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1989-02-23
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Chuck Forsberg
The High Reliability Software
User Manual for
ZCOMM
Universal Line Printer Edition
ZCOMM Communications Software
Featuring
TurboLearn(TM) Script Writer,
Cybernetic Data Recovery(TM), Error Containment(TM),
and
OverThruster(TM)
User Supported Communications Software Tools
User Manual for
ZCOMM
Universal Line Printer Edition
Copyright 1989 Omen Technology Inc
All Rights Reserved
Omen Technology Incorporated
The High Reliability Software
Box 4681 Portland Oregon 97208
VOICE: 503-621-3406 :VOICE
TeleGodzilla Modem: 621-3746 Speed 1200,2400,19200
Compuserve:70007,2304 GEnie:CAF BIX:cforsberg
UUCP: ...!tektronix!reed!omen!caf
c 1984, 1985, 1986, 1987, 1988, 1989 Omen Technology Inc. All Rights Reserved.
(C) 1988 Omen Tech Inc Chapter 0
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 2
1. INTRODUCTION
Get a Handle on the Information Explosion with
ZCOMM(TM) User Supported Communications Software
ZCOMM helps collect, control, and transmit information with a minimum
of time, hassle, and expense. Concise commands and unobtrusive
displays facilitate telecommunications instead of distracting.
1.1 Data Capture
ZCOMM captures text with many choices of parity bit and control
character editing.
ZCOMM's Full-Time Capture Buffer(TM) saves scrolled data other
programs lose. You can scroll, page, and string search to cut and
paste captured information.
Omen's Error Containment(TM) technology minimizes errors caused by
line hits, and their effects on automatic scripts.
When necessary, ZCOMM can capture binary data without protocols.
ZCOMM does not limit the length of captured files.
1.2 File Transfer Protocols
Years of communications experience distilled in ZCOMM provide rapid
file transfers with unmatched reliability. Unsolicited customer
testimonials chronicle accurate file transfers under conditions that
crash the other programs, thanks to Omen Technology's Cybernetic Data
Recovery(TM) compatible logic enhancements and thorough protocol
stress testing.
ZCOMM's protocols are more cost effective than the minimal, unreliable
XMODEM support available with other programs. They are easier to find
and more useful than undocumented proprietary protocols.
1.3 ZMODEM: The Sate of the Art in File Transfers
ZMODEM How often has your modem disconnected when you were within the
last few bytes of a long, expensive file transfer? With ZCOMM's
ZMODEM file transfers, you can resume the transfer from where you were
cut off, without wasted time or phone charges! And, if the transfer
aborted because you ran out of disk space, ZMODEM can recover from
that too!
ZMODEM transfers files and commands with a uniquely user friendly
interface. Unlike traditional protocols, only one command or menu
choice is needed to transfer files or download commands.
(C) 1988 Omen Tech Inc Chapter 1 Introduction
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 3
"The Autodownload feature for ZMODEM (and KERMIT) has got me
completely addicted."
ZMODEM provides high throughput with full integrity even with
timesharing systems, high speed buffered modems, and packet switched
networks. Unlike other "high speed protocols", ZMODEM's high speed
does not compromise reliability. ZMODEM sets the throughput record
with 14 kilobit/second TrailBlazer modems tested at Telebit Corp.
LZW compression provides spectacular throughput increases on suitable
files.
A 32 bit Cyclic Redundancy Check, five orders of magnitude more
sensitive than CRC-16 and billions of times more sensitive than XMODEM
checksum protects your data.
Other features include text file translation, selective transfer of
updated files, remote file maintenance. Security authentication*
disables Trojan Horse attacks. ZMODEM supports today's operating
systems by preserving exact file contents and modification date, even
between time zones.
ZMODEM's speed and reliability have made it the protocol of choice
with progressive bulletin boards. ZMODEM is available now on many
bulletin boards and timesharing systems. Source code for
complementary Unix and VMS programs is provided in RZSZ.ARC.
1.4 XMODEM: The Lowest Common Denominator
ZCOMM supports the ubiquitous Ward Christensen "XMODEM" protocol with
Cybernetic Data Recovery(TM) and automatic file name generation. Omen
Technology's exclusive Cybernetic Data Recovery(TM) transfers files
under conditions that crash other programs.
+ XMODEM CRC-16 Even today, few commercial programs support 16 bit
CRC, the standard of XMODEM file transfer technology since 1981.
CRC-16 error detection is orders of magnitude more accurate than
checksum. Cybernetic Data Recovery(TM) catches and corrects
transmission errors that confound other programs.
+ True YMODEM(TM) batch file transfers preserve the exact file name,
file length and creation date.
+ XMODEM-1k and YMODEM-1k 1024 byte packets increase throughput with
bulletin boards, timesharing systems and networks.
(C) 1988 Omen Tech Inc Chapter 1 Introduction
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 4
1.5 Kermit: A Cure for Brain Damage
Kermit transfers ASCII and binary files with IBM, CDC, Cray, DEC, ICL,
Harris, Honeywell, Pr1me, Tandem, Univac and other mainframes that do
not support XMODEM.
ZCOMM's 16 bit Kermit CRC is thousands of times more sensitive to
errors than other programs' 6 bit checksum.
+ Convenient Kermit AutoDownload saves keystrokes, resolves Kermit
dialect incompatibilities that stymie other programs.
+ Sliding Windows Kermit speeds file transfers with timesharing
systems, satellite and packet networks. Also called SuperKermit,
it is the only high throughput download protocol available on The
Source(TM).
+ Kermit Long Packets speed file transfers with big IBM, CDC, and
Cray mainframe systems.
+ Advanced Kermit Server Access functions support low cost
networking.
1.6 Swiss Army Knife for Protocols
+ Extended Quick-B streaming protocol slashes CompuServe download
costs up to 60 per cent or more.
+ OverThruster(TM) Speeds XMODEM and YMODEM downloads
+ ZCOMM supports bulletin boards and traditional communications
programs with MODEM7 batch, Telink/FIDO, and Clink/SEAlink file
transfer protocols.
