
SLIP used widely on campus (including U of Michigan).  Slick.

>Smalltalk.  A computer language (actually a software environment) developed
by Xerox Palo Alto, representing a decade of continuous work.  First appear-
ing as a major product in the ill-fated "STAR" system, Smalltalk forms the
basis of most of Apple's recent magic, i.e., overlapping windows, detailed
graphics, icons and the "mouse" cursor controller.  The current version is
Smalltalk-80 (the third major revision).  Best example is the MacIntosh.

>S/N.  Signal to Noise.  The ratio of useful energy (the "signal") to noise.
Usually given in db.

>SNA.  System Network Architecture.  An IBM Master/Slave environment using a
large mainframe computer as the Master Controller.  Uses SDLC, a superset of
ANSI HDLC.  Probably the best modern master/slave scheme, SNA has become a
defacto standard and is widely used, especially as an upgrade for the older
BiSync systems.  Spiffed up a bit, IBM now calls it "SAA".

>SNOBOL.  An "Also-Ran" language which, like PL/1 and APL, has a small,
devoted following.  Particularly well suited for string manipulations, SNOBOL
features strong pattern matching constructs. The last widely distributed
version is Snobol IV.

>SneakerNet.  The exchange of information via compatible Floppies physically
interchanged among a small group of (local) Users.  To be successful, this
"Hoof-Powered" LAN must deal w/ most LAN issues (format, access, security,
integrity, updating, etc.).  So named for the tennis shoes favored by Bit-
Heads.

>Soft Error.  An error that can be corrected automatically without causing a
system fault.  In RAMs, an error caused by an alpha particle hit.

>Soft Sectored.  Said of flexible disks.  See Hard Sectored.

>Software.  The actual computer language statements or binary codes resulting
that cause the computer to do something useful.  Also called "code".  The
only thing "soft" about software is the name.  Everything else is hard.

>Software Maintenance.  The process of "patching" and upgrading (to reflect
improvements or changes) existing computer code.  Typically costs 5 times the
cost of the original development cost over the program's life cycle.  Also, a
programmer is 7 times more likely to introduce a bug during maintenance than
during the original development effort. (Source: IBM)

>Software Testing.  The art of proving that the bugs remaining are smarter
than the people attempting to eradicate them.

>Source Code.  The human readable statements written in some computer lan-
guage that comprise a program.

>Spindle.
>Spinning Storage.  A Hard Disk.

>Splatter.  CrossTalk.

>SPOOL.  (1962) Simultaneous Peripheral Operation On-Line.  Now a rather
sophisticated scheme for sharing printers/plotters by using special files
which capture the program's output and hold it until serviced by a "Spooler"
which dumps it onto the shared resource.

>Stack.  A pile.  An item placed on a stack is "pushed".  An item removed
from a stack is "popped".  Operation is on a first in, last out basis.

>Stacking.  Said of High Performance Hard Drives.  Broadsiding Bits onto
Multiple heads (surfaces) to Improve Throughput.  Risky (crash one head &
lose the whole works).  Effective. Expensive (and probably Worth it).
>Stagger.  A scheme to reduce the average rotational latency in disk systems.
If logically sequential disk blocks are arranged in physically sequential
order, the next disk block will already have begun to pass beneath the
read/write head before the system is ready to access it, i.e., one complete
revolution is lost. By physically offsetting logically sequential blocks, the
system gets ready to access the next logical block just as the beginning of
that block approaches the read/write head.  Staggering is established during
disk initialization and, properly done, can significantly improve system
throughput. AKA Interleaving.

>Standards.  They are a blessing and a curse.  At best, Standards provide a
framework for vendors to hang their enhancements (and Users, their hopes). At
worst, Standards stifle innovation (are too rigid) or allow so many "legal"
options as to be worthless (IGES).

  "Might" doesn't make "Right" but it does make (defacto) Standards. Centro-
nix Printer interfaces, EGA/VGA and VHS are examples.  IBM is so powerful
that EC made formal publication of IBM's internal standards (as AT&T does) a
condition of business license renewal.  These market-driven standards fill
immediate needs but tend to address limited situations that fade in impor-
tance with time (CP/M).

  Industry associations set Standards for their members (and by extension,
the rest of us).  Among these are ASTM, IEEE and EIA, the latter holding the
honors for the most successful (RS-232) and the least successful (RS-449)
Standards.  Formalization can give a defacto standard's creator a significant
advantage, which is why formal standards tend to punish independent innova-
tors. Courts have held Industry Associations (ASTM, specifically) liable for
anticompetitive formal standards.  (You must agree to license all comers at
a "reasonable fee" (HP's one-time charge is $250 for IEEE-488 rights).)

  When vested interests attempt to victimize the User, the Standards making
process can break down.  The current mess in Graphics resulted from a long
tradition of "locking in" Users through intentionally incompatible print/CRT
graphics formats.  No one (or few) formats generated enough market share to
become defacto standards.  Competing Standards bodies have proposed an array
of ineffective "Standards", none of which dominates.  Unless some new tech-
nology (such as X-Windows) can drive an effective Standard, we must look to
ISO or Japan for a solution.  GPIB and Ethernet became entangled in turf
battles in IEEE committees and "round-ended" ANSI via Europe (thru ECMA &
ISO) to become US Standards (IEEE-488 and IEEE-802.3, respectively)

  The real power of Standards is their ability to define markets, procure-
ments and sales.  EC's ability to restrict access to the European Common
Market has put real teeth in ISO standards (as IBM discovered).  FIPS like-
wise define Government markets.  DEC learned a $4.3 Billion Posix lesson
involving FIPS-151 and the AF Office Automation contract (AFCAC-251). (DEC
bought MIPS, joined OSF and loudly supports Unix, Posix, Gosip and ISO).

  Military Standards, like vendor's Proprietary Standards, tend to define
"Products" ala DECnet, SAA or SEM.  TCP/IP is an example of a MIL-Spec that
has migrated well beyond its intended application (ARPANET) to define a fast
growing market segment.  Until the EC crackdown, IBM played the Proprietary
Standards game with a vengeance, changing its internal standards at will to
gain market advantage.  In an increasingly buyer's market, closed standards
(DECnet) are being cracked open (ISO compliant) and open standards (Unix,
TCP/IP) are on a roll.

  The only constant is change.  Standards, good and bad, provide structure in
an otherwise fluid world.  Standardization is never complete, timely or
exhaustive.  Anyone who tells you otherwise is a liar and anyone who believes
him is a fool.  Standards are a high stacks crap-shoot.    Guess right and
the world comes to you (Unix).  Guess wrong and it gets very lonely (ATLAS).

>stderr.  Standard Error.  The Unix/DOS pipe used for error messages.  By
default, stderr prints to the user's terminal but may be redirected using the
&2> (Unix Shell) syntax.  Unlike stdin/stdout, DOS does not redirect stderr.

>stdin.  Standard Input.  The Unix/DOS InFlow Pipe for program input.  By
default, the User's keyboard.  May be redirected using  the '<' {Squirts IN}
symbol or a Pipe '|'.

>stdout.  Standard Output.  The Unix/DOS OutFlow Pipe for program text.  By
default, the User's CRT.  Often redirected using the '>' {Squirts TO} symbol
or a Pipe.  Under Unix, stdout is File Descriptor 1, so "&2>1" redirects
stderr into the stdout Pipe.

  Pipes and Stdio are now commonplace even under MS-DOS.  See Also Pipes and
Filters.

>Start/Stop.  Asynchronous serial data transmission ala teletype.  Original-
ly, a mechanical rotary switch clutched in by a "Step" signal built up the
serial bit stream which included a "Space" as the first bit to trigger the
clutch of the distant machine's selector mechanism that decoded the data.
The last bit (the "Stop" bit) was originally twice as long to allow time for
the mechanical parts to coast to a stop.  The receiver is resynchronized each
character cycle eliminating timing error build up.  AKA Asynchronous.

>Statistical Mux.  A multiplexer that depends on the statistical (bursty)
nature of terminal communications to time slice a single high speed channel
among several users. Nearly always an X.25 link.

>Stepping Motor.  A multiphase AC (actually pulsed DC) motor intentionally
designed to "cog".  Strong permanent magnets establish zero energy "rest"
positions.  Properly pulsed, the motor will advance the shaft a specified
number of degrees for each pulse, making it an ideal actuator for a digital
control system.  Widely used in printers, floppy drives and some (cheap) hard
disks. Frequently combined with cogged belts, screw drives or band actuators.

