Archive Magazine CD 1995/Archive Magazine CD 1995.iso/discs/prog_disc/volume_7/issue_10/glossary/GlossLF

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The purpose of a glossary in a book is sometimes
partly as a way of listing some of the basic concepts
covered in the book. That is not me intention here.
This glossary has been done on the basis that
someone may read a word or technical term or
abbreviation used in Archive magazine and think,
"What does XXXX mean?". If you think that, look
up the word in this glossary and it does not appear,
please ring, write or fax and tell us what you would
like us to add.
Paul Beverley 21/5/94

!
! -- (pronounced "pling") A term used to denote an
exclamation mark!

A
ADFS -- (Advanced Disc Filing System) This is the
proprietary system used by Acorn for organising
and storing data on floppy and hard drives.
AIM -- (Another Image Manager) A suite of image
processing software produced by Delft University
of Technology in the Netherlands.
Application -- The more general use of this word
means any job for which the computer may be used,
but it has a has a more specific definition. It is used
to refer to a directory (with a name beginning with a
"!") which contains a program or programs that
work under RISC OS to perform a particular func
tion. When the application is loaded, it usually
makes itself available to the user via an icon on the
righthand side of the iconbar.
Application directory -- Similar to an ordinary
directory in that it contains other files and direc
tories but its name starts with an exclamation mark
so that when you double click on the directory, it
starts up the application rather than just opening the
directory. To open an application directory, double
click with <shift> held down.
Apps icon -- This is an icon that appears on the
lefthand side of the iconbar (RISC OS 3 onwards).
It gives you access to a range of applications such
as Draw, Paint, etc that are provided with each
Archimedes or Risc PC computer.
ARM -- (Acorn RISC Machine) This is the original
name for the 32-bit RISC processor designed by
Acorn Computers Ltd. In the name "ARM Ltd", the
company formed between Acorn and Apple, the
"ARM" actually stands for Advanced RISC
Machine.
ASCII -- (American Standard Code for Information
Interchange) This is the most commonly used code
for representing text using 8-bit binary numbers.
ASIC -- (Application Specific Integrated Circuit) A
single chip electronic circuit that is specially
designed (by computer simulation -- what else?!)
for a particular application, e.g. to provide the logic
needed to interface a ’486 processor on a Risc PC
second processor card to the main ARM600 proces
sor and its address and data buses.
Assembler -- A compiler for converting a program
written in mnemonics into a machine code execut
able program.
AUN -- (Acorn Universal Networking) This does
not apply to a specific product or even a network
user interface but "the overall banner for Acorn’s
networking policy for the ’90s giving the strategic
direction of networking for Acorn computers."

B
Backdrop -- This is a desktop background which
may be a sprite or just a pattern.
Backplane -- A small printed circuit board with
connectors on it that allows you to plug in a number
of expansion cards.
Basic -- (Beginners All-purpose Symbol Instruction
Code) A commonly-used interpreted high level
language. It comes as standard on all Acorn
computers.
Baud -- This is a unit of speed for serial data trans
mission. 1 Baud = 1 bit per second.
BBS -- (Bulletin Board Service) A bulletin board is
an application run on a computer which stores
information and messages that can be accessed by
other computers, usually via the telephone line
using a modem. Many bulletin boards allow a
number of other computers to connect to the host
computer at the same time by using a number of
different modems and phone lines.
BIOS -- ??????
Bit -- A bit is the smallest unit of binary data. It has
two values, 0 and 1. A group of 8 bits of data
(referred to as a byte) could be used to represent a
single character using, most commonly, the ASCII
code or it could represent (part of) an instruction
that the computer would execute at some stage or it
could represent (part of) a number.
Bit-mapped (graphics) -- It is possible to represent
a picture on a computer by using a matrix of
(coloured) dots. The resolution of bit-mapped
pictures is limited by the numbers of dots used.
(This contrasts with vector graphics -- see below.
For example, the Paint application produces bit-
mapped graphics whereas Draw produces vector
graphics.)
Bpp -- (Bits per pixels) The number of binary bits
used to store the colour of each pixel.
Bubblejet printer -- This is a type of inkjet printer
where the patterns on the paper are generated by
squirting ink through a series of tiny nozzles in the
print head. Functionally, it is the same as an inkjet
printer.
Bullet -- A large black dot -- • -- used to highlight
something within some text.
Bus -- A set of parallel wires or PCB tracks along
which data is transmitted in a computer system. The
width of the bus
Byte -- A byte refers to (usually) 8 bits of binary
data stored within a computer’s memory or on a
data storage medium.