+ WXMODEM (Windowed XMODEM) speeds People-Link(TM) timesharing
service downloads.
1.7 X.PC: Your Own Packet Gateway
The X.PC network interface protocol flavor supports low level flow
control, error correction, multiple virtual calls and concurrent data
capture on one modem line.
1.8 Controlling Information
ZCOMM's Full-Time Capture Buffer(TM) lets you flip back and forth or
search, scanning two hundred messages from bulletin boards in a couple
of minutes. (It has to be seen to be believed.) To compose a reply,
call your favorite editor (the one you've already learned!) as a
subroutine without losing your place.
(C) 1988 Omen Tech Inc Chapter 1 Introduction
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 5
ZCOMM's high speed screen driver makes life pleasant:
+ Easy on the eyes: ZCOMM supports No Flicker displays, up to 450 per
cent faster than DOS
+ VT102, VT100, TTY 5425, ANSI, Z19, VT52, TI 940, IBM 3101, Televideo
9xx, and ADM3a emulation.
+ Supports 132 columns and advanced displays (114x60, etc.)
+ VT100 character graphics and keyboard mapping support "visual"
programs. Unlike Microsoft Access, Crosstalk, and most "VT100"
emulators, ZCOMM correctly displays EDT, AllIn1, and DEC Store on an
XT even at 19200 baud.
+ Hardcopy Terminal Emulation previews printer output by converting
overprint sequences to bold or underlined characters.
+ Visual (silent) bell preserves domestic tranquillity
+ Settable number of lines and columns, border color, default colors,
autowrap, keyboard mapping enable.
Full pathnames, directories, and wildcards support file transfers and
utility commands. Output may be redirected to printers or appended to
files. Files may be listed, paged, copied, renamed, searched, edited,
and deleted. Accuracy and identity of files transmitted by any means
are verified by word count and two types of checksum/CRC's. Matching
C Source code is available for many of these functions.
ZCOMM can search files for lines matching a string, insensitive to
case.
1.9 Transmitting Information
+ Dual stack Command Recall saves your keyboarded host commands in a
history file for search, recall, editing, and reentry.
+ Convenient Split Screen option allows responsive local editing of
input lines before transmission.
+ A rich palette of editing and timing modes permit file and message
upload, even to fussy microcomputer Bulletin Boards.
+ Remote access for file transfers and DOS program execution with baud
rate detection and three passworded security levels.
+ Outcall Queue intersperses scheduled outgoing calls with incoming
messages on one modem line.
(C) 1988 Omen Tech Inc Chapter 1 Introduction
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 6
1.10 Other Features
Interrupt driven modem input allows High speed operation with file
transfer and conversational terminal operation at 19200 bps and above.
One of 7 modem "ports" may be selected at any time.
A real-time status line displays column, row, time, elapsed time,
transmission speed, and other important information.
Soft keys provide convenient execution of common commands.
ZCOMM is written in C for performance, portability and
maintainability. ZCOMM loads quickly from a moderately sized
executable file with no cumbersome overlays.
Almost two decades of telecommunications knowledge are distilled in
ZCOMM.
(C) 1988 Omen Tech Inc Chapter 1 Registration
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 7
2. ZCOMM REGISTRATION
ZCOMM is a user supported program developed and supported by Chuck
Forsberg. ZCOMM is not and never has been public domain.
ZCOMM may not be modified, patched, hacked, disassembled, decompiled,
or otherwise reverse engineered, or sold, without prior written
permission by Omen Technology Inc.
The only legitimate way to disable the opening advertisement in ZCOMM
is to insert an authorized SNP obtained from Omen Technology into
ZCOMM with the putsnp program. Any other suppression or modification
of the opening screen is illegal, unethical, and prohibited.
Distribution of programs and/or instructions on how to modify, patch,
disassemble, decompile, or otherwise reverse engineer ZCOMM without
prior written permission by Omen Technology Inc is a theft of services
and a violation of federal copyright law, and will be referred to the
FBI for investigation and prosecution under federal conspiricy
statutes. Applicable RICO law provides for treble damages and
recovery of attorney's fees.
Distribution of ZCOMM in any medium without this documentation file
constitutes an unauthorized modification.
Individuals may use ZCOMM with only a moral obligation to register
their copy with Omen Technology. You may distribute the unmodified
ZCOMM*.ARC files to as many as you wish, or post them on bulletin
boards, etc. Businesses must register their copies of ZCOMM.
Registration buys you:
+ A clear conscience.
+ Your own unique ZCOMM Serial Number Password (ZSNP). Your ZSNP
may be applied to copies of ZCOMM to be run on a single machine.
+ Serialized of ZCOMM deactivates the registration request
display and the pause afterwards.
+ Serialization activates the egrep, egrepm, expand, split,
and ss commands and the outcall queue. Features denoted
with ** are available in serialized copies of ZCOMM.
+ Serialization more than doubles the circular buffer size.
+ A software disk with the current version of ZCOMM, the putsnp
program to serialize your copy of ZCOMM with your ZSNP, and the
tree structured "flash-up" help processor and help file included
in ZCOMMHLP.ARC.
(C) 1988 Omen Tech Inc Chapter 2 Registration
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 8
+ The complete Professional-YAM User Manual, 218 Typeset pages,
with many chapters not included here, ready for insertion into a
PC size binder.
+ The Pro-YAM Crib Sheet.
+ A ZCOMM registration is worth $40.00 when upgrading to
Professional-YAM. This upgrade includes the Pro-YAM software
disks and license. You will already have the manual from your
ZCOMM registration package.
REGISTRATION FEES:
+ Basic registration (ZSNP, disk, manual pages): $40.00
+ Custom Binder (OPTIONAL): $10.00
+ ONE of the following:
+ Domestic Shipping (UPS surface): $5.00
+ Domestic Surface Shipping: Free with prepaid orders
+ International Air Mail (most countries): $15.00[1]
+ Domestic UPS Second Day AIR: $5.00 additional
Don't bother scrounging for an envelope, use the INSTANT MAILER
included in this archive!