+Stonehenge.  The most spectacular and best known of some half dozen similar
sites in the British Isles, Northern Europe and North America (most notably,
the "Great Medicine Wheel" in Wyoming).  Modern computer analysis proves
these structures to be fully functional analog computers (the earliest com-
puters yet found) designed to predict the occurrence of solar and lunar
eclipses, events of great importance in primitive religions.  Stonehenge is
located in a latitude where the principle alignments form a nearly perfect
right angle (93 degrees), apparently a matter of considerable importance
considering the labor lavished on the site.  Writings predating the Roman
conquest of Britain mention a people who accurately predicted eclipses,
indicating active operation of these sites into historical times.  Claimed by
the Druids, Stonehenge predates them (and they exhibit no indication of
understanding its design or operation) making it likely that whoever built
these sites were dispersed by the Romans and displaced by the Celts from whom
the Druids descended.

>Storage Tube.  A variation of oscilloscope technology in which the trace
from a (usually) single-shot event is captured and temporarily stored on the
face of the CRT.  This is accomplished by using an insulated wire mesh behind
the CRT face plate.  The image is "painted" onto the mesh using a high power
"writing" beam which discharges the mesh wherever it is touched.  Low energy
"Flood Guns" sustain the glowing phosphor image by passing through the mesh
along the trace of the Writing beam.  Limited to small CRT's as the mesh
becomes fragile as the size increases.  Another type of Storage Tube is the
Tektronix BiStable Storage Tube, which uses a different principle.

>Store And Forward.  A service of PDN's.  Traffic is held in the system
temporarily until a channel can be opened to the addressee.

>Store-And-Test.  A popular form of functional testing in which the device to
be tested is exercised by bursts of (stored) test patterns at a high rates
("Fast Functional Testing") to simulate actual operating conditions.  The key
to this method is the test pattern set (See Vector Set) which both stimulates
the device and predicts its response thereby allowing fast Go/No Go test
decisions.

>Streaming.  Said of tape.  A method of rapidly recording large amounts of
serial data on magnetic tape using a narrow head which is stepped downward
each time the tape (usually in a cartridge format) reverses at the EOT marks.
Popular for backing up disk systems, especially Winchesters.  Also, a failure
mode for LAN nodes (won't shut up).

>Streams.  Originally, the serial flow of information within a Pipe.  Later
extended beyond "Named Pipes" to "Named Streams" (The flowing information as
opposed to the channel that contains it).  This led to redirection by name
rather than by file (origin/destination) or channel (pipe or port) and the
management of the information flow directly, with the machine handling the
necessary pipefitting.

>String.  Literally a "string" of text characters (originally handled as a
block without regard to content or context).  A type of variable popularized
by BASIC.

>Strong Type Checking.  A feature of certain languages which forces data
types to be disjoint.  For example, the number '1' (an INTEGER) and '1.0' (a
REAL (Floating Point) number) are computed/handled/stored in totally differ-
ent ways.  A bother.  This situation exists because of the complex manipula-
tions involved in dealing w/ Floating Point Numbers.  INTEGER math (which
operates within the confines of the CPU's basic word length) runs as much as
100 times faster.  Fortran originated this split personality, but provided no
scheme to enforce "Type" separation, an oversight that leads to many obscure
errors.  ALGOL-60 corrected this by a rigid type-checking scheme.  Be aware
that many useful real world tasks require violation of data types.

>Structured Programming.  A concept created to eliminate "GOTO's". Impracti-
cal.  Originated the 'IF-THEN-ELSE' and 'CASE' constructs and "Pretty Print"
now widely used.

>Stuck-Ats.  A class of digital circuit faults which may be represented as
hard shorts to either VCC or ground.  This class of faults, which can be
modeled mathematically, can be detected using test vectors generated by logic
simulators ala LASAR.  While the detection of a "Stuck-At" condition is proof
positive of circuit failure, the converse is a matter of some debate.  At the
bottom line, Stuck-Ats are detectable and, therefore, useful.

>Super User.  A "privileged" user who has the power to read any file, kill
any process, change any parameter or reconfigure the operating system. Im-
plies a System Administration role.  The Unix Super User is named "root".

>SVID.  System V Interface Definition.  A remarkable multi-volume document
that details exactly which commands are required and how they must interact
in order for the overall package to qualify as "System V Unix Compatible". As
has been demonstrated w/ earlier versions (Minix, Version 7), it is possible
to (painfully) write a SVID conforming system without a single line of AT&T
code.  NBS is working on a non-AT&T version of SVID which will become a FIPS.
See Also BSD and Posix.

>Swap.  Disk Swap.  The process of posting one segment of RAM to disk and
replacing it with another from disk.  A common process in a Virtual Memory
style of operation.  Slow.

>Swap Block.  A small (usually circular) adapter (which may fit atop a gener-
al purpose test fixture) containing the mounting connector for the device to
be tested and interconnect wiring to the ATE's test head (or general purpose
fixture).

>Sweet-Spot.  That portion of an ATE machine's performance envelope where
error is insignificant.  Testing in this region approaches a "Science".  ATE
machines are normally operated well outside this region pressing their per-
formance envelope.  Testing there is an "Art".  Readings become "representa-
tions" of the real world and everything must be viewed with respect to meas-
urement uncertainties, distortion and offsets.  The superior stability and
repeatability of ATE machines allows "Correlation", the validation of obser-
vations against accurately known benchmarks.

+System, Evolution of.  In the beginning, there was no alternative to working
in machine language, which at the time was of such low level that today it
would be called 'Microcode' (See Same.)
      _______________                   ______________
     |               |                 |              |
     |  File of      |  ------------\  | The Physical |  Example:
     |  Numeric Data |  ------------/  |    Machine   |    TI-553 ATE
     |_______________|                 |______________|
               Systems c1950 (ENIAC, EDSAC, UNIVAC I)


  The introduction of the IBM 650, which was essentially a "Four Banger"
using a rotating drum as a temporary memory (I/O was via punch cards) brought
something new, a utility program called an "Assembler".  This widely used
scientific machine set the standard for form, format and syntax for what has
come to be called "Mnemonic Assembly Language".
 _____________                _______________          _______________
|  Source     |              |  Binary       |        |     The       |
|   Text      | ----------\  |   Object      |------\ |   Physical    |
|    File     | ----------/  |    Code       |------/ |   Machine     |
|_____________|   Assembler  |_______File____|        |_______________|
              Systems c1953 (IBM 650 & All Assembly Languages)

  In 1954, IBM created an enhanced assembler capable of handling text in a
more human oriented manner.  They called this utility a "Compiler" and the
first language to use it was Fortran.  Like nearly all assemblers, the For-
tran compiler made two passes through the source file and produced machine
executable object code.  Since assemblers then in use allowed "Macros" (See
Same), Fortran included the capability to reference previously compiled (or
assembled) subroutines from a library.  This capability proved to be one of
the real strengths of the language and has contributed strongly to its wide
spread use.  Prior to run time, these sections were fetched into the object
file by a "Linker" (although some compilers include the Linker as the compil-
er's last operation).  These principles have remained virtually unchanged
since.
 _____________                _______________          _______________
|  Source     |              |               |        |     The       |
|   Text      | ----------\  |   Object      |------\ |   Physical    |
|    File     | ----------/  |    Code       |------/ |   Machine     |
|_____________|   Compiler   |______File_____|        |_______________|
         Systems c1954  (Fortran & All Compiled Languages)

  One of the problems with a Fortran style compiler is that the object code
is specific to one physical machine.  To assist in transporting Fortran
programs, a library of standard subroutine programs evolved into which hard-
ware specific code was grouped.  In time these became known as "Drivers"
since most of them related directly to some peripheral device (such as a
printer).  The system manager could add or change a physical peripheral by
rewriting only the driver subroutine, a major advantage.  Still, the object
code for an IBM mainframe will not run on a UNIVAC or a VAX, so separate
compilers must be written for each machine, an expensive bother.

  A 1960 experimental language, ALGOL-60, addressed the high cost of software
by designing a language to fit the compiler.  The resulting compilers were
much easier to write (making transportability better), ran faster and pro-
duced code much like hand generated assembly.  Unfortunately, the manually
inserted cues necessary to optimize the compiler resulted in a labor inten-
sive syntax. Recently, ALGOL-60 spinoffs (Pascal, Ada and 'C') have revived
this idea.  Of these, only 'C' (which was designed as an alternative to
mnemonic assembly language) posts a net labor savings over available alterna-
tives.