C
C -- A high level compiled language.
C++ -- This is an object-oriented version of the C
language.
CAD -- (Computer Aided Design) A computer-
based application that allows users to draw, design
and model engineering objects.
Caps -- Short for 'capitals'. See also small caps.
Capslock key -- This is a key on the lefthand side
of the keyboard. When it is pressed and the Cap
slock light comes on, all text typed into the
keyboard appears in upper case.
Caret -- A vertical bar in a screen display that
marks the point at which text will appear if it is
typed in from the keyboard.
CD -- (Compact Disc) A high density digital stor
age medium originally intended for hi-fi sound
reproduction but now applied to storage of text and
image data for various computer applications.
CDFS -- Filing system used for accessing CD-
ROMs.
CD-ROM -- (Compact Disc Read Only Memory) A
CD used for the storage of computer data. It is
called a ROM to emphasise that the data on the
disc, once written in the manufacturing stage,
cannot be modified.
CFS -- (Compression Filing System) This is a way
of accessing a data storage system through a
compression/decompression system such that it is
transparent to the user, i.e. the user need hardly
know that the data is being compressed and decom
pressed but just sees it as being read from and
written to the storage device.
Clear (files) -- A standard format for storing and
transferring 24-bit pictures.
Colour depth -- Every pixel on a computer screen
display has its colour defined by a certain number
of bits of data. The colour depth refers to the range
of different colours available for each pixel in a
particular screen mode. If a single bit were used, it
would only allow it to be one of two colours --
usually black or white. If it were defined by two
bits, it could have 4 (22) different colours, four bits
would provide (24) 16 different colours, 8-bit
provides 256 (28) colours, 16-bit gives over 32
thousand colours and 24-bit allows each pixel to
have any of about 16.7 million different colours --
about as much as the human eye can distinguish.
The 32-bit colour of the Risc PC "only" gives 16
million colours but the extra 8 bits can be used by
the computer to produce various different special
effects.
Command line -- All Acorn computers now come
with a WIMP interface. However, it is possible to
give the computer commands by typing them in
from the keyboard. If you press <f12>, an star
prompt appears. This is the command line. You can
enter commands such as CAT<return> to get a
catalogue of the current storage device.
Compiler -- In a computer language, instructions
that the programmer enters as (vaguely) understand
able words have to be translated into series of the
very simplest steps that the cpu executes. These
simple instructions are called machine code. The
job of a compilers is to take the whole of a program
and convert it into a single machine code program
which can be executed then or at a later stage. This
contrasts with an interpreted language in which
each individual line of the program is converted
into machine code as the program is running. In a
compiled language, you have to convert the whole
program before you can run any of it whereas in an
interpreted language you can run the program at any
time, stop it, change the program and run it again.
On the other hand, interpreted programs tend to run
more slowly because even if one line of the pro
gram is run many times, it has to be interpreted into
machine code every time it is run.
Compression/decompression -- There are various
mathematical techniques which can be used to store
computer data in a smaller amount of memory than
the uncompressed data occupies. Some of these
techniques are completely reversible so that the
decompressed data is identical to the original data.
However, in the case of images, it may be accep
table to allow a degree of degradation of the data in
order to increase the amount by which the data is
compressed.
Configuration -- A collection of settings and
option which describe how the computer will
operate when it is first switched on.
CPU -- (Central Processing Unit) This is the elec
tronic circuitry at the heart of a computer that
executes (very rapidly!) a series of simple steps of
reading, manipulating and writing information to
and from the computer's RAM memory and input/
output devices.
Crop marks -- In publishing, it is important to
define where a printed image appears in relation to
the edges of the paper. To do so, the images can be
printed on a larger sheet of paper and markers
placed on the sheet to show where the corners of the
paper will be.
CSV -- (Comma Separated Variables) A standard
way in which data is stored in a file where the items
of data are separated by commas.
CYMK -- (Cyan, Yellow, Magenta, Key) A method
of specifying colour by using the amounts of the
three primary (subtractive) colours plus the amount
of black (Key).