__________
1. $25.00 to Australia etc. if binder included due to higher cost.
(C) 1988 Omen Tech Inc Chapter 2 ZCOMM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 9
3. ZCOMM's Big Brother
ZCOMM is the Little Brother of Professional-YAM. As powerful as ZCOMM
is, more powerful than other user supported software, it pales beside
Omen Technology's commercial Professional-YAM software.
Pro-YAM's TurboDial(TM) script language provides state of the art real
time pattern recognition, "regular expiression" string parsing, script
development aids, script encryption, queue management, extensive
logging facilities, and finely tuned security control unmatched in the
industry.
Fortune 500 corporations use these exclusive features to support large
PC based telecommunications projects involving attended and unattended
operation.
Specialized utility commands allow Pro-YAM and a PC or DG/One portable
to replace data line monitors in many applications. Pro-YAM supports
Echoplex uploads and high speed data dumps in addition to the uniquely
accurate and robust XMODEM, YMODEM, ZMODEM, and Kermit protocol
transfers shared with ZCOMM. Pro-YAM has many powerful utility
commands that earn it the sobriquet Integrated Communications Tools.
Pro-YAM is available with the Tymnet X.PC link level protocol for
multiple, concurrent data transfers.
Omen Technology also markets highly compatible Unix and Xenix flavors
of Pro-YAM.
Omen Technology's Demand Upgrade(TM) technology and small company
responsiveness meet the support needs of a growing base of demanding
customers.
Professional-YAM is a superset of ZCOMM; applications and scripts
developed on ZCOMM will operate with Pro-YAM.
This ZCOMM manual omits descriptions of many Pro-YAM features not
included in ZCOMM. The special symbol * denotes Pro-YAM features not
included in ZCOMM.
Pro-YAM features not included in ZCOMM include X.PC, encryption,
CryptoScript(TM) capability, Password Guardian(TM), logs, the ap, apd,
bdump, fget, fput, kbdmon, link, obey, on, portx, purgek, quit,
restime, restrict, timestamp, trs, and usq commands, and certain
vertical application and security related features. (Newer versions
of ZCOMM include the logging facility.)
In some places you will see references to a fake Chapter 99. Pro-YAM
manual chapters not included in this document are designated by
Chapter 99.
(C) 1988 Omen Tech Inc Chapter 3 ZCOMM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 10
ZCOMM registration can be upgraded to Pro-YAM as described in the
previous chapter.
(C) 1988 Omen Tech Inc Chapter 3 Design Philosophy
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 11
4. DESIGN PHILOSOPHY
ZCOMM is a Communications Tool. Once learned, ZCOMM's command
interface is more powerful, faster, and less cumbersome than a menu
interface. Indeed, menus comprehensive enough to describe all the
nuances of ZCOMM's capabilities would take up more memory than most
microcomputers can afford. In addition, remote operation of ZCOMM
would be excruciatingly slow due to transmission delays displaying the
appropriate menu pages.
ZCOMM's look and feel has been influenced by the MODEM series of
programs, the Unix(TM) Operating System, the Berkeley Editor (vi),
CP/M(TM), PC-DOS, and ANSI standards.
Function keys F1 and F2 have been assigned with a logical grouping.
Wherever meaningful, F1 exits from a function, and F2 enters the
logical "next" function. From the command prompt, F2 enters the term
function, and from there another F2 enters the review function. Once
in the review function (assuming it was called from the term
function), F1 exits back to the term function, from where another F1
exits to the command prompt.
Another ethic guiding ZCOMM's design is respect for the user's
information. The user's data is, after all, precisely what a modem
program is all about. Status information is limited to one CRT line
to allow maximum screen size for data. Fancy display modes such as
reverse video are used sparingly to avoid distracting from the user's
work.
If you seek a video arcade modem game, ZCOMM will disappoint you.
4.1 Circular Buffer
The circular buffer remotely resembles the linear "capture buffer"
used by other modem programs. Many ZCOMM commands involve the
circular buffer, including the t, f, wait, ki, kill, w, review, and
close commands.
The term function uses the circular buffer as a first in, first out
(FIFO) buffer for data arriving from the remote. The circular
organization of this buffer makes the most recent data always
available for review and arbitrary writing to disk files.
When the circular buffer has been filled and the XOFF character sent
to the remote, ZCOMM writes the contents of the circular buffer to the
receive file if a receive file has been opened. ZCOMM then checks
whether any characters remain to be written to the printer. When both
of these checks are satisfied, ZCOMM then sends an XON character to
the remote to resume the transmission of data.
The ALT-W command or j mode can be used to write the contents of the
(C) 1988 Omen Tech Inc Chapter 4 Circular Buffer
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 12
circular buffer to the receive file without waiting for the circular
buffer to fill up first.
The large storage capacity of the circular buffer may be used to
review the most recent data received from the remote. The review
command allows one to page back and forth through the data received
from the remote. Forwards and backwards string searches make it easy
to locate important text. The review command also allows segments of
the data in the circular buffer to be selectively saved on disk (cut
and pasted). Scripts can search and mark text received from the
remote with the full power of regular expression pattern matching.
(C) 1988 Omen Tech Inc Chapter 4 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 13
5. ROSETTA STONE
Alphanumeric An alphanumeric character is either a letter or a decimal
digit 0 to 9.
Baud A baud is a signaling unit conveying one or more bits of
information. Baudrate is commonly (and usually incorrectly)
interchanged with bits per second.
BPS is an abbreviation for "bits per second", a measure of
transmission speed. ASCII Asynchronous transmission generally
uses 10 bits to transmit each character, so the speed in
characters per second is one tenth the speed measured in bits per
second.
Capture The term function captures data from the remote into the
circular buffer. This data may be paged back and forth with the
review function, or written to a disk file.
Character Escape is a sequence of characters initiated by a backslash
character used to represent a control character or programmable
string using printable characters. Character escapes are
described in Chapter 23.
CPMEOF A control character (hex 1A) added to the end of text files by
traditional microcomputer programs. This practice was popular
with the Digital Research CP/M 8 bit operating system.