  Compilers evolved other ways, too.  One of these is the optimizing compil-
er.  Most compiler designs process source text one line at a time, generating
whatever object code is required plus a certain amount of overhead code.
Compiler generated machine language resembles a series of loops departing
from and returning to the "idle" machine state.  Assembly language, which is
fully incremental, is usually more compact and faster.  An optimizing compil-
er removes (or prevents the generation of) much of the overhead code associ-
ted with coming to and departing from the idle state, i.e., an optimizing
compiler's object code is much more incremental and much more like hand
generated assembly code.

  Incremental compilers progressed the opposite direction toward code com-
pletely line (or card image) oriented.  The intent was to reduce program
development cost and compiling costs by allowing the user to alter his pro-
gram on a line by line basis, recompiling only those cards (lines) that had
been changed.
 _____________                _______________          _______________
|  Source     |              |  Binary       |        |     The       |
|   Text      | ----------\  |   Object      |------\ |   Physical    |
|    File     | ----------/  |    Code       |------/ |   Machine     |
|_____________|  Interpreter |_____Buffer____|        |_______________|
    Systems c1962  (Dartmouth BASIC, LISP & Most Interpretive Languages)

  It was a short step from the incremental compiler to the source code inter-
preter which dispenses with the object code file completely.  This idea
evolved around 1962 and was incorporated into BASIC, a language emerging at
the time.  Early BASICs had a fixed number of variables and no array capabil-
ity. This was quickly solved using an 'Allocator' to mark out RAM space.
Interpreters have the ability to support debug features such as TRACE and
provide the user the option to easily repair a program.  This highly interac-
tive and User Friendly nature of interpreters has its price, speed.
 _____________                _______________           _______________
|  Source     |              |  Binary       | Inter-  |     The       |
|   Text      | ----------\  |   Pseudo-     |-------\ |   Physical    |
|    File     | ----------/  |    Code       |-------/ |   Machine     |
|_____________|  Translator  |_____File______| preter  |_______________|
             Systems c1971  (Tektronix 3270 ATE & Pascal)

  One solution to this situation is to use a "PseudoCode" (See p-Code).  This
technique is used by the Tektronix 3270 ATE which uses a "Translator" and
calls p-Code files type <TST>.  Made up of partly digested source text,
reformatted into what amounts to assembly macro calls ("Tokens") and point-
ers, they are expanded into executable machine language by an interpreter at
run time (IP3270.RUN in the case of TEKTEST).  The use of p-Code allows a
single compiler (translator) to service target machines which are greatly
different in design and construction.  Only the interpreter is machine spe-
cific, and it tends to be very small (typically only about 2-4Kb).  The price
paid is increased run-time overhead, which is why some implementations use a
true compiler on p-Code files to create "native object code" (executable
machine language).
 _____________                _______________          _______________
|  Source     |    Parser    |  Binary       | Inter- |     The       |
|   Text      | /---------\  |   Tokens      |------\ |   Physical    |
|    Entry/   | \---------/  |    In         |------/ |   Machine     |
|_____Display_|   DeParser   |_____RAM_______| preter |_______________|
      Systems c1976 (HP Rocky Mountain & MicroSoft BASIC)

  MicroSoft BASICA and the HP9845 use a modification of the source code
interpreter patterned after the p-Code/translator approach.  The "Translator"
is combined with the source program text editor to form a "Parser", which
does syntax checking and source text to binary token conversion as the text
is entered into the machine for storage.  Internally, the source text does
not exist.  To allow program listing and editing, a "DeParser" reconstructs
the original source text as needed.  Combined with an Allocator, the result-
ing system has the power of a compiled language, the User Friendliness of an
interpreter and the speed of a Translator based system.

  The HP-9000 substitutes a variation of the native code compiler for the
interpreter used in the HP9845.  The first time a line of code is accessed,
it is compiled into native code and stashed in scratch RAM.  The next time
the system accesses that line, a pointer points at the already compiled
object code thereby avoiding the performance penalty commonly associated with
an interpretive system.  If RAM is exhausted, all compiled object code is
dumped, and all jump pointers reset.  The effect is to keep only the current-
ly executing object code in RAM unless sufficient RAM exists to keep it all.
Given a fast processor, this technique provides the blinding speed of conven-
tional compiled object code and the User Friendliness of an interpreter.

  Paralleling the evolution of languages and language systems (compilers,
etc.), was the evolution of the Operating System itself.  The IBM 650 had no
"Operating System".  It simply read in punch cards, performed the indicated
operations and punched out the results (which is why most consider it to be a
"Calculator"..  UNIVAC I introduced the System Operator's Console from which
the System Manager could allocate RAM, assign peripherals and direct program
execution.  The CPU still did not run continuously (the Console operator had
to set/reset the program counter and run/halt the CPU as required), but the
basis for an operating system was being laid as a good Console man could
significantly improve system throughput by juggling several jobs in RAM so as
to avoid "Dead Time" while operators swapped tape reels.

  As systems became more complex, the Console operator became an observer.
The messages programmers included on the top of each deck (designated w/ a
'$' punched as the first character on the card so that it would print at the
System Console Terminal) containing information about which peripherals were
needed, how much RAM was required and how much time to allow (all factors the
Console operator needed to plan system work flow) became a standardized
syntax called a "Job Control Language" (JCL).  A "Monitor" program now read
the JCL cards and, using allocation algorithms, managed the actual system
work flow. Although the term would be coined later, these Operating Systems
were by nature "Multi-Tasking".

  The driving force behind Mainframe Operating Systems was the need to spread
the enormous cost of centralized hardware over many tasks.  Minicomputers
began in another direction as a result of a 1961 National Institute of Health
(NIH) contract that used a DEC PDP-1 (Serial Number One, as a matter of fact)
to service several terminals from one CPU (Time Share).  In the systems that
evolved from this root, the "Monitor" (as the Tektronix 3270 ATE still calls
it) program became self-sufficient.  JCL became "System Commands" entered at
the "System Prompt", '$'.  The few tasks the System Manager needed to accom-
plish were handled from an ordinary terminal (designated as "Console") via a
"Super User" mode which granted "Privilege" to perform global actions (such
as SYSCUP).

  Mainframes were (and remain) IBM's ballpark to the point that one frequent-
ly chose to limit transportability to protect a market niche. Besides, the
cost of rewriting compilers was an insignificant part of overall system cost.
Not so w/ minicomputers and a number of solutions evolved, including transla-
tors, cross-assemblers (assemblers creating native code for a different
("Target") machine) and "Universal" Operating Systems such as Unix and Pick.

  Microcomputers began (and primarily remain) single user systems.  Many have
integrated hardware and software to a degree found in no other class of
machine, intending to be "Appliances" which can be operated by anyone regard-
less of background or training.  The driving cost in micros has been software
and it is no surprise that the Operating Systems that have evolved (CP/M,
MS-DOS, SMALLTALK, etc.) are targeted at reducing the cost of creating,
transporting and supporting applications programs.  Superior as Graphics
Workstations, Micros have fueled the drive for practical LANs and clusters to
interlink themselves with other Micros and Mainframes to reduce the overall
cost of ownership and enhance throughput.

  Unix represents a divergent approach in which the "System" is really a
loose collection of executable files, each calling the next in sort of a
distributed state machine.  The logical extension of this is the so-called
"Stateless" system currently evolving for distributed multi-processor ma-
chines, particularly those of the "Cray-lett" class,

>System Second.  Also called a "Standard Billing Unit (SBU)."  A measure of
the amount of "computer power" used by your job (on a time shared system).
To maximize the rate of SBU generation, time share systems are specifically
designed to execute many jobs, each done slowly to avoid the I/O bottle-neck
problem and to maximize profits.  A good idea for the computer center.  Only
the user gets screwed.

>Synchronous.  Said of data communications processes.  A transmission tech-
nique in which the location of each bit is determined strictly on the basis
of time.  More susceptible to noise than asynchronous operation.  Almost
always used in high speed applications.  Used by Bisync and UTS-200 mode 4.

>Sysgen.  The process of building up a customized operating system.