D
Database -- The definition of this word has
changed over the years. It used to mean a unified
collection of data files but now it tends to refer to an
integrated system of data plus the means of interro
gating and manipulating the data -- even to the
extent of referring to a database language.
Daughterboard -- See under 'motherboard'.
DEBI -- (DMA Extended Bus Interface) This is a
means of connecting expansion cards to the Risc
PC. (Depending on which magazine you believe, it
can support anything between 8 and 14 expansion
cards! -- I suspect it's 8 but I will check.)
Debug -- Remove the bugs (errors) within a
program.
Debugger -- An application written to provide
provide tools to aid the process of finding errors in
a program.
Decompression -- See compression/decompression.
Default -- The standard setting or option which the
computer selects unless the user has specifically
told it to do otherwise.
Device -- This is the technical term for any informa
tion storage medium (e.g. floppy or hard drive) or
transmission system (e.g. network, modem or
printer) that can be accessed through the computer.
Each currently available device is represented by an
icon at the lefthand side of the iconbar.
Dhrystones -- (strictly Dhrystones/second) This is a
means of indicating the speed of a processor by
testing the number of iterations it can perform of a
particular test program each second. For example,
the Risc PC 600 with a 30MHz ARM600 processor
can perform about 40,000 Dhrystones/second.
Dialogue box -- A window in which you are
expected to select various options and/or enter a
filename before the computer performs a particular
task or operation.
Digitiser -- An electronic circuit which takes an
analogue signal such as a sound of a video signal
and turns it into digital information which can be
stored and/or manipulated within the computer and
output again as a sound or video signal.
Direct drive laser printer -- In conventional laser
printers, the computer sends information to the
printer about what is to be printed, in what position
and with what styles etc. The processor and
memory in the laser printer are then used to work
out what dots to place where on the paper. In a
direct drive laser, by contrast, the computer works
out what the pattern of dots should be and then
sends the dot pattern down to the printer on a high
speed ("video") parallel interface. This means that
the printer need little or no memory of its own and
the process is faster because ARM processors tend
to be much more powerful than the processors used
in laser printers.
Directory -- When data is stored on a storage
medium such as a floppy disc, it can be grouped
into directories. When the iconbar icon is clicked, a
window appears showing the data in the root (i.e.
main) directory. This may be items of data (stored
as files), applications or other directories. These
directories in turn can contain more information
and/or further sub-directories. This system of
directories within directories is called a hierarchical
data structure.
Dithering -- When displaying a picture on a com
puter screen in, say, a 256 colour mode, it is
possible to give the impression of intermediate
colours by mixing dots of the different colours in
different ratios. This is done using a random dis
placement of these dots to avoid a patterned effect.
This technique is called dithering.
DMA -- (Direct Memory Access) When informa
tion is being taken into a computer from an external
source, the cpu normally reads a location, or block
of locations, in the external device and writes the
information into its own RAM memory. With
DMA, by contrast, the information is written
directly from the external device into the cpu's
memory without the cpu being involved. This
means that the process is much faster as the cpu can
be doing other things while the information is being
loaded automatically into memory.
Dongle -- This is a small electronic circuit usually
held in a plastic connector block that goes on the
parallel port of a computer. It forms an electronic
'key' that allows you to use a particular application
(such as Impression or ArtWorks). The application
checks every now and then to see if a dongle is
present and, if not, it shuts itself down and will not
restart.
DOS -- (Disc Operating System -- but also now
used as shorthand for DR-DOS or MS-DOS) These
are the operating systems most commonly used on
IBM PC computers and compatibles. They can be
used on Acorn computers by using the PC Emulator
or a PC expansion card or, on a Risc PC, a PC
processor card. They are command-line operating
systems, i.e. they do not use a wimp interface.
Double density floppy discs -- Discs that can store
approximately 800Kb of data when formatted.
dpi -- (dots per inch) On a desktop printer, the text
and graphics are reproduced by rows and rows of
tiny dots. The smaller the dots, the better the defini
tion of the resulting printout. This is usually
specified as the number of dots per inch that the
printer can lay onto the paper. The same idea is
used for scanning. When scanning a picture or
diagram, the grey level (see below) of rows of tiny
areas of the picture are assessed by the scanner. The
closeness of the areas being differentiated is
measured in dots per inch.
DPMS -- (Display Power Management Signalling)
When monitors are not being used, it is a waste of
energy to have them on at normal brightness. RISC
OS 3 supports screen blanking which helps to
reduce energy consumption, but some monitors can
accept special electronic signals from a computer to
tell it to drop into a very low power consumption
mode if it is not being used. This signalling between
computer and monitor is not available in all moni
tors although a lot of newer monitors are beginning
to provide it.
DPOB -- (Dual Processor Open Bus) On the Risc
PC, the processor(s) are held on separate cards
which plug into the main PCB or motherboard. It
can take two such processor cards and the dual
processor open bus is a way of allowing two differ
ent (or similar) processors to share the use of the
computer's memory and input/output and data
storage facilities.
DRAM -- (Dynamic Random Access Memory)
This is the most common form of RAM memory
used in computers today. 'Dynamic' is a technical
term which refers to the way in which the informa
tion is stored within the chips.
DSP -- (Digital Sound Processing)
DTP -- (DeskTop Publishing) As desktop compu
ters have increased in processing power, it has
become possible for them to handle both text and
graphics, to allow users to manipulate them on-
screen and output them to a printer. In this way,
"books" can be produced on a desktop computer --
hence the term 'desktop publishing'.

E
Econet -- This is a means of connecting two or
more computers together so that they can exchange
information and share the use of peripherals such as
printers. It is a type of Local Area Network (LAN)
developed in the early '80s by Acorn Computers
Ltd.
EEPROM -- (Electrically Erasable Programmable
Read-Only Memory) A form of non-volatile
memory that remains unchanged even when the
power is switched off but which can be altered in
situ by using appropriate electronic circuitry i.e. it
can be reprogrammed through software.
E-mail -- (Electronic mail) A means communicat
ing with other computer users via a LAN or through
a modem to a national or international computer
centre.
EPROM -- (Erasable Programmable Read-Only
Memory) A form of non-volatile memory that
remains unchanged even when the power is
switched off but which can be altered by using
ultraviolet radiation to erase the information and
high voltages to re-program it. (But see Flash ROM
and EEPROM.)
EPS -- (Encapsulated PostScript) This is a type of
computer-generated file containing the necessary
PostScript commands to reproduce the picture. It
usually includes a 'snapshot' of the picture that can
be used for positioning purposes. EPS is a defined
standard allowing output from one application to be
used within another.
Ethernet -- Another type of LAN, but much faster
than Econet. It was developed by Xerox Corpor
ation in the late '80s.
Expansion card -- (formerly called podules or
peripheral modules) An extra circuit board fitted to
your computer that will allow it to perform various
extra functions which cannot be done with software
alone.