Crash Recovery(TM) refers to the ZMODEM File Transfer Protocol's
ability to resume file transfers that have been interrupted by a
line disconnect from the point where the transfer was interrupted.
Cyclical Redundancy Check (CRC) is a datum (16 or 32 bits) generated
by a cyclic code. The CRC-16 extension to the Ward Christensen
XMODEM protocol provides a high level of data integrity. CRC-16
guarantees detection of all single and double bit errors, all
errors with an odd number of error bits, all burst errors of
length 16 or less, 99.9969% of all 17-bit error bursts, and
99.9984 per cent of all possible longer error bursts. The actual
performance is even better because the errors that sneak by CRC-16
are often detected by the other error checks simultaneously
applied by ZCOMM's Cybernetic Data Recovery(TM). ZMODEM's 32 bit
CRC provides five orders of magnitude more accurate error
detection than XMODEM's CRC-16 a billion times more accurate than
8 bit checksum used by standard XMODEM..
Download is the transfer of data from the remote system down to your
computer.
DTR is an abbreviation for Data Terminal Ready. Data Terminal Ready
is a signal sent by the computer to the modem to condition it to
(C) 1988 Omen Tech Inc Chapter 5 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 14
accept commands or answer an incoming call. When DTR is "dropped"
(switched off), the modem should disconnect from the line.
Execute When a string parameter is executed, it is normally sent to
the remote (modem). If it begins with "@", the remainder is
executed as a ZCOMM command.
Filespec Some ZCOMM commands instruct a remote Kermit server program
to send, receive, print, type, or delete one or more files. The
syntax of this specification is defined by the remote Kermit
server program, not ZCOMM. If filespec contains spaces, filespec
must be enclosed by double quotes.
Flow Control restrains the speed of transmission to prevent loss of
data when a fast sender must communicate with a slower receiver.
Hardware signals, control characters, and protocol handshakes can
be used to provide restraint, singly or in combinations.
SEE ALSO: handshake command, zmodem w parameter, Flow Control
Chapter 13
Functions are operations supported by ZCOMM, such as a dir, type, s,
r, or t (term) command. A command may set or reset mode[s],
change a parameter, or perform a function.
Host Operation allows remote access of files and programs.
Iff If and only if.
Integrity in a data transfer protocol refers to the ability of the
protocol to guarantee a correct data transfer provided both sender
and receiver report a successful transfer. Integrity is a
different measure of a file transfer protocol than robustness,
which is a measure of a protocol's ability to complete the
requested transfers in the presence of errors, independent of the
probability of undetected errors in the file transfer.
Kermit ia an error correcting batch file transfer protocol developed
at Columbia University and elsewhere. The Kermit protocol
supports text and binary file transfers with many mainframe
computers whose hardware and operating software preclude
implementation of high performance protocols. Kermit
implementations exist for many mainframes that cannot support the
XMODEM protocol.
Line Hit A burst of noise on a telephone line may generate modem data
errors. A single noise burst may garble dozens of characters.
ZCOMM's Error Containment(TM) technology may be used to reduce the
number of characters garbled by each line hit.
(C) 1988 Omen Tech Inc Chapter 5 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 15
Modes Many modes are available to modify the way the term function
receives, displays, transmits, and stores data.
Options Options apply to the Kermit, s, sx, sb, s7, st, r, rx, r7, rb,
and rc protocol file transfer commands.
q.v. Quod Vide is Latin for "which see", an invitation to consult
information on the subject mentioned.
Pathname is a complete file name, including disk and directories.
EXAMPLE: c:/ZCOMM/PHODIR.t
Pathspec ... A pathspec consists of zero or more pathnames.
Unambiguous and ambiguous (with wildcard characters) pathnames may
be specified in any combination. The wildcard filename characters
* and ? are allowed as described in the IBM DOS manual chapter
"Global Filename Characters". In DOS, only the filename portion
of the pathname may contain wildcards.
EXAMPLE: src/cmd/*.c is legal; src/*/foo.c is not.
On 32 bit Unix systems, ZCOMM expands "*" and "?" the way the
shell does. All the shell wildcards may be used including
multiple wildcards, wildcards in directories, and ranges. ~user
expands to the login directory of user, and ~ expands to your home
directory. In addition, `command` takes the output of command as
a series of pathnames.
EXAMPLE: dir */[a-i]* displays all files starting with "a" to "i"
in all subdirectories immediately below the current directory.
An empty pathspec represents all files in the current directory on
the current disk. A disk identifier without any file names
represents all files on that disk's current directory. A
directory pathname expands to all files in the specified
directory.
Sequences of the form %svar are replaced by the value (possibly
empty) of the string parameter svar. If svar is not a string
parameter, no substitution is made.
A pathspec may contain any combination of the above, separated by
spaces or tabs.
If pathspec includes a disk specifier (such as a: or b:), ZCOMM
checks the disk specifier against the list of permissible disk
(C) 1988 Omen Tech Inc Chapter 5 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 16
specifiers in the string parameter disks.
The various filename expansions are especially useful in the
context of commands such as wc, sum, chek, crc, find, sb, and sz.
For example, wc applies to all files in the current directory, and
wc dir applies to all files in dir.
ZCOMM pathnames may use / or \ to delimit directories.
Regular Expressions control pattern matching and grouping of text by
the ss and egrep commands. "Magic" characters specify the pattern
matching and grouping processes.
Remote refers to the machine or terminal with which ZCOMM is
communicating. This could be a direct RS-232 connection to a
local terminal, micro, mini, or mainframe, or a timesharing system
accessed through a modem and a global packet switched network.
Restraint See "Flow Control" above.
Restricted For security reasons, ZCOMM is restricted to prevent
unauthorized dial-in users from accessing private data or crashing
the system. Certain commands are illegal when ZCOMM is
restricted, and only specified disk drives and directories may be
accessed.
Review Function The last 32k characters of output from the remote may
be paged and searched online with the review function. This data
may also be cut and pasted to disk files.