>Sytek.  A proprietary broadband Metro-Net known locally as "CenterNet."
Based on groups of 20 135 Kbaud CSMA/CD channels, Sytek operates on the
"Mid-Split" principle under which all traffic is funneled into a frequency
shifter (the "Headend") and rebroadcast to all drops.  The cable plant is
standard CATV w/ bidirectional amplifier/splitters.  Operationally, Sytek
functions as a tele- phone system for terminals (virtual circuits), for which
it is well suited. PC's press its limitations quickly as maximum throughput
on any port is about 4.3 Kbaud.  The single best feature is the solid per-
formance EDAC provides. The greatest flaw is the remote programming "feature"
which can not be disabled.

                                    -T-

>T1.  An AT&T Standard for 1.544 Mb/s digital data stream channels.  Set up
in 1962, only recently of interest to end users.  A subset has been proposed,
the "Computer to PBX Interface" (CPI) which divides a T1 into 24 64 Kb/s
channels.

>Table Driven.  A variation of the Data Driven program in which a generalized
control program is guided by cues stored in a "Table" (usually a file or an
array), often the same table used to generate and interpret user menus.
Table driven programs have the advantage of being easily modified/ upgraded
(merely change the table), but typically execute slower and involve much more
overhead than normal programs.  Such programs are an implementation of
"Decision Tables", a software design tool based on an array of situations and
designated responses.

>Tape.  By common use: Magnetic Recording Tape.  A nonvolatile media composed
of a magnetic material (usually ferrite) bonded to a plastic ribbon (often
mylar).  Includes a lubricant to control head wear.  US Patented in 1942
(actually invented by BSR in NAZI Germany in 1934) , the original paper
backing proved too fragile.  Used widely as a media for audio signals (voice,
music, etc.) following WWII.  Developed as a mass storage media for computers
by IBM (replacing wire recorders, an older technology).  Tape has grown up
with computers and remains the media of choice for archival storage and bulk
data transfer.  See Nine Track.

>Tape, Cartridge.  Specifically, the 3M format.  A plastic enclosed dual reel
tape package using an elastic drive belt running on the back side of the
reels. A single drive wheel powers the combination which inherently provides
constant tape speed and tension.  Most popular in the minicartridge format
used in the HP terminals and desktop computers (9845/HP-85).  The original
quarter inch cartridge is enjoying renewed popularity as a Winchester backup
media (See Streaming).

>Tape, Cassette.  Specifically, the Phillips format originated for portable
audio recorders.  Marginal for digital use, but widely used in the home
computer market.  Elaborate dual servo hub drives and better materials have
allowed this format to serve in industrial applications despite inherent
speed/tensioning problems.

>Tape, 8 Track.  A half inch continuous loop format created for automotive
audio applications by Bill Lear, best known for his "Lear Jet" Executive
aircraft.  The 8 Track format is poorly suited to digital work (although the
Teradyne L115 uses them) but has influenced other designs, notably the Wafer
Drive and tape streamers, almost all of which use a incrementally positioned
head similar to the 8 Track scheme.  See Streaming.

>tar.  Tape Archiving program.  An old (but good) Unix Tool designed for
backups using 9-Track (Read-After-Write) tape.  Frequently displaced by
"cpio", "tar" lives on as a universal "squeezing" method widely used by
software distributors.

>TCP/IP.  Transmission Control Protocol/Internet Protocol.  A DOD developed
Public Domain suite of 5 protocols c1970 for ARPANET (Now DDN).  Although 15
years old, TCP and IP (the lower levels) compare very favorably w/ their ISO
counterparts.  The other 3 (applications level) protocols are definitely
dated: SMTF vs X.400 (Mail), FTP vs FTAM (File Transfer) and Telnet vs VTP
(Virtual Terminal Access).  Mandated for DOD phase-out by Congress, TCP/IP
has an installed base that is expanding at $500M/year w/ 1990 projections
seeing a $1.3 Billion market.  Delays in availability of ISO equivalents
(X.400 is to ship in late 88 w/ FTAM "Real Soon Now".  VTP is still vapor-
ware.) leave no alternative for near term users.  NBS has been tasked by
Congress to smooth the transition to ISO, a non-trivial task they are taking
seriously.

>TEKTEST.  The Test Table programming language of the Tektronix 3270 ATE.  A
superset of REDUCE.  Also, the name of the Operating System (c1971) of the
3270 ATE.

>TEKTEST, System.  The operating system for the PDP-11/3X in the Tektronix
3270 ATE system.  Created by gutting a standard DEC operating system c1971 of
its Emulator Traps (EMTs) and substituting others hardware specific to the
32XX ATEs.  A quick and dirty way to get a system on line, this put Tektronix
in the operating system business, a place where it has neither the expertise
nor the manpower to effectively be.  One of the reasons Tektronix needed a
special operating system is the curiously bottlenecked interface on the Test
Table, an 8 bit path routed through a data multiplexer originally designed to
operate from punched paper tape.

>Teletype.  Also "TTY".  A mechanical typewriter operated via a Current Loop
using a serial Start/Stop data stream.  Usually rated in Words/Minute (5
characters/word w/ one space).  Originally Baudot (5 level) code, now most
use ASCII (8 level). A 100 WPM machine operates at 110 baud (2 stop bits)
Obsolete.  Noisy.  Slow. Expensive.  Hard to maintain.

>TELEX.  A worldwide teleprinter dial network using Baudot Code (See Same)
teletype machines.  A similar service (TWX) offered by Western Union using
ASCII machines has largely displaced TELEX in the US.  The two networks are
interlinked.

>TEMPEST.  The unintentional radiation of information bearing EMI.

>Terminal Emulation.  The process by which one machine pretends to be a
"dumb" terminal operated by a human so as to interface with another (usually
remote) machine.  This is a "Real Realtime" interactive process which is very
difficult for most operating systems.  (Most machines assume the rest of the
world is their "peripheral").  Most language (like BASIC or Pascal) are
Line-Oriented.  Assembler (and "C") are character-oriented.  Terminal Emula-
tion is a mix since not all lines (prompts, for example) are terminated with
an EOL marker, a fact that will "hang" a Line-Oriented environment such as
the Unix Shell Script language.

>Texas Instruments 553 ATE.  An SSI to MSI tester c1968.  Designed to be
driven via punched tape read by a high speed optical reader using NCC (EIA)
code. Later retrofitted in some installations w/ a Texas Instruments model
960 computer, a relatively crude machine designed for business applications.
The TI-553 is programmed in a mnemonic machine language (a mixture of text
and numbers) which executes directly in hardware.  Fully incremental. Recon-
figurable via wiring on the test head adapter and on an "Undersocket Card", a
technique that greatly expands both its versatility and the difficulty in
understanding its programs.

>Threading.  A powerful Programming technique often abused.  The basis of the
power of FORTH and the reason for the bad press of the "GOTO" construct.
Unless controlled (as in FORTH), threading "stitches" together a program into
a single unit which can not be repaired or changed.  Thou Shalt Not Thread
Thy Code.

>Throughput.  The "bottom line" rate of data processing. transfer, etc.

>Time Share.  A style of operation under which a large central computer is
"shared" among many users via a time slicing scheme.  Invented in 1961 under
a National Institute of Health (NIH) contract on a DEC PDP-1 miniconputer
(Serial Number One, as a matter of fact).  Justifiable today only when the
task is primarily a telecommunication task.  Low performance.  High cost.
Frustrating.  Very user unfriendly.

>Time Slicing.  The most popular method of implementing Time Shared opera-
tions. Each User is allocated slivers of the CPU's time based on interrupts
generated by a Real Time Clock and some sort of priority scheme (to determine
who gets the next Time Slice).  See Also Transaction Processing.

+Think.  What humans do that machines don't.  Human thought is a combination
of analysis, synthesis and association with a healthy measure of wired in
error. This latter factor accounts for new and unexpected associations which
are then analyzed against criteria to determine if the errant response is a
"goof" or a "Flash of Genius."  Although the conscious mind "forgets" (loses
pointers), the subconscious mind (a kind of ever-running background task)
never does. Slower, this subsystem works strictly by association, sorting
through all experiences and memories putting together facts.  Unlike the
conscious mind, the subconscious mind is seldom wrong (although the situation
passed to it by the conscious mind may contain bad data).  This "smarter"
mind functions even while asleep, so the advice to "Sleep on it" is valid.
Humans temper their thought processes with a "value system", a kind of
"calibration" gained through experience.  Even if human thought is computer-
ized (and it can be), the problem will be one of trust.  Right now computers
are deterministic (they do what they are told, no more, no less).  Making a
machine non-deterministic (making it mimic human thought ala "Fuzzy Logic" or
whatever) requires the user to validate all its output (conclusions).  The
power to think and/or learn implies the right to make mistakes.  Is there an
application for a machine that makes mistakes?