F
FAST -- Federation Against Software Theft
File -- A collection of information gathered together
and given a filename to identify it. It is stored in a
directory in a filing system.
Filer or Filing system -- A system used to handle
the storage of information. The ADFS filer and the
SCSI filer are the two most common on Acorn
machines.
Firmware -- This refers to software, applications
and/or data which is stored in a ROM.
Flash ROM -- To change the contents of a conven
tional EPROM, the chip has to be removed and
erased using ultra-violet radiation. It can then be
electrically re-programmed. A flash ROM, by
contrast, can be re-programmed electrically in situ,
i.e. it can be reprogrammed through software.
Floating point numbers -- In order to represent a
wider range of numbers than can be done with
integers, and to represent fractions, computers use
floating point numbers. These use a number of
bytes (usually four) to represent the main part of the
number and another byte to represent the power of
two by which the number is multiplied.
Floppy disc/drive -- This is a data storage medium
consisting of a removable flexible (floppy) mag
netic disc in a hard plastic case. These discs can be
inserted as required into a floppy drive usually
housed within the case of the computer.
FMV -- (Full Motion Video) A term used to refer to
displaying video on a computer screen at full speed.
Acorn Replay provides FMV at 12.5 or 25 frames
per second.
Fonts -- Characters on the screen and on the printed
page can take on all sorts of different shapes and
styles. A font is a set of characters that have been
designed so that all the letters of the alphabet and a
whole range of other special characters (200 or
more in a complete set) have the same style. There
are also sets of related fonts using the same basic
style but with the characters angled (italic) or made
heavier (bold) or both (bold italic).
Format -- Formatting is preparing a floppy disc or
hard disc ready to receive data. Hard discs usually
arrive ready-formatted. Floppy discs may be for
matted in a number of different ways. Not all
formats of floppy disc can be read on all computers.
Without any extra software, Acorn computers can
read and write various Acorn formats as well as a
number of different PC and Atari formats. With
extra software, other formats, such as Apple Mac,
are also accessible on Acorn computers.
FPA -- (Floating Point Accelerator) This is a
hardware add-on to a cpu which enables it to do
floating point calculations more quickly.
FPE -- (Floating Point Emulator) If an application
requires full floating point calculations, it is poss
ible to run it on a computer that doesn't actually
have an FPA by emulating the FPA's functions in
software.
Function keys -- These are the set of twelve keys at
the top of the keyboard. What they do will depend
on the application currently in use.

G
Gb -- (Gigabyte) Approximately one thousand
million bytes of computer data. (Actually, it is 1K ×
1K × 1Kb = 230 = 1024 × 1024 × 1024 =
1,073,741,824 bytes.)
Genlock -- This is a device which enables the
output from the computer's video system to syn
chronised with a normal video signal so that
computer-generated text and graphics can be super
imposed on the video signal.
GIF (files) -- (Graphics Interchange Format) A
standard format for storing and transferring bit-
mapped graphics.
Grey levels -- A photograph may have some areas
completely white and some completely black. Most
areas, however, will be somewhere in between. If
you wish to represent that picture electronically,
you have to judge the 'greyness' of each part of the
picture. If you represent this on a scale of 0 to 15
(16 grey levels), it will not give such a faithful
representation of the picture as if 64 or 256 grey
levels were used. However, the more grey levels
used to represent each point on the picture, the more
data is being used. For example, in 256 grey levels,
a full A4 picture scanned at 400 d.p.i. could occupy
as much as 12Mb!
GUI -- (Graphical User Interface) At one time,
virtually all interaction between humans and com
puters was done on the basis of the human typing
words or codes into some form of keyboard. As
computing power became more accessible, it
became possible to provide a form of interaction
that was based far more on pictures (icons) within
windows on the screen. The user could then indicate
choice and initiate action by using a mouse or
trackerball to move a pointer around the screen.

H
Hard drive -- A case containing a number of rigid
metal discs covered with magnetised material that
can be used to store data; it usually has a capacity of
several megabytes or even gigabytes.
Hierarchical -- This is usually used in referring to
the data structure on storage media -- see 'directory'.
High level language -- This refers to a computer
language in which instructions that the programmer
enters are each converted into a number of machine
code instructions by a compiler or an interpreter.
Basic, Fortran, C etc are high level languages
whereas assembly language is a low level language.
High density floppy discs -- Discs that can store
approximately 1,600Kb of data when formatted
under ADFS or up to 1,440Kb when formatted
under MSDOS.
HSV -- (Hue Saturation Value) This is a colour-
picking system for use in DTP.

I
Iconbar -- The strip along the bottom of the com
puter screen that contains icons for devices (to the
left) and applications (to the right) that are currently
available to the user.
Icons -- Small pictures representing devices, files,
directories, applications, etc.
IDC -- (Insulation Displacement Connector) This
refers to a connector where the connection between
the contacts and the individual wires is made by
squeezing a row (or usually two rows) of sharp
metal teeth onto a ribbon cable so that the teeth cut
into the insulation and make contact with each
individual wire.
IDE -- (Integrated Drive Electronics) An electronic
standard method of connecting one or two hard
drives to a computer system. The standard was set
up to provide a simpler and cheaper means of
connecting hard drives to IBM and compatible
computers than was currently available.
Image processing -- If an image is stored on a
computer as binary data (such as a sprite file) it is
possible to manipulate the data mathematically to
enhance, distort, translate or otherwise modify the
picture in controlled ways.
Inkjet printer -- This is a type of printer where the
patterns on the paper are generated by squirting ink
through a series of tiny nozzles in the print head.
Input focus -- The output from the keyboard can be
directed to one and only one window at a time. The
window currently receiving information from the
keyboard is said to have the input focus. This is
indicated by the title bar of the window changing
from grey to yellow.
Interlace -- Build up a picture on a monitor screen
using two passes, each displaying alternate lines,
the aim being to reduce flicker effects.
Interpreter -- A type of high level language in
which each instruction is converted into machine
executable code line by line, as the program pro
ceeds. (See 'compiler' for more explanation.)
I/O -- (Input/Output)
IOC -- (Input/Output Controller) The I/O chip used
on pre-Risc PC Acorn computers was called IOC.
IOMD -- (Input Output Memory Device) This is a
computer chip designed by ARM Ltd which allows
ARM processors to control input/output devices and
to access memory.