Robustness in a file transfer protocol refers to the protocol's
ability to complete transfers in the presence of errors induced by
line noise or other sources. Robustness is a different measure of
a file transfer protocol than integrity, a measure of the
probability of correct data transfer given a successful completion
of the transfer process.
Script A script is a set of commands that control dialogues with the
user or a remote system.
Script Level refers to the degree of nesting of scripts. Level 0 is
called by the user directly, and each higher level is executed by
a gosub or other command from the previous level.
Shell Escape is a DOS command or program called as a subroutine from
ZCOMM via a DOS Gateway. The phrase "shell escape" comes from the
Unix(TM) Operating System, whose command interpreter is called
"the shell".
Soft Keys Strings or commands may be assigned to the Soft Keys with
set commands, including those in the telephone directory "setup"
(C) 1988 Omen Tech Inc Chapter 5 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 17
entry executed each time ZCOMM starts. ZCOMM recognizes the forty
function key codes produced by the function keys F1 to F12. FS1
to FS12 are obtained with a Shift key, FC1 to FC12 are obtained
with the Ctrl key, and FA1 to FA12 are obtained with the Alt key.
The cursor keys and extra function keys on 101 key Extended
Keyboards are also recognized.
Strings or commands may be assigned to BS, ESC, Ins, Del, Home,
End, Up, Down, Left, Right, PgUp, and PgDn, overriding their
normal functions in the term function.
String Some commands take a string argument. If a string argument
contains spaces, tabs, and a semicolon, it must be enclosed by
double quotes (shift single quote on the IBM PC keyboard).
Control characters may be included in strings with character
escapes similar to those used by the C Programming Language.
Term Function ZCOMM's Term Function provides the conversational
"connection" between the user and the remote. The term function
captures data from the remote into ZCOMM's circular buffer from
whence it may be displayed, printed, stored in a disk file, or
searched, cut and pasted by the review function.
TWX Teletypewriter Exchange (Teletype Corp. TM). A simple protocol
used to transmit files or paper tapes between dial-up
teleprinters.
Upload is a transfer of data from your computer up to the remote
system.
Wild Card Many commands allow wild card file names in their pathspec
(q.v.).
Writing When a receive file is open as a result of a create or t
filename command, data in the circular buffer is written out to
the receive file when the circular buffer fills up or when a w or
ALT-W command is given.
XMODEM The Ward Christensen file transfer protocol uses 128 byte
packets, one byte control messages, and a one byte arithmetic
checksum.
XMODEM/CRC A synonym for the enhanced Ward Christensen XMODEM protocol
using a Cyclic Redundancy Check (CRC-16). Newer programs support
CRC-16 for better data integrity, but reliability is still
compromised by one byte control messages.
XMODEM-1k XMODEM protocol with 1024 byte data packets, CRC-16, and one
byte control messages, sometimes incorrectly called ymodem.
(C) 1988 Omen Tech Inc Chapter 5 Rosetta Stone
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 18
YMODEM YMODEM is a batch file transfer protocol with pathname, date,
file length and other file data in block 0, CRC-16 default, and
optional 1024 byte packets. Many programs claiming to support
YMODEM actually use XMODEM with 1024 byte blocks; use ZCOMM's sx
-k and rx commands with these XMODEM mutants.
XOFF, XON ASCII control characters control the flow of data. XOFF
(Ctrl-S) stops and XON (Ctrl-Q) resumes the flow of data. Chapter
29 provides an ASCII code chart with the names for the control
characters.
ZCOMM is a shareware (User Supported) subset of Professional-YAM.
ZMODEM An advanced public domain file transfer protocol with
simplified human interface, crash recovery, high speed streaming,
sensitive 32 bit CRC, command download, security features, and
important file management functions.
{arg1 | arg2} One of the arguments separated by | is required.
[] Optional argument.
* The special symbol * denotes features not included in ZCOMM. **
Denotes features not included in userialized (unregistered) copies
of ZCOMM.
(C) 1988 Omen Tech Inc Chapter 5 Installing ZCOMM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 19
6. INSTALLING ZCOMM
If you have registered your copy of ZCOMM, make yourself a working
copy of the ZCOMM distribution disk using the DOS diskcopy command to
make exact copies. Keep the distribution disk in a safe place away
from nasty data killers such as disk drives, displays, computers,
magnets, motors, and coffee cups. The only time the distribution
diskette should be out and about is when you are cloning your working
copies.
6.1 Installation from Registration Disk
The putsnp program inserts your ZCOMM Serial-Number-Password (ZSNP)
into your working copiy of ZCOMM. Installing a legal serial number
suppresses the pause after the opening message, enlarges the circular
buffer, and enables new commands. The putsnp program prompts for your
Serial/Number/Password (SNP) of the form X123456789. Putsnp checks
for keyboarding mistakes and then verifies that you understand and
agree to the licensing conditions. When you understand and agree to
the licensing conditions, respond with yes (not just y).
Then putsnp prompts for the name of a file to insert the serial number
into. This should be a ZCOMM.EXE file that you have transferred to a
scratch disk, or to an appropriate directory on your hard disk. Do
not write on the distribution diskette unless a nuclear attack is in
progress.
After inserting the serial number in the given file, putsnp asks if
you wish to change the default value for the phone directory pathname
(string parameter phones). This is normally /PHODIR.t. If you wish
to keep the phones file elsewhere, answer "yes".[1] Putsnp then
searches for the location in your copy of ZCOMM that contains this
information. When found, you may enter a new pathname,[2] up to 64
characters.
Afterwards, you should copy the help processor files YHP.EXE and
ZMANH.HLP from the disk.
__________
1. The default value may also be overidden with the PHONES DOS
environment variable.
2. Such as c:/zcomm/PHODIR.t.
(C) 1988 Omen Tech Inc Chapter 6 Installing ZCOMM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 20
6.2 Installation from ZCOMM*.ARC
If you are using the software provided in ZCOMM*.ARC, be sure to save
the original files for backup, and pass them on to your friends to
fill their communications needs. There are currently three ZCOMM
archive files:
+ ZCOMMEXE.ARC contains the executable program and demonstration
files.