>Token.  Specifically, the binary output of a Translator or Parser that is
later expanded into native machine language by an interpreter prior to execu-
tion.

>Token Passing.  An IBM scheme for controlling access to LANs based on a
special packet (the "Token") which empowers the holder to transmit (all
others listen.)  Favored by ADP types due to the resemblance of Polled Multi-
drop. Simple enough to explain, the protocol in practice is a nightmare due
to the inability of the LAN to handle noise. Requires a mainframe at one node
to serve as Master.  IBM claims to hold the basic international patent on
Token passing LANs, one of the conditions of which is to defend the patent
against all challenges.  The international patent is held by Swedish inventor
Olof Soderblom.  Avoid.

>Tool.  A small program written to do one thing well.  Intended to be (and
usually is) piped "Tinker-Toy" style w/ other Tools for use Barefoot or in
Command Files called "Scripts".  A good Tool will tell you its function and
Syntax if you enter its Name alone (or followed by a Question Mark).

>Transaction Processing.  A style of time share operation based on the as-
sumption that most User tasks ("Transactions") are very short, simple and
quickly accomplished.  Any running task is allowed to be interrupted by a new
task which is then allowed to run until it is either completed, suspended
(awaiting disk access usually) or interrupted.  If suspended, the task is
assigned a priority and the interrupted task restarted.  Each time a task is
suspended, its priority is examined and may be adjusted downward according to
some algorithm based on total run time.  The effect is to give Users very
quick responses for trivial tasks and to fade lengthy tasks into what amounts
to background execution automatically.  Since this scheme breaks down for
computationally intensive tasks (which rarely get suspended), Transaction
Processing is used primarily w/ DBMS operations.  A variation of "Hen &
Piglets", this system includes an abort timer to prevent any task from going
"Whole Hog".

+Transistor, History of.  Strictly speaking, the term "Transistor" covers the
generic class of solid state devices capable of performing linear signal
amplification (even though the circuit may use that device as a switch).

   Most mark the start of transistors with the 1948 invention of the bipolar
point contact transistor by John Bardeen, Walter Brattain and William Shock-
ley (for which they received the 1954 Nobel Prize), but solid state amplifi-
ers predate them by almost 20 years.  Julius Lilienfeld (1883-1963) applied
for patents on Thin Film FET devices in 1926 and twice in 1928 (being granted
one in 1929).

   Bell Labs went to some trouble to discredit his work in defending their
own (later) JFET patents.  Since Oskar Heil successfully patented a similar
FET design in England in 1935, there is little doubt that Lilienfeld's
work was valid, although neither his nor Heil's devices reached commercial
status. Bell's work resulted in the JFET (1952 by Shockley).

   Silicon MOS FETs were invented by Hofstein and Heiman working at RCA in
1962, just a little late to avoid the tragic loss of a generation of engineer-
ing talent well versed in working in a high impedance, voltage controlled
environment.

   Much has been made of the generosity of Bell Labs in licensing transistor
technology so widely and so reasonably from early on.  In actual fact, the
Bell system desperately needed practical solid state devices and the original
design, little more than a lump of Germanium w/ two sharpened wires poked
into it, wasn't even close.

   By throwing their invention out upon the waters of industry-wide innova-
tion, they gained rapid access to the device they needed, the silicon junction
transistor invented by Texas Instruments in 1954.

   The dividend was doubled when TI (and Fairchild) invented the integrated
circuit in 1958. (Strictly speaking, TI was first.  However, TI and Fairchild
actually solved different aspects of the same problem and cross-licensing
was required to produce a practical IC design, hence most credit them jointly
for the invention).

>Translator.  A stand alone version of a parser.  Functions like a compiler
except that the object file consists of binary tokens which must be expanded
by an interpreter prior to execution.  Used by the Tektronix 3270 ATE.

>Transmission Line.  Said of signal paths (usually metallic).  A path that
appears to be a infinite in length (no reflected energy).  Physical wires,
when terminated in the characteristic impedance of the line, emulate a resis-
tor of that value.  Coaxial cable, a popular transmission line, is normally
discussed in terms of the value of that resistance, e.g., "75 ohm" line is
used for TV and "50 ohm" line is used for CB.  Twist pair requires a 125 ohm
terminator.

>Trap.  An interrupt generated from software.  One way for an applications
program in a multiuser system to access shared resources (such as disks or
the floating point accelerator) safely.

>Trojan Horse.  An attack on system security based on a program that appears
harmless, but which contains a "Trapdoor" through which mischief can be done.

  Aside from the original, the most famous example of this probably was the
"Jesse James" who operated in the Kentucky/Indiana area following the Civil
War.  Actually a Pinkerton agent named "Charlie Biglow", this Trojan Horse
led many James associates (including the Younger Brothers in the Northfield,
Mn raid) into ambush, jail or worse.  Known as "Frank Dalton", the real
"Jesse James" was in retirement having accomplished the real-life Robin Hood
task of rescuing his kin's farms from the bank/railroad power axis that ran
roughshod West from St. Louis.  Protected by these kinfolk, Jesse never
ventured further East that Merimac Caverns or North beyond Red Oak, Iowa
where he staged the first successful robbery of a moving train.

  The way to deal with a Trojan Horse is to expose it and "kill" it so that
it can do no further harm.  In the case of Charlie Biglow, Bob Ford did the
honors on both counts.  Apparently a dead ringer, Biglow ran afoul of a
password scheme used by the core of the James gang (the remainder were hired
help).  Jesse had ridden w/ Quantrill and considered the fight against the
bank/railroad carpetbaggers to be a continuation of the Civil War (which it
was) and ran his show accordingly.  Once exposed, Biglow provided a means
to "Kill Jesse James" permanently.  Enlisting the aid of the Governor (who
ran on a "Law & Order" ticket) to the tune of $50,000, Jesse got a full
pardon, a one-way ticket to South America, and a rousing send off (the news-
paper photo shows him as the second pallbearer on the right leaving the
church).  Biglow got blasted and buried in Jesse's Mother's front yard, a
gravesite guarded to her dying day.  Bob Ford got a fair trial and a quick
pardon. The year was 1882.

   Exposing and "Killing" a Trojan Horse is only the first part of the task.
It WILL happen again unless firm measures are taken to close the security
breach. Often off-the-record handling of the offender (as was done w/ Pinker-
ton) is enough.  An aware user's group is the best security.  Reformed of-
fenders very often are the most effective system guardians.  When Jesse James
surfaced in Lawton, Ok at age 100, he had spent most of his 65 years of exile
as a lawman.   Sometimes a cowhand, sometimes caught up in Gold Rush fever
that swept him to places like Cripple Crick and Tombstone, he worked most
often as a deputy sheriff.  While Oklahoma was the "Indian Territory", he was
a deputy US Marshal there, ending up in Texas as a Ranger.  Before his death
at 103, Jesse revealed the above details and met w/ the last of the James gang
(two remained).  He is buried near Ft. Worth in a plot reserved for retired
Texas Rangers, marked by a CSA headstone: Jesse Woodson James 1847-1951.
                            (Source: UPI)

>TSR.  Terminate and Stay Resident.  Under MS-DOS, small programs may "park"
in scratch RAM and be "lit up" later using a keyboard escape sequence that
suspends main program execution.  Handy, but limited by interactions & RAM
availability.

>TTY.  Teletype.

>Tunneling.  The curious mechanism that allows certain electrons to vanish on
one side of a very thin insulator and reappear on the other as if they had
passed "under" the barrier.  Actually, they pass through it.  Quantum mechan-
ics allows very small objects (electrons) to shift between matter and pure
electromagnetic energy.  In other words, they "shine" through the barrier.
The band of transparency is very narrow and is related to the energy content
(electron-volts) of the electron, the angle of approach and the thickness of
the insulator.  Tunnel diodes were briefly popular in the early 1960's as
parametric (negative resistance) amplifiers and oscillators.  UV-PROMs use
this mechanism to charge their Floating Gates during "Burning".

>Turn-Key.  Said of systems.  Packaged systems (usually custom) which the end
user can operate without understanding the inner workings, rather like an
automobile, i.e., turn the key and it starts.