J
JPEG -- ("Joint Picture Encoding Group" or, some
say, "Joint Photographic Experts Group") It is a
body set up in the USA to produce an industry
standard for still picture compression and storage.
The theory is that, with an agreed file format, one
company's decompression program can read the
files produced by someone else's compression
program.

K
Kb -- (Kilobyte) Approximately one thousand bytes
of computer data. (Actually, it is 210 = 1024 bytes.)
Kerning -- This refers to the spacing between
individual pairs of characters. To improve the look
of printed text, certain character pairs need to be
printed closer together than others.

L
LAN --  (Local area network) A general term for a
means of connecting computers together on one site
so that they can share information. Econet and
Ethernet are examples of LANs.
Letter box mode -- There are some monitors that
were never designed to display screen modes of the
like of Acorn modes 12, 15, etc. Some are com
pletely incapable of displaying them whereas others
can display them but with a somewhat reduced
vertical height, the shape being likened to the mouth
of a letter box.
Linker -- When using a compiler, this is the pro
gram that joins the object code from various sub-
programs, including the library routines, to form the
final executable machine code program.
Lisp -- A high level computer language often
associated with artificial intelligence programming.
Low level language -- A language which involves
programming the computer at the level of one
written instruction (or mnemonic) for each machine
code instruction.

M
Mb -- (Megabyte) Approximately one million bytes
of computer data. (Actually, it is 1K × 1Kb = 220 =
1024 × 1024 = 1,048,576 bytes.)
MEMC -- (MEMory Controller) The chip used on
pre-Risc PC Acorn computers to control the way
the cpu and video controller accessed the compu
ter's memory.
MHz -- (MegaHertz or Millions of cycles per
second) This is most often used to refer to the speed
of a computer's processor or memory. e.g. the Risc
PC 600 has a 30MHz processor which means that it
can carry out 30 million program steps each second.
Midi -- (Musical Instrument Digital Interface) A
defined standard for the physical link-up between
musical instruments and controllers, and also the
format of the data transmitted.
MIPS -- (Million Instructions Per Second) A
measure of how fast a cpu is running in terms of the
number of instructions it can execute each second.
Mnemonic -- A code used in an assembler to
represent a machine code instruction.
Mode -- See screen mode.
Modem -- (An abbreviation for modulator-
demodulator) It is a device which takes a serial
stream of computer data and converts it into audible
tones that can be transmitted down a telephone line
that was originally design for carrying voice infor
mation. It enables two computers to exchange data
at a distance via the telephone system.
Monitortype -- A computer variable that deter
mines which ranges of screen modes the computer
will attempt to display on your monitor.
Motherboard -- The main circuit board of a com
puter is sometimes referred to as a motherboard,
especially when, as in the Risc PC, many of the
functional parts of the computer are on separate
PCBs (sometimes called daughterboards) that are
plugged into the main or motherboard.
MPEG -- (Motion Picture Experts Group) A group
of technologists who are establishing an interna
tional standard for the compression of moving video
and its associated audio.
MTBF -- (Mean Time Between Failure) An indi
cation of how long, on average, it will be before a
machine goes wrong.
Multimedia -- A blend of communications ele
ments, usually computer-based, which allow
information in such forms as sound, speech, text,
still pictures, moving images and animations to be
presented to the user so that it can be accessed in an
interactive way, the user selecting which piece(s) of
information to pursue.
Multisession -- Information stored on a PhotoCD
can be added to at a later date with the appropriate
(very expensive) equipment. In order to read all the
information on these CDs, you need a CD-ROM
drive that is multisession capable.
Multisync monitor -- Some monitors are designed
(for cheapness) that only display only certain
display modes. Others can display a range of differ
ent modes -- they can synchronise onto a range of
different frequency signals and are therefore called
'multisync' monitors.
Multitasking -- An operating system like RISC OS
is capable of running a number of different tasks all
at the same time. This is multitasking.

N
Network -- A means of connecting a number of
computers together so that they can share data and
the use of peripherals.

O
Object code -- the machine-executable code pro
duced by a compiler.
Object oriented -- Any offers?!
OCR -- (Optical Character Recognition) Computers
can be trained to examine the shapes of typed or
printed characters and work out what the letters,
words and sentences are. So, combined with a
scanner or camera and digitiser, the computer can
'read' text off books and paper. Because of the
difficulty of being 100% accurate, it may take as
long to edit out the mistakes than to type the text in
from scratch so OCR programmers are fighting all
the time to make their programs more and more
accurate without becoming too slow for practical
use. This facility will become more viable as we get
progressively faster processors.
OLE -- (Object Linking and Embedding) This is a
means of linking data of different types (e.g. text,
drawfiles, sprites, etc) within one document so that
each element can be easily edited. Double-clicking
on an element brings up the appropriate editing
application (Draw, Paint, ArtWorks, etc) to allow
you to make the necessary changes without having
to export and then re-import the data.
Operating system -- This is the set of "house-
keeping" programs within a computer which handle
all the input/output, filing systems, etc. All modern
Acorn computers come with the RISC OS operating
system as standard (stored in ROM) but it is poss
ible to use alternative operating systems such as
DR-DOS and MS-DOS by adding the appropriate
software or hardware.
Option icon --  An icon that appears in a dialogue
box. Each time you click on it, you will switch a
particular option on or off.
OS  -- (Operating System)
Outline fonts -- These are fonts that are described
mathematically by using equations to define the
curves that make up the outline of the character's
shape. Using these equations, it is relatively simple
to work out how to display any font at any size,
either on the screen or on a printer where the shape
has to be reproduced as a series of dots.