+ ZCOMMDOC.ARC contains this documentation.
+ ZCOMMHLP.ARC contains ZCOMM's tree structured help file and random
access flash-up help processor.
6.3 Installation Continued
The second order of business is to read this manual. There is just no
way you can get your money's worth out of ZCOMM without reading, or at
least carefully scanning, this manual. After all, didn't you get
ZCOMM because you needed something more powerful than that cumbersome,
unreliable, brain-damaged menu driven crock you've been using?
(Perhaps you shouldn't answer that question just yet ...)
You can then edit PHODIR.t to suit your own needs by inserting
directory entries for the systems you wish to call and changing the
phone numbers, account numbers, and passwords on the "standard"
entries for popular timesharing services that you have accounts with.
Be sure to check the setup entry and make any changes you feel
appropriate. Once you have the "feel" of ZCOMM, you will want to
remove the automatic menu invocation at the end of the setup directory
entry.
Chapter 9 gives a line by line tutorial for setting up your telephone
directory assuming you are using a standard modem.
If you are using a computer that runs at non standard clock rates
(e.g., 8 mHz 8088 instead of 4.77 mHz) or with an enhanced CPU chip
(NEC V20), you will need to set special values for the a and b numeric
parameters as described in Chapter 21.
**** WARNING **** Although ZCOMM is well behaved as communications
programs go, some memory resident programs, special keyboard
modifiers, print spoolers, or special display drivers, may cause
problems. The POLYTRON memory-resident desktop organizer PolyWindows
DeskPlus as well as POLYBoost work with ZCOMM.
**** WARNING **** Since ZCOMM uses interrupts to read data from the
(C) 1988 Omen Tech Inc Chapter 6 Installing ZCOMM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 21
serial ports, each serial port must be strapped for its proper
interrupt vector. Some communications programs assign both IRQ3 and
IRQ4 while operating, so they will operate even if the serial ports
are not strapped properly. Since ZCOMM only assigns the interrupt
vector of the port in use, incorrect IRQ level strapping will crash
ZCOMM. Check the serial port addresses and vectors with the
information given ith the port command in Chapter 15 if you encounter
trouble starting ZCOMM.
(C) 1988 Omen Tech Inc Chapter 6 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 22
7. TAMING THE MODEM
7.1 Hardware Interface
DOS ZCOMM accesses serial ports at the standard COM1 and COM2 address,
as well as COM3-COM7 as described with the port command. The portx
command may be used to access non standard 8250 port addresses.
When a port is selected, a quick hardware check is made to verify the
existience and minimal functionality of the port. If this test fails,
the message Port N Defective is displayed. An incorrect port switch
or strap (jumper) configuration is the usual cause of this message.
This check does not guarantee the port is connected to the proper IRQ
line. If the port is not configured to use the proper IRQ line, the
computer may lock up when the port is used.
Some 8250 UART devices (used by serial interface adapters and internal
modems) do not respond correctly when the software turns the
transmitter interrupts on and off. High performance communications
programs such as ZCOMM require properly functioning UART chips, such
as the National Semiconductor 16450 or 16550A.
7.2 Carnival of the MODEMS
Modem manufacturers are constantly refining their products and adding
subtle new features. To obtain the full performance your modem
provides, you can edit initialization strings in the dialing scripts
to take advantage of new modem features as they are developed. For
example, changing the X1 string sent by the dialing script to X2,X3 or
X4 enables extra features on some modems. Some modems do not emulate
the Hayes Xn commands exactly, requiring a change to the Xn value
emitted by the dialing script for proper operation. The line in mm224
to modify is:
if !%MODEM put "ATX3\r"; wait -f2 :: Change this for your modem
If your modem is not listed in one of the following subchapters,
please read all the subchapters and use the suggestions that apply to
modems similar to yours.
7.3 Tone Dialing
If your telephone line supports Tone Dialing, set mprefix to ATDT with
a command in the setup telephone directory entry. If your telephone
line only supports rotary (pulse) dialing, set mprefix to ATDP. This
procedure is detailed in Chapter 0u.
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 23
7.4 MNP, X.PC, LAPB, AFT
Some modems are available with one or more error correcting link level
protocols such as MNP. Sometimes enabling MNP in a modem impairs
logging into timesharing systems, packet switched networks, or
bulletin boards. In addition, non streaming protocols such as XMODEM,
YMODEM, Kermit and Compuserve B give faster transfers without the
delays introduced by MNP and other link level protocols. Accordingly,
ZCOMM's dialing scripts are designed to place calls with MNP disabled
by default.
The mm224 dialing script allows an optional link level modifier to be
appended to each telephone number.
The currently supported modifiers are:
/300 Force a connection at 300 bps. Dropping down to 300 bps may
be necessary to get a reliable connection in Oregon.
/1200 Force a connection at 1200 bps.
/nop Suppress the detection of call progress reporting. This may
be used to prevent the modem from misinterpreting an unusual
ringing sound as a busy signal.
/fast Force a high speed connection (refuse a slow speed
connection).
EXAMPLE: 123-4567/fast
mnp Require MNP link level connection. Do not connect if MNP
fails.
EXAMPLE: 123-4567/mnp
/mnp_s Require MNP link level connection, use software flow control.
Do not connect if MNP fails.
/a_mnp Request MNP link level connection.
/a_mnp_s Request MNP link level connection, use software flow control.
/xmodem Enable "XMODEM spoofing" on Trailblazer modems.
/kermit Enable "Kermit spoofing" on Trailblazer modems.
NOTE: Most modems do not support all these modifiers.
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 24
7.5 MODEM environment variable
The mm224 dialing routine uses the MODEM environment variable to
indicate the type of modem it is driving. Except for ZCOMM, the value
inherited from the environment may be overridden with a set command.
Currently supported values for MODEM are:
MM224 MultiModem 224 without MNP. This works with many other 2400
bps modems with little or no modification.
MM224E MultiModem 224E with MNP.