>Twist Pair.  Literally two insulated wires twisted together.  A quick, dirty
and surprisingly good transmission line having a characteristic impedance of
about 125 ohms.  Frequently overwrapped with a shield.  Frequently better
than coax for data transmission.

                                    -U-

>UART.  Universal Asynchronous Receiver/Transmitter.  A chip that performs
byte- to-serial bit-stream conversions.  Found in RS-232 "Serial" port hard-
ware. If the chip also supports "Synchronous" bit-streams, it is called a
"USART".

>UCSD Pascal.  An early (c1979) microcomputer implementation of Pascal writ-
ten by Kenneth Bowles of the University of California at San Diego.  A defac-
to standard even though seriously flawed.  AKA "Scud" Pascal.

>Unix.  An operating system created by Bell Labs licensed to Universities and
Software Vendors ("Wholesale").  Considered the best modern operating system
for scientific/technical users, although the almost cryptic syntax of its
"Shell" commands is intimidating (the Bell Labs Cheat Sheet is 14 pages
long!). Basically a conventional multitasking/multiuser implementation, Unix
extends "System Commands" into a powerful JCL (via a terminal command inter-
preter called the "Shell") featuring "Pipes".  A Pipe is a one way data path
to a file or another executing program (sort of a "LUN").  The user has the
option to "Pipefit" together small programs as building blocks, even though
they may be in completely different languages.  Unix is coded in 'C' for
portability and is supplied w/ a 'C' compiler (a language well suited for
building Tools) plus a "Toolbox" w/ 200+ canned utility programs (including a
Word Processor). Criticized as requiring large amounts of core (RAM) and disk
space, Unix supporting several users, each running highly "Piped" programs,
can quickly bring a system to its knees "Tool-Thrashing" (swapping temporari-
ly inactive programs to/from disk).  Unix imposes no file structure or lock-
ing mechanism (both being commonly added enhancements), does not support
Virtual Memory (or Cache) and can not support interrupt driven applications
(such as ATE).  AT&T Unix and Berkley Unix (which supports demand paged
Virtual Memory ala DEC VAX-11/780) are currently the two major variants.

+Unix, History of.  The name 'Unix' was coined by Ken Thompson of Bell Labs
for a (then) single user system home brewed for a cast-off PDP-7 to host the
game 'SPACE TRAVEL' after it loaded down a GE Multics system (c1968). Written
in assembly language, Unix evolved into a useful tool.  Transported to a
PDP-11/35 in 1972, Unix Version 2 (still in assembly) introduced "Pipes" and
multiple users.  An immediate hit, Unix migrated to other PDP-11 systems
throughout Bell Labs.  Unix Version 5 coded in 'C' (a kind of "Portable
Assembly Language") appeared in 1975 and spread into the university environ-
ment.  By the time Unix was formally licensed (as Version 7 in 1978), over
600 sites were already up and running.  Barred from retail sales, Bell li-
censed universities and software houses who added "Extensions" and remarketed
it as "XENIX", "HP-UX" or whatever.  After the breakup of 'Ma Bell', AT&T
decided to continue the policy of "Wholesale Only" licensing hoping that Unix
will become a formal standard.

---> Update 89:  Sun & AT&T were working hard on SVR6, a "closed" version of
Unix when an odd thing happened:  AT&T pulled down the largest open systems
contract ever (est. 4.3 Giga-Bucks).  Posix and SVID compatible, these
AFCAC-251 systems promise to catapult Unix into high orbit ala Zenith's Z-
248's.  Now AT&T is offering to license the trademark "Unix" to vendors
meeting the SVID regardless of whether AT&T code was used (licensed). Mean-
while back at the ranch, IBM & Amdahl are working furiously to port AIX to
IBM mainframes, HP bought Apollo (thereby gaining early access to the load-
sharing algorithm set to become and ANSI/ISO standard) and Sun is making tent
pegs out of DEC who bought MIPS (for Unix RISC Desktops).  UnixWorld's edi-
tors point out that no vendor has fielded a new OS since the IBM OS-2 Turkey
(new iron ports Unix).  The appearance of WordPerfect Ads in UnixWorld press-
es the real point: Unix has arrived.

+Unix, What's a.  Until Unix, it was generally accepted that an Operating
System exists primarily to manage system resources and to load application
programs.  If that's all you want, then Unix is as good as any.

   Talk w/ a "True Believer", however, and you quickly get the impression
that Unix is almost a Religous Experience, something profoundly different
from anything you have ever experienced.  It is and it isn't.  For perhaps
the majority of Computer Users, Unix isn't worth the bother.  Just load my
WordPerfect & get out of my life!

   For the few who know what they want to do and seek only to be allowed to
do it, Unix is the Ultimate Trip.  If you are a Tool Maker/User, if you
understand where you are going and if you are willing to leap off the edge
of sanity and safety into the freewheeling world of pure power, to sail or
fail by your own wits, Unix is akin to soaring unfettered into a cloudless
sky.  There are no limits.  There are no rules.  Pure Power.

   Heavy Duty!!  The key here is the concept of Tools and their Use.  Unix,
the system, is merely the playing field.  You, the User, select from hundreds
of Tools (Ginger has more than a thousand on-line), link them together
("Pipefit" them) and turn them loose on your task a few or many at a time.
Which Tools, how they are combined and how they are applied are completely
up to you.  So long as your task is accomplished, that must have been a
"Right Way" to do it.  There are many, many "Right Ways".

   Unix considers a "Good Tool" something that does one job well.  Since this
is kind of a judgement call, there are several tools that do similar things
and many others that do likewise as a sideline to something else.  That's
where the business of knowing what you want to accomplish comes in.
Beginners use (and abuse) only a few Tools.  Learn more Tools, have more
Power.  It never ends.

   Unix isn't so much a "Thing" as a  rough philosophy of how to do work
using computers.  Since Tools are written by different people at different
times with more or less talent and success (after all, even YOU can write
them), there are wide variations in syntax, action and safeguards.  A
"Tradition" and a few sets of "Regular Expressions" are about all you can
count on.  Some Tools are "Little Languages" like "awk" which, in a few
statements, can perform almost magical transformations on your data files.
Mastering these takes time.

   Perhaps the greatest contribution Unix has made is the vast pool of Unix
Users who have migrated onto "Normal" systems and, finding them lacking, have
back-doored pipes, Tools and the ability to use them into such diverse
nitches as MS-DOS, VAX VMS and even some IBM Mainframe environments.  With
this has come the "Open" idea that counters the long entrenched OEM concept
of "Closed", User Hostile environments intentionally made incompatible w/
everyone else.

   The "Brave New World" may well be AIX, Mach or some undiscovered Operating
System we haven't dreamed up yet.  Whatever it is, it will feel very familar
to Unix Users because not one new OS NOT based on Unix has made significant
market penitration since IBM's failed OS/2.  GOSIP/Posix merely document what
Buyers have decided: Unix has Arrived.

>UPS.   Uninterruptable  Power Source.  A Rectifier-Inverter  combination  w/
energy storage (usually NiCad or Gel-Cell Batteries) that provides some
sever- al  minutes  of "Ride Through" power.  Used in  Computer  applications
where power loss might result in grave damage (as in DBMS engines & File
Servers). In these applications, UPS "No-Break" power allows orderly system
shutdown.

>User Friendly.  A buzz phrase with a basis in fact.  A user generally views
a machine as "friendly" if:

  1. It performs (and fails) as expected.
  2. It plays "Fair" (no "Gotcha's").
  3. It allows a change of mind (a "Deselect" function).
  4. It is tolerant of human errors (without catastrophic results).
  5. It keeps the user informed of what's going on.
  6. It keeps the user firmly in control at all times.
  7. It responds quickly (ideally in 1.5 seconds or less).

>uucp.  Unix-to-Unix Copy Program.  Part of Unix "Flash Magic", uucp is a
deamon subsystem which can call other Unix machines (via LAN or dial lines),
log in (with passwords), exchange Mail, files and programs, and log out
without human intervention.  A real Mother Bear to set up, uucp runs slick as
glass, in effect making Unix machine quasi-networked.  Among its many magic
tricks is a router that can store-and-forward traffic for remote machine
(even though no direct connection exists locally).  The basis of UserNet.
Recommended.  Note: the "Nutshell" books are the key, don't even think about
setting up uucp without them.