P
Palette -- This is a set of colours used for the
desktop display. If the display has, say, 256 colours,
the palette determines which actual physical colour
is displayed on the screen for each of the colour
numbers from 0 to 255.
Parallel -- A device or communication channel is
said to be parallel if the data is sent several bits at a
time down several parallel wires -- the printer port
sends eight bits of data at a time.
Parallel processor -- In some computers, such as
the Risc PC, it is possible to have two processors
working side-by-side sharing the use of memory,
data storage and peripherals -- such processors are
referred to as 'parallel processors'.
Parent directory -- The directory within which the
directory you are currently dealing with is stored. (It
is the opposite of a subdirectory.)
Pathname -- This is the full name of a file or
directory including the filing system, disc name (or
number) and the sequence of directories that have to
be opened to access that particular file or directory.
PBM (files) -- (Portable Bit-Maps) A standard
format for storing and transferring bit-mapped
graphics.
PCB -- (Printed Circuit Board) A piece of insulat
ing material covered with conducting tracks used to
interconnect electronic components to make up an
electronic circuit.
PC Card -- A PC processor on a separate card that
can be used as a second processor in a Risc PC.
PC ISA Bus -- ???????????????
PC Emulator -- A software application that can
work within RISC OS or as a separate program
taking over the whole of the computer's processing
power which enables the computer to pretend to be
an IBM PC and run (most of) the programs that are
written to run under MS-DOS or DR-DOS on those
computers.
PC Expansion Card -- An expansion card contain
ing a PC processor plus memory plus some I/O
capability that can allow PC programs to be run
within the RISC OS environment.
Pentium -- This is a 32-bit cpu with a 64-bit data
bus produced
Peripheral -- An item of hardware such as a moni
tor or printer that can be connected to your
computer.
Pinboard -- This is an application that makes use of
the blank areas of the desktop. You can 'stick'
various files or applications onto it so that they are
easily accessible without having the filer windows
open for each of the directories in which they are
stored.
Pixel -- A tiny point of light and colour which is the
smallest picture element in a video or computer
image. The more pixels making up the image, the
better the resolution.
Podule -- See 'expansion card'.
PostScript -- A page description language used in
some laser printers and imagesetters. PostScript is a
defined standard so that applications using it can
produce output that can be printed on any Post
Script device.
Printer driver -- This is the program that converts
a document or file created by an application into
information that your particular printer needs to
reproduce the information on paper. The term can
be extended to "printing" a file or document via a
fax modem. The output is in the form which a fax
modem can then transmit, the printed output
appearing on the fax at the other end of the phone
line.
Printer manager -- An application that oversees
the printing process.
Prolog -- A high level computer language often
associated with artificial intelligence programming.
Processor -- See CPU.
PRM -- (Programmers Reference Manual) A set of
manuals covering many highly technical program
ming details of the RISC OS operating system.
Public Domain (PD) -- There are a number of
enthusiastic people who produce programs and
clipart which they want to make freely available for
other people to use -- rather than trying to make
money by selling them. The material is distributed
at cost by various individuals and agencies. There
are quite a number of PD libraries dealing with
material for Acorn computers. (Norwich Computer
Services runs one such library, part of which raises
money for charity.)

Q
Quit -- Close a file or application so that its win
dow(s) disappear from the screen and, in the case of
an application, it disappears from the iconbar.

R
Radio icons -- A group of buttons within a dialogue
box, only one of which can be selected at a time.
RAM -- (Random Access Memory) This is the
place within the computer where information is
stored on a temporary basis. When the computer is
switched off, information in RAM is lost.
RAM disc -- Part of the computer's RAM memory
can be set aside so that the user can store files and
data on a temporary basis during a computer ses
sion. The information is accessed through a filer in
the same way that you would access an external
storage medium such as a floppy or hard drive.
Relocatable module -- A section of computer code
that can be used to extend the facilities of the
operating system and which can then be used by
any application running in the computer.
Removable hard disc drive -- This is cross
between a hard drive and a floppy drive. It uses a
solid metal disc so that it can store large amounts of
data (currently up to 270Mb on a single disc) but
the disc is held in a plastic case like a thick floppy
disc and it can be taken in and out of the drive so
that a number of discs can be used for different
purposes, and the data can be transferred easily
from one computer to another.
Resolution -- The complexity of detail that can be
seen on a computer screen or a printer can be
specified in terms of resolution, i.e. the numbers of
dots per inch.
Resources -- The various programs and data files
which an application uses to perform its task.
RGB -- (Red Green Blue) Any colour can be made
up of a combination of different amounts of light of
these three primary colours. So colour monitors
(RGB monitors) use sets of thre coloured phosphor
dots of these three colours.
RIP -- (Raster Image Processor) This is a device
used in the printing industry to produce a high
resolution something-or-other... (Any offers of a
definition?)
RISC -- This is an acronym for Reduced Instruction
Set Computer. Companies like Acorn realised that
the trend to more and more complex computer
processors wasn't necessarily the best way to
increase the overall speed of computer processing.
These complex processors were spending the
majority of their time doing simple tasks anyway.
What Acorn did was to make the processors sim
pler, which meant they could work much faster
doing the simple jobs like pushing text around and
drawing dots on the screen. This is partly why RISC
processors are so well-suited to DTP applications --
though the explanation is grossly over-simplified!
RISC OS -- This is the operating system used on
Acorn's RISC-based computers.
RMA -- (Relocatable Module Area) The area of
RAM set aside for the program modules used by
different applications.
ROM -- (Read-Only Memory) A form of non-
volatile memory that remains unchanged even when
the power is switched off and which cannot
(usually) be altered. (But see Flash ROM and
EPROM.)
Root directory -- The main directory of a storage
device which contains all other directories and files
and which is displayed when the iconbar icon of the
device is clicked.
RS232/RS423 -- These are two different (but
similar) electrical standards for the transmission of
serial data.