SM1200 Hayes SmartModem 1200
HV96 Hayes V series Smartmodem 9600
TB Telebit TrialBlazer
Note: these values are all upper case.
7.6 High Speed Modems
The new generation of high speed dial-up modems presents special
oppurtunities and challenges to users and system integrators.
These modems transmit data at speeds from 110 to 38400 or more bits
per second. This range of speeds poses special problems communicating
between the computer and the modem. Lower speed modems examine the
traditional "AT" command prefix bit by bit to lock onto the computer's
transmission speed instantly. Many modems which recognize commands at
widely varying speeds can not use this technique. A number of
alternate techniques have been developed, each with its own advantages
and problems.
+ Lock the interface to the highest tranmsission rate. This aviods
the programming required to synchronize the modem's and computer's
speeds. Flow control must be used when the interface speed is
locked to prevent the computer from sending data more rapidly than
the modem can buffer and transmit it. This local flow control is
usually accomplished with hardware signals. When such an
arrangement is used to communicate over networks that must assert
their own flow control (with XON and XOFF), data flow regulation
must respond to both hardware (RTS) and software (XOFF) signals.
The handshake both command should be used whenever the modem's
interface speed is locked and transmission over networks or to
timesharing systems is desired.
When the interface speed is locked at a higher speed than the
actual data transmission, an excessive amount of data may be
stored in the modem's memory awaiting transmission. This is
inefficient when a streaming file transfer protocol is used
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
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ZCOMM User Manual 25
because the data backed up in the buffer must be drained before
error recovery can commence. The ZMODEM b and w muneric
parameters should be used to manage the modem's data storage.
Locking the interface speed to 9600 or 19200 bps while
communicating at 1200 and 2400 bps should be avoided unless all
links in the transmission path have low error rates.
Most modems do not recognize XOFF characters from the remote
computer, so characters stored in the modem's buffer will be
transmitted for a period of time after an XOFF is received. This
causes loss of data with some computer services.
+ Autobaud to adjust the modem and computer speed. With this
method, the modem is optioned to enter a search mode whenever it
becomes idle. The dialing script calls the waketb phone directory
subroutine to train the modem to the computer's transmission
speed. The waketb subroutine may be optimized for the particular
modem used.
After dialing or answering a call, the modem handshakes with the
remote modem and reports the connect speed with a message such as
"CONNECT 1200" or "CONNECT FAST". The dialing script recognizes
the string, and sets the computer to the correct speed. If the
connection is made at high speed, the dialing script may need to
enable hardware flow control with a handshake command.
7.7 TELEBIT TrailBlazer
The Telebit TrailBlazer modem uses 68000 and TMS320 processors to
transmit serial data at rates up to 14000 bps over standard phone
lines. The modems also operate at speeds of 2400, 1200, 300 and
slower. The TrailBlazer is one of the most complex modems to fully
exploit, a worthy challenge for a TurboDialTm script. Use the mm224
dialing routine discussed above for this modem. The mm224 dial
routine has special provisions to exploit this modem's features. Set
the MODEM environment variable to TB (caps are important) to support
the TrailBlazer's MNP, speed and flow control features.
Before making calls, use the inittb phone entry to initialize the
modem's non volatile memory with proper settings for ZCOMM.
EXAMPLE: call inittb
ZMODEM provides optimum file transfer speeds with these modems.
ZMODEM avoids interference with the modem's flow control.
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 26
7.8 MultiTech MultiModem 224E
Special features of this modem are accessed with the mm224 dial
script. Set the MODEM environment variable to MM224E (caps are
important) to support the MM224E's MNP, speed and flow control
features.
Set dip switch 1 on the bottom of the modem to up (DTR Normal), the
reverse of the factory setting. For high speed operation, CTS flow
control should be enabled with internal switches and jumpers.
Before making calls, use the initmm phone entry[1] to initialize the
modem's non volatile memory with proper settings for ZCOMM.
EXAMPLE: call initmm
This disables automatic error correction under mnp. If you wish to
enable this setting, merely type, from the terminal mode, 'at &e0 &w',
and the 'ok' which will ensue tells you that the command was accepted
and stored in non-volatile memory.
7.9 MultiTech MultiModem 224
The autobaud feature of this and most other 2400 bps modems is
accessed with the mm224 dial script. This dialing script is the
default choice in the distribution phones.t file. Set the MODEM
environment variable to MM224 (caps are important) to support the
MM224.
7.10 Hayes Smartmodem V9600
This modem should be initialized with the inithv96 entry in the
telephone directory. The AFT link level is enabled by default because
it does not appear to interfere with connections to modems not
supporting AFT.
7.11 Hayes Smartmodem 2400
The Hayes Smartmodem 2400 presents the same same considerations as the
Smartmodem 1200 described below. Unlike the 1200, the 2400 uses a non
volatile memory to store configuration parameters instead of the
switches used in earlier models. The sequence AT&C1 &D2 &R1 &S1 &T5
&W should be sent to the modem to set normal operation for DCD, DTR,
CTS, and DSR. The T5 command disables remote loopback request, a
__________
1. Information courtesy Earle Robinson
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
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ZCOMM User Manual 27
source of failed file transfers on noisy lines. Finally, the &W
command writes this information to the non volatile memory. Please
consult your Hayes manual for more information on these commands.
7.12 Hayes Smartmodem 1200
The Smartmodem 1200 and similar 1200 bps modems are compatible with
the mm224 telephone directory entry. Some modems may require a change
in the X1 command to a higher Xn digit for proper autobaud operation.
The Smartmodem 1200(TM) should be configured as follows by setting
S1-S8, located under the front panel. These switches may be accessed
by gently prying the ears of the front bezel, allowing the bezel to
pop off the front of the unit.
S1 Up Support DTR Lead
S2 Up Verbal result codes (Verbose) [2]
S3 Down Result codes are sent
S4 Up Echoes characters in command state
S5 Down Modem does not answer calls initially
S6 Up Carrier Detect line reads status
S7 ???? See Hayes manual
S8 Down Enables Smartmodem 1200 command recognition
The modem cable should connect the following RS-232 circuits: AA BA BB
AB CF CD which use pins 1,2,3,7,8, and 20 on the Hayes modem. Some
programs require pins 5 and 6 connected to the modem.