                                    -V-

>V.32.  A CCITT standard for "SuperModems" capable of running 9.6Kbps on
Dialup Telephone lines.  Calls for 4/5 coded Trellis FEC w/ 5 state QAM Full
Duplex at 2.4Kbaud (12Kbps raw throughput).

>Vacuum-Column.  Said of magnetic tape drives.  A mechanical tape buffering
technology based on "Vacuum Columns", enclosed square pipe-like boxes open on
one end into which tape from the reels is sucked by negative pressure. Man-
aged photoelectrically, these temporary storage areas allow very high tape
speeds (up to 200 inches/second (ips)) w/ abrupt speed changes/reversals.
The physical inertia of the tape reels requires some form of buffering, the
three most common types being swing arm (mechanical) used up to 45 ips, short
column (vacuum) used up to 125 ips and long column up to 200 ips.  Recent
advances in short column design allow rates to 200 ips resulting in a more
compact form factor.  Some observers expect the long column to fade out as a
result.

>Vacuum Tube.  A depletion-mode N-Channel FET using vacuum as the semiconduc-
tor.

>Vaporware.  Undelivered promises, usually highly hyped. See "Real Soon Now".

+VAX-X.  Virtual Address Extended.  A family of mini/micro-computers from DEC
sharing a common operating system (VMS) and file structure.  Seriously over-
priced and under-powered, the VAX line is robust in hardware and strongly
supported in software.  Blessed with one of the strongest networking schemes
going (DECnet), the VAX line is pressing IBM in an area where IBM outfoxed
itself, connectivity.  Although DEC claims a "compatibility mode" exists, the
VAX line broke sharply w/ the PDP family leaving many users high & dry.

>Vcc.  The Main Power Source for a Solid State circuit.  The "cc" stands for
"Collector Common", a left-over from the discrete transistor days.  The Tube
equivalent was "B+", a left-over from the days of out-houses and Atwater-
Kents.

---> The "B" battery provided plate circuit voltage and was pretty stiff
(90V). The "A" battery was 3-6V used to light the filaments.  It was made up
of "A" cells about the size of beer cans.  These found their way into hand
cranked telephones ("Talk" battery), electric fence chargers and the ignition
of the Ford model "T".  The latter two applications fostered a quad-pac
called a "Hot Shot" which most farm suppliers still stock.  The "C" battery
provided the fixed tube bias used at the time (cathode bias came much later).
"C" cells are popular today.  In the late 1940's, RCA produced a portable
tube radio that used an "ABC" battery combination.  The "B" section was made
by stacking 10 9V subsections.  When transistor radios came along, these
were sold as "B Cells", an unwise designation since dropped.

>VDI.  Virtual Device Interface.  See GKS.

>VDM.  Virtual Device MetaFile.  A proposed extension to the GKS VDI standard
that defines a file format for "picture" files so that archiving and trans-
port can be supported in a multivendor environment.

>VDT.  Video Display Terminal.

>Vector Display.  Basically a fast oscilloscope used for high resolution
CAD graphics.  Information is written randomly onto the screen as line
segments ("vectors").  Superior to raster scan displays as there are no
"jaggies" in diagonal lines.  Expensive.  Subject to flicker as image
complexity increases.

>Vector Set.  Binary test patterns used to test microcircuits.  A "test
vector" is one kind of test pattern consisting of a "stimulus" section and a
"response" section.  A group of "vectors" comprises a "vector set".

>VHSIC.  Very High Speed Integrated Circuits.  A variation of VLSI with the
emphasis on throughput (speed).  Also, a formal US Navy program to develop
VHSIC devices in cooperation with industry (IBM, Sperry-Univac, etc.).

>Virtual Circuit.  A port to port link on a LAN emulating a metallic wire
path.

>Virtual Memory.  A trick to "fool" a computer into believing its disk system
is part of a huge RAM area.  Basically a trade of workspace size for speed.

>Virtual Memory, Operation of.  Virtual Memory interposes a "Memory Manager"
(a hardware device) that redirects memory fetches to one of several "Page"
areas in physical RAM via address offset registers.  If the fetch is from the
Page last referenced, virtually no delay occurs.  Otherwise the Memory Manag-
er must search for the referenced Page and the CPU is placed in a WAIT state.
If the needed page is not in physical RAM, the Memory Manager generates a
"Page Fault" interrupt which calls a service routine to fetch it in from
disk.

  There are two serious problems to be addressed.  The first deals with
selecting which Page will be replaced.  A random selection is easiest.  Cache
Managers (who work to/from slower physical RAM) often use this method as it
has little overhead and the penalty for guessing wrong (so called "Page
Thrashing") is small.  Disk Virtual Managers normally use a smarter method
called "Least Recently Used" (LRU).

  Under LRU, the Memory Manager's registers are arranged in a circular queue.
During a Page search, a pointer sweeps forward until the proper Page is
found. If the pointer wraps (passes its starting position), a disk swap is
needed.  A "USED" bit (set each time a Page is accessed) is examined and
cleared.  The first Page found w/o the "USED" bit set is replaced.

 That brings up the other problem.  If a Page has been altered in RAM, it
must be written back to disk.  Under LRU, this is indicated by a "Dirty" bit
(set during a write operation) checked during a Page swap.  Most LRU systems
have a background writeback routine so no Page remains Dirty long.  Some
systems (such as SRM) use "Write Through" (the Page goes "Busy" and writes
immediately to disk), a safer but higher overhead scheme less likely to catch
the disk in an indeterminate state during a system/power failure.  Most disk
"Track Buffering" schemes (a form of Virtual Memory also) use Write Through.

>Virus.  A small bit of binary meanness that sneaks into a system attached to
an executable file.  Once active, it replicates destructively.  Almost exclu-
sively a PC problem, virus attacks depend on permissive computer coupling
which allows casual copying of programs of uncertain origin.  Like bad gaso-
line, the cure is to flush the tank (disk), refill with product of known good
quality and exercise care in future acquisitions.  Although subject to damage
by viruses, data, text, batch and source code files can not spread the infec-
tion and may be freely exchanged.  Likewise, commercially distributed exe-
cutable are generally safe.

>VMS.  Virtual Memory System.  The Operating System of the DEC VAX line of
computers.  An excellent applications environment, VMS features a strong
hierarchical (layered) directory system.  Apparently a near optimum CISC
implementation, RISC versions have proven disappointing and have not been
marketed.  Currently (7/91) Not POSIX (FIPS-151) Compliant.

>Voice Coil Actuator.  A high performance head positioner used in flying head
disk systems.  Similar in construction to a speaker coil in a Hi-Fi "Woofer",
hence the name.  Expensive.

>VU.  Voice Unit.  A unit of measure on a ballistically weighted milliwatt
meter (0 VU in 600 ohms under a steady state signal is equal to 0 dbm) that
is roughly reflective of "loudness" to the human ear.

                                    -W-

>Warm Start.  A partial reboot of a system that, essentially, reloads the
terminal monitor so that the user can converse with the system after a
"crash".

>Whetstone.  A standardized test of overall computer system performance.
Said to reflect the actual performance doing real world tasks.  Written by
the National Physical Laboratory (England's version of NBS) based on an
analysis of 1000 ALGOL-60 programs, the 'Whetstone Instruction' is really an
average of 1000 language constructs arrange in a loop, one interaction of
which is considered to be "1K Whetstones", the accepted basic unit measure-
ment.  For example, a VAX-11/780 does about 1,133K B1D Whetstones/second
<Super-Mini Class Speed>. (By comparison, the VAX is also rated at about .25
MFLOPS).  See Also: Benchmarks

>White Noise.  Random audio energy distributed evenly across the band of
interest.  Sounds like a "Hiss".  Useful for filter testing.  The maximum
energy signal that a channel can carry.  High speed data is intentionally
coded to resemble white noise to improve the S/N ratio. AKA Gaussian Noise.

>White Space.  As defined by ANSI-C, a Space, Tab, Vertical Tab, NewLine or
FormFeed, i.e., items that might delimit Text Words.

>Widget.  Defined by X-Windows as a "Window Gadget", a gadget being an inge-
nious contrivance (per Webster's).  Widgets are the building blocks from
which "Windows" are made, i.e., the borders, scroll bars, banners, etc. that
we have come to associate with the X-Look.