S
Sampler -- An add-on that takes a sound signal as
input and turns it into digital data that can stored
and/or manipulated within the computer and then be
output again through a DAC (digital to analogue
converter).
Scanner -- An add-on that enables the user to read
visual images into the computer from originals such
as photographs and books.
SCART -- (Syndicat des Constructeurs d'Appariels
de Radio et de Television -- well, you wanted to
know, didn't you!) A means of connecting compu
ters, video recorders, etc to televisions and monitors
using standard connections.
!Scrap -- A special directory on which RISC OS
makes available for applications to use as temporary
storage space. Use of this directory is under the
control of the application and the user is normally
unaware of it.
Screen blanking -- Within RISC OS 3 is an
optional facility (set in the configuration) which
switches the screen to black after a user-definable
length of time if the computer is not being used. As
soon as a key is pressed or the mouse is moved, the
screen returns to normal. This reduces the likeli
hood of monitors having patterns 'burned in' to the
face of the tube (and reduces the power consump
tion of the monitor to some extent).
Screen mode -- Information can be displayed on
TV or monitor screens in a number of different
formats. The numbers of pixels that make up the
screen may be different (from, say, 480 × 512 to
1600 × 1200 or more) and the colour depth of each
pixel may vary. The amount of memory used to
display the screen will increase as both the number
of pixels and the colour depth are increased. There
is a trade-off between the two as the amount of
video memory is usually limited. A particular size
and colour depth is referred to as a screen mode.
Scrolling -- If a file or document is too large to be
displayed on the screen all at once, it is displayed in
a window with scroll bars and scroll arrows so that
you can move around and view different parts of it
as necessary.
SCSI -- (Small Computer Systems Interface) This is
an agreed standard system for communicating data
between computers and data storage and acquisition
devices, the data being transmitted along parallel
data paths. It is commonly used to link a computer
to hard drives, CD-ROMs and/or scanners, but it
can also be used to link computers together subject
to the limitation that you can only link a total of
eight different 'devices' together.
Second processor -- In computers such as the Risc
PC it is possible to have more than one processor
working together sharing memory, data storage and
peripherals. In the Risc PC, the ARM610 takes
charge when the computer is first switched on and it
then allows the other processor (the 'second proces
sor') access to memory etc.
Self-test -- When a computer is switched on, it runs
through a series of tests to check, as far as it is able,
that it is functioning correctly. In a RISC OS 3 (or
later) computer, if any of these self-tests fails, it will
usually issue some sort of error message. If the
system has not managed to get as far as producing a
working display on the VDU, it will send a coded
message about the likely error by flashing the LED
on the floppy drive.
Serial -- A device or communication channel is said
to be serial if the data is sent sequentially, one bit at
a time, as opposed to being sent several bits at a
time down parallel wires.
Shovelware -- This is a derogatory term for soft
ware and other data of inferior quality that is used
to 'pack out' a CD-ROM and make it up to 600Mb,
or whatever, to convince the potential purchaser
that the disc is worth buying.
Shutdown -- A menu option on the task manager
iconbar menu which 'clears up' the computer prior
to switching it off.
SIMM -- (Single In-line Memory Module) An
industry standard plug-in memory card as used in
the Risc PC, for example.
Slice -- (Single Layer Item of Computer Expan
sion!) The name applies to a single extra layer of
case in a Risc PC. It includes a new backplane with
two more slots than previously and four locking
pins longer than the ones they replace.
Smalltalk -- A high level computer programming
language that allows you to use object-oriented
techniques.
SOHO (market) -- (Small Office Home Office) A
defined market into which companies try to sell
their computer goodies.
Source code --  the name given to the program
written in a high level language which is converted
by a compiler into machine executable code.
Sprite -- A graphic made up of coloured pixels.
These can be
SQL -- (Structured Query Language) Language for
extracting information from a database.
Subdirectory -- Within any directory, you can store
files and other directories. A directory that appears
inside another directory is referred to as a
subdirectory.
SVGA -- (Super VGA) An enhanced colour
graphics standard from the PC world -- 1024×768.
System application (!System) -- An application
that contains many of the resources that can be used
by any or all other applications.
System disc -- A floppy disc containing a copy of
!System.