NOTE: Some Hayes modems require mprefix to be in upper case only.
"Hayes Compatible" modems not manufactured by Hayes generally work
with the same mprefix, but some of the other modem control strings
that appear in the distributed PHODIR.t file may not work properly
with a particular brand of modem.
7.13 Microcom AX9624c
Microcom AX modems have a configuration switch to select Hayes style
"AT" commands. The AX/9624c front dip switch should be set 1, 4, 6, 7
UP, 2, 3, 5, 8 DOWN, and A/S OUT (asynchronous). The rear switches
are all UP. Of all these switches, it is vital that front switch 2 be
DOWN (AT commands) and rear switch 6 be UP; the initax9624 script
should override the others.
__________
2. If other options are necessary (to support other software) a
custom dial routine may be used as described in Chapter 99.
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 28
Set the MODEM environment variable to AX9624 (caps are important) to
support the Microcom AX9624's MNP and flow control features. Before
making calls, use the initax9624 phone entry to initialize the modem's
non volatile memory with proper settings for ZCOMM.
EXAMPLE: call initax9624
7.14 Microcom SX Series
Older Microcom SX series modems have a unique command set incompatible
with Hayes modems. Furthermore, careful attention must be paid to
flow control issues to obtain reliable operation. When using XMODEM
or other protocols, the modem must be set to pass all 8 bits and all
256 code combinations of those 8 bits. The dialsx script sets the
modem to "transparent software flow control" as described in Chapter
13. Change the line
set mcommand "gosub dial"
to
set mcommand "gosub dialsx"
in the setup telephone directory entry.
7.15 Novation Access 1-2-3
The modem prefix should be set to "%D I". When initializing, the
modem should be set to 8 bit data mode with a putw "%F 4\r" [3]
command. The phones2.t file should be used as a basis for your
phones.t file if this is your main modem.
The Novation modem must be explicitly commanded to change speed with a
"call 1200" or "call 300".
Some modems may latch up if they are disturbed while dialing. The
modems may have difficulty recognizing dial tone. A Novation "W"
command may be used to force a wait and bypass listening for the dial
tone. "W" command(s) after the phone number also be useful when
attempting to handshake with V.22bis (2400 bps) modems. A custom
"dial" script can also be used to manage the peculiarities of these
modems.
Users of the PC-jr Smartcat(TM) or similar modems should set mprefix
to "\16 D " to provide the necessary command sequence for dialing.
Many of the Novation Smartcat considerations discussed above apply to
__________
3. See Chapter 23 for a description of character escapes.
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 29
the PC-jr version.
7.16 Prometheus ProModem 1200
The following switch setting works with ZCOMM: 1-4,6,9 on; 5,7,8,10
off.[4] A custom "dial" script can be written to operate this modem in
its native mode.
7.17 Racal-Vadic Maxwell 2400V
The Maxwell 2400V has long delays designed to allow switching between
data and voice operation on the same phone line. Unfortunately, they
slow normal data operations. The 2400VP reportedly does not have this
feature.
Use the default mm224 dialing routine discussed above for this modem.
7.18 Standard 103/212
The supplied "dial" script will present the number to the user and
wait for a success/fail response if the mprefix string parameter is
set empty. Alternatively, one could change the script to loop waiting
for carrier detect while the keyboard is inactive. The Data Set Ready
(DSR) signal may be connected to the modem's speed detect output (high
for 1200 bps, low for 300) allowing the dr test condition to sample
the DSR line to determine the speed of the incoming call.
7.19 Data Race BMX
These modems have a switch selected interface speed, an AT style
command set, and switch options for software or hardware flow control.
Recommended settings are: AT commands, Dialup, 8 bit data (down),
disable XON (7 and 8 down), Echo on. ZCOMM's handshake on command
should be used.
__________
4. Prometheus mode does not work with ZCOMM's built-in dialing
software because the "DIAL COMPLETED" message makes ZCOMM think
it's seen "CONNECT" (ZCOMM looks for a "T").
(C) 1988 Omen Tech Inc Chapter 7 Taming the MODEM
Version 17.32 TurboDial 2.33 Universal Line Printer Edition
ZCOMM User Manual 30
7.20 Strange Modems
Most intelligent modems can be commanded to autodial with a suitable
mprefix and msuffix string. Those modems that won't work with a
particular mprefix can be programmed with a custom "dial" script. If
the modem can be configured to reset to a known condition when DTR is
turned off, programming is usually straightforward.
Otherwise, the script must determine what speed the modem is set to,
and then, at its present speed, command the modem to change to the
desired speed. The essential requirement is to write a script that
controls the modem and responds to its state. The information on
scripts in Chapter 99 should prove useful.
7.21 Manual Dialing with Smart Modems
Some hotels and exotic locales sport telephone systems with unusual
dialing requirements. It may be necessary to dial the call with the
telephone, talk to an operator, and then activate the modem. With
Hayes compatible modems, an ATD command may be given to the modem to
connect it to the line and attempt a data handshake.
7.22 Direct Connection
ZCOMM works well communicating with locally connected microcomputers,
minicomputers, or mainframes with direct RS-232 connections. For such
applications, only transmit and receive data data signals need be
connected to the computer. The Carrier Detect line[5] should be
driven ON (+5 volts) to prevent noise on this signal by strapping it
to Data Terminal Ready [6] if no other signal is available.
For best high speed operation, replace 8250 or 16450 UART chips with
the NS16550AN chip. ZCOMM enables the hardware buffering on this chip
to avoid data loss caused by TSR programs, special device drivers,
extended memory disks or caches, and DOS clock interrupts.
__________
5. Pin 8 on 25 pin RS-232 connector, pin 1 on PC-AT 9 pin connector.
6. Pin 20 on RS-232 connector, pin 4 on PC-AT 9 pin connector.
(C) 1988 Omen Tech Inc Chapter 7 Your Telephone Directory