>Winchester.  A hard disk technology based on lubricated recording surfaces
on which the heads alight as the disk spins down.  Originally the "code" name
for an IBM project to develop a 30 Mb disk using 30 tracks (hence, a 30-30
which suggested the famous Winchester rifle), the first commercial product
was a "40-40", but the name stuck.  Usually found in a fixed (non-replace-
able) sealed cartridge which has been assembled under clean room conditions
(may include an absolute filter internally). This sealed assembly is virtual-
ly immune to environmental contamination, making the Winchester disk popular
for office/ laboratory/home installations.  Fast.

>Windows.  Any of several multi-tasking methods (among them the Unix X-Win-
dows from MIT) that allows running programs to share the User's CRT, general-
ly by overlapping like sheets of paper ala Smalltalk (ala MacIntosh).  Win-
dows are visually flashy.  Windows requires that each program must maintain a
refresh image of its own output (a non-trivial task).  More frustrating,
Windowing systems impose strict boundaries on participating programs so that,
while the User sees multiple processes, the processes themselves are unaware
(and can not be made to be aware) of each other.  The strong bias of Windows
toward pixel-oriented techniques limits satisfactory operating to single-user
Workstations.

>WOM.  Write-Only Memory.  Logical inverse of a ROM.  A Bit Bucket.

>Word Length.  The number of bits in the basic instruction for the CPU.
Often multiples of 8 bits (a byte), although early machines used odd lengths.
In general, the longer the word length the "richer" the instruction set and
the more"powerful" the processor.  An 8 bit machine can directly address 64Kb
of RAM.  A 16 bit machine can directly address 4.2 Gb of RAM.  Beyond 16
bits, the extra measure of "power" comes from the ability to "multiplex"
operations into a few complex instructions and thereby cut down the fetch
rate from main RAM.

>WORM.  Write-Once, Read-Many.  Any of several Optical Disk technologies that
can be "burned" in the field.  Once written, the information is more or less
permanent.  Also called a "CR-PROM".

>Worm.  A class of stand-alone synthetic "Lifeforms" that may inhabit a
multi- user/multi-tasking DOS-based system.  Perhaps the best known is the
MIT "Cookie Monster" that appears on terminals at odd intervals demanding
that the user type the word "COOKIE".  Once "fed", it "goes away".  This
particular critter was well done, having the ability to alter its form to
avoid detection.  It also displays a "survival" instinct of sorts.  Unlike a
Virus, Worms are always intentionally inserted into a system, sometimes by a
remote user, often thru a security loophole.

----> Update 89:  The ARPANET "Virus" that crashed 6,000 BSD nodes was actual
a (poorly written) Worm intended to create a directory of ARPANET nodes via a
"chain letter" scheme.  BSD 4.3 was distributed w/ (at least) two security
"holes" which (when artfully accessed) allowed the Worm to Mail itself into a
node and gain "life" to reproduce.  The author made a Rookie error (he
allowed child processes to replicate) in his rush to get the Worm inserted
before updates closed the vital loopholes.  Though this was a "hacked" job,
the author has a PHD from Harvard and was working on another at Cornell.
(His father is Head Computer Security Honcho at NSA).

  A much more serious matter is CHAOS (yes, like in "Get Smart"), a German
computer group w/ ties to Eastern Europe.

---> Update 90:  Guilty.  Being Appealed.  Also, the whole story of the
"Hanover Hacker" has been published  ("The Cuckoo's Egg") telling how a
Berkley grad student, (Cliff Stoll) while tracking down a puzzling 75 cent
billing error, discovered an ARPANET hacker who roamed freely through DOD/NASA
systems while the FBI, CIA, NSA (etc) laughed.  Entrapped by the "Shower Head
Scam", the intruder turned out to be Marcus Hendick, friend of a "crack-head"
who sold information to the KGB.  Only the West Germans took the Berkley Hippy
Hacker seriously.  Exposed, the KGB burned their bridges (an empty gasoline
can was found in the woods near the coke-user's body).  Please Report Security
Breaches.  I don't think anyone thinks it's funny anymore.  The book is
Recommended Reading.

>WPM.  Words/Minute.  A standard word consists of 5 characters and one space
(the same as in typing class).  A 100 WPM typist outputs 10 cps.

>Writable Control Store.  A small, special purpose RAM into which user writ-
ten extensions to the CPU's instruction set can be posted.  Such extensions
are powerful, fast and difficult to write.  Found in high performance CPUs.
Little used unless raw speed in required.  Proposed by M.V.Wilkes in 1951.

>Write Protect.  A means of rendering a media read-only.

>Write Ring.  A ring shaped plastic tab which must be fitted into the groove
on the back of a nine-track tape reel in order to record on the tape.

>WYSIWYG.  "Whizzy-Wig" is short for the "Laugh-In" Punch Line: "What You See
Is What You Get" (c1970).  Now serious Jargon for CRT environments that
accurately reflect the layout/look of the completed hardcopy (document,
drawing, whatever).  WYSIWYG is User Friendly, which is why WordPerfect is so
popular and "nroff" (and CALS) is not.

                                    -X-
>X.  A client/server protocol which allows a destop terminal (see X-Terminal
below) to conduct several sessions with differnt hosts at the same time.

>X.25.  The CCITT standard for user terminals into a Public Data Network. A
packet switched technique, X.25 allows multiple users to share the same data
stream.  Rarely encountered at the User level, X.25 frequently is found
inside (and on the links between) Statistical Muxes since X.25 is, by nature,
a "Stat Mux" process.

>X3.64.  An ANSI standard for Terminal Control (Escape Code) functions.
Basically the defacto standard DEC VT-100 emulation slightly expanded.

>X.400 MHS.  The ISO LAN answer to TCP/IP's "Email" protocol.  Designed by
CCITT, X.400 is currently being viewed as an "Envelope" for ordinary Files, a
task it does well.  Unlike Email, X.400 is also a fully featured Page De-
scription Language, a feature expected to  be used widely in Europe.

>XENIX.  A trademark of MicroSoft for its version of Unix.  Announced in
1980, XENIX is generally considered the Defacto Standard Unix implementation
for microcomputers.  See Also Unix.

>Xerography.  A photoreproduction technology based on a photosensitive drum
(or belt) which is exposed to light reflected from the text to be copied.
Wherever light falls on the drum, the static charge sprayed on before expo-
sure bleeds off.  The drum is then washed over with a dry (or liquid) toner
which adheres to charged (dark) areas.  A controlled porosity paper is passed
by the drum and the toner image transfers.  The image is then fixed, usually
by heat.

>X-ON/X-OFF.  A flow control protocol based on unprintable control charac-
ters, generally DC1 & DC3 (^Q and ^S).  By popular use, the sender halts
transmission on when an X-OFF signal is received.  When the receiving end has
cleared out its buffer and can take more data, an X-ON signal is sent.
Originally intended to control the punched tape reader on a TTY machine, X-
ON/X-OFF became popular with the almost universal use of USARTs in serial
interfaces.  Simple and effective, X-ON/X-OFF is a common option in both
hardware and software, particularly w/ terminal emulators ala Kermit.

>X-Terminal.  An X-Windows compliant subsystem having .5-8 Mb of RAM and
powerful CPU(s) that off-load the location/sizing/hiding actions from the
host via a "client-server" convention.  In this case, the terminal is the
"server" (traffic cop) and the host's application programs are the "clients",
each of which believes it has a full screen X-Window to play in.  Since most
of the really bit intensive actions (shuffling windows, Zooms and Pops) are
local to the X-Terminal, comm link loading is much lower.  Acceptable per-
formance on 9600 baud modems has been demonstrated.

                                    -Y-

>YAM.  "Yet Another Modem."  A Public Domain modem control program.

                                    -Z-

>Zener.  The uncontrolled avalanche flow of current across a reverse biased
PN junction.  Once through a transition zone (called a "knee"), voltage
remains constant over a wide current range.  Unless externally limited,
current will increase until the device thermally self-distructs.  Widely used
as voltage references, spike suppressors and signal clippers, zeners also
find application in hardware random number generators (an A/D tracks zener
noise).

>Zmodem.  A 1986 public domain protocol from TELNET written by Chuck Fosberg,
the author of Ymodem (an extension of Ward Christen's Xmodem).  Zmodem is a
redevelopment using some of the ideas (but not the techniques) of its name-
sakes.  Zmodem is designed to press the throughput limits of a quiet, high
quality path (915 cps on a 9600 baud link), nearly 3 times better than Ker-
mit. Zmodem provides "Fall Backs" to Ymodem and Xmodem protocols at some
performance penalty.