T
Tapestreamer -- Computer data has, for many
years, been stored on magnetic tape. This is a
basically inefficient method in the sense that if you
are at one end of the tape and the data you want is at
the other end, it can take a long time to reach the
information. However, it is very efficient in the
sense that the medium, magnetic tape, can be very
inexpensive per megabyte. A tapestreamer is a
glorified (video) tape recorder controlled by the
computer and is used mainly for backup storage
purposes.
Task manager -- This is the Acorn icon at the far
right of the iconbar. It is an application that controls
the allocation and use of memory within the
computer.
TCP/IP -- (Transfer Control Protocol / Interface
Protocol) This is a standard protocol for transferring
data between different computers on a LAN or via
modem link.
TIFF (files) -- (Tagged Image File Format) A very
versatile format for storing and transferring bit-
mapped graphics.
Title bar -- The bar along the top of a window that
contains the name of that window.
TLB -- (Translation Look-Aside Buffer) This is
part of an ARM processor which helps it to access
different areas of memory more quickly. Basically,
it's the bigger the buffer the better!
Tokenised -- When a Basic program is stored on
disc, it is usually stored with each keyword repre
sented by a single byte rather than as a string of
ASCII codes. These single bytes are referred to as
tokens.
Toner -- This is the fine powder used in a laser
printer (or photocopier).
Tracking -- In some applications, the spacing
between individual letters within a block of text can
be controlled -- this is called tracking. If the track
ing is changed, the spacing between all the
characters is increased or decreased. This is distinct
from kerning which relates to the spacing between
individual pairs of characters.
TRM -- (Technical Reference Manual) Term used
to refer to the optional hardware manual for Acorn
computers.
TSV -- (Tab Separated Variables) A standard way
in which data is stored in a file where the items of
data are separated by tab characters.

U


V
Vapourware -- A derogatory term for software that
is being advertised but isn't actually available --  it
is often said to be available "real soon now"!
VDU -- (Visual Display Unit) The monitor or
television used to display the output of the
computer.
Vector graphics -- It is possible to represent a
picture on a computer by using a series of lines,
shapes, characters etc. When such pictures are
printed, the resolution of the pictures produced is
only limited by the resolution of the output device.
(This contrasts with bit-mapped graphics -- see
above. For example, the Draw application produces
vector graphics whereas Paint produces bit-mapped
graphics.)
VESA -- (Video Electronics Standards Association)
VGA -- (Video Graphics Array) A graphics
standard from the PC world -- 640×480.
VIDC20 -- (Video Controller) The video and audio
controller designed by ARM Ltd and used in the
Risc PC.
Virtual memory -- A method by which an appli
cation, which requires more RAM memory than a
computer actually has, can still operate. It is done
by using parts of a hard drive's memory as an
extension of the real memory, the information being
swapped in and out by the operating system, as and
when it needs to be accessed by the application.
Virus -- A computer program which can replicate
itself (unbeknown to the user) in various storage
devices and in several places on one storage device.
As discs are taken from one computer to another,
the virus can be spread to more and more compu
ters. Often, the effect of these programs is to cause
malicious damage to data within the computer
system.
VRAM -- (Video RAM) This is a bank of high
speed RAM used to store the information for the
screen display. It can usually (as in the Risc PC) be
accessed by the computer's processor and by the
video controller at the same time. The computer
accesses it as necessary to change the screen display
and the video controller accesses it on a continuous
basis to constantly generate the signals the monitor
needs to display the information set up by the
computer.

W
WIMP -- (Windows, Icons Mouse and Pointer) A
method by which a user can interact with a compu
ter without having to learn lots of special words. It
provides a much more intuitive 'view' of the compu
ter and its facilities than non-WIMP operating
systems provide.
Winchester -- Old-fashioned term for a hard disc,
named after the inventors of the technology.
Word -- A group of bytes considered by the cpu to
be a unit of data. In Acorn 32-bit computers, a word
is
WP -- (Word-Processing) -- In the early days of
microcomputers, all they could do was allow you to
handle text to create documents, i.e. to process
words. These days, however, many of the programs
that are referred to as word-processors can also
handle pictures, so the distinction between WP and
DTP is becoming less clear.
Writable icon -- A submenu into which you can
type some information such as a filename.
Write-protect -- Open the tag at the corner of a
floppy disc in order to protect the contents from
being edited or accidentally deleted.
WYSIWYG -- (What You See Is What You Get) In
the days of text-based word-processing, the screen
display would only gave an indication of which
words would appear on a given printed page but
often not much more than that. WYSIWYG
describes a system where the screen display shows
the size and positioning of all the text (and
graphics) exactly as it will appear on the printed
page.
Whetstones -- (I think) This is a floating point
version of the Dhrystones test.


Sources
I acknowledge, with grateful thanks, the many
Archive subscribers who have contributed ideas and
definitions for this glossary. I would also like to
acknowledge various books that I have consulted
that have been most useful in compiling this
glossary:
Acorn Risc PC Welcome Guide -- Acorn Compu
ters Ltd -- 1-85250-143-X
Archimedes World Magazine -- various issues
DTP at a Glance -- Rob Pickering -- Bookmark
Publishing -- 1-85550-002-7
RISC OS First Steps -- Anne Roney -- Dabs Press