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1. INTRODUCTION.................................................. 2

2. PROTOCOL FILE TRANSFERS....................................... 3
2.1 Graphic File Transfer Display........................... 3
2.2 Choosing the Best Protocol.............................. 4
2.3 ZMODEM-90(TM)........................................... 4
2.4 Sending files with ZMODEM............................... 6
2.4.1 File Maintenance with ZMODEM.................... 6
2.4.2 MobyTurbo Accelerator........................... 6
2.4.3 ZMODEM Compression.............................. 6
2.5 Receiving files with ZMODEM............................. 7
2.5.1 ZMODEM AutoDownload............................. 7
2.6 Tuning ZMODEM Parameters................................ 7
2.6.1 Receiver Window Size Override................... 8
2.6.2 Terminal Multiplexers........................... 8
2.6.3 7 Bit Environments.............................. 8
2.6.4 Manual ABORT.................................... 8
2.7 XMODEM Family Protocols................................. 9
2.7.1 TRUE YMODEM(TM)................................. 9
2.7.2 YMODEM-1k....................................... 9
2.7.3 YMODEM with OverThruster........................ 9
2.7.4 XMODEM-1k....................................... 10
2.7.5 XMODEM-CRC (with fallback)...................... 10
2.7.6 Classic XMODEM.................................. 10
2.7.7 Relaxed XMODEM.................................. 11
2.7.8 XMODEM with OverThruster........................ 11
2.7.9 YMODEM-g: Traditional Overdrive................. 11
2.7.10 XMODEM Mutants Misrepresented as YMODEM......... 12
2.7.11 Qmodem-G/Streaming XMODEM....................... 12
2.8 Transferring Files with Unix Systems.................... 13
2.8.1 Uploading Files to Unix Systems................. 13
2.8.2 Downloading Files from Unix Systems............. 14
2.9 VAX/VMS File Transfers.................................. 15
2.9.1 Version 4 rz/sz................................. 15
2.10 GEnie File Transfers.................................... 16
2.11 BIX File Transfers...................................... 16

3. FLOW CONTROL.................................................. 18

4. SELECTED COMMANDS............................................. 21

5. Protocol File Transfer OPTIONS................................ 29

6. NUMERIC PARAMETERS............................................ 37
6.1 X/Y/ZMODEM Numeric Parameters........................... 37

7. HARDWARE/SOFTWARE COMPATIBILITY............................... 41
7.1 Hardware Compatibility Notes............................ 41
7.2 Brain Damaged UARTS..................................... 42
7.3 Software Compatibility.................................. 43

8. CROSS REFERENCE INDEX......................................... 48

Chuck Forsberg

DSZ Manual Addendum
(Selected Pieces of the Pro-YAM Manual)

Formatted 11-3-92

For DSZ Users ONLY
For DSZ Users ONLY
For DSZ Users ONLY
For DSZ Users ONLY

Cybernetic Data Recovery(TM)

Universal Line Printer Edition

Copyright 1992 Omen Technology Incorporated
All Rights Reserved

Omen Technology Incorporated

The High Reliability Software

17505-V Northwest Sauvie Island Road
Portland Oregon 97231
VOICE: 503-621-3406 :VOICE
Modem: 503-621-3746 Speed 1200,2400,9600
Compuserve:70007,2304 GEnie:CAF
UUCP: ...!tektronix!reed!omen!caf

(C) 1990 Omen Tech Inc Chapter 0

DSZ Manual Addendum Line Printer Draft


The chapters included here are taken from the Pro-YAM manual. Some of
the features described here do not apply to DSZ.

DSZ does not support ZMODEM Command Download, ZMODEM Security Check,
Kermit and certain traditional protocols (WXMODEM, *LINK, MODEM7,

When DSZ is called from a bulletin board or other communications
program, automatic ZMODEM file download is not available. ZMODEM
AutoDownload is available from DSZ's t command (talk/term function).

EXAMPLE: dsz port 1 speed 2400 t -8g

Chapter numbers refer to chapters in the ZCOMM user's manual.

Welcome to the Rain Forest

(_) /~\\
/~\\ / \\/\\
/ \\ /\\ / | \\ \\
/\\ / \\ \\/ /|\\ \\ \\
/ \\ / \\ / //|\\\\ \\ \\
_/_ \\_/ ___ \\ ///|\\\\\\ _\\_\\
_________________ _______ | ________

-A Usenet Signature

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Protocol File Transfers 3


2.1 Graphic File Transfer Display

# Professional-YAM Copyright 1991 Omen Technology INC #**
# #**
# #**
# File pcmagc.dmp 1 of 5 #**
# #**
# Current 43520 of 43520 Total 43520 of 999879 #**
# #**
# This ################################################## #**
# 0------------------------50------------------------100% #**
# Total ##- #**
# Throughput 8704 Retries 0 Time left 2 min #**
# Connect ET 13:09 Time 13:18 Modem status #**
# #**
# #**
# Subpkt LEN 512 Window SIZ #**
# ALT-F Cancel File ALT-B Cancel Batch #**
# #**

38kbps batch file download from a Unix system.[1] ZMODEM-90(TM)
compression yields 87kbps effective speed on the PC Magazine
Compressible File benchmark.[2]

GSZ, ZCOMM and gYAM feature a full screen graphics status display of
file transfer statistics. The amount of information displayed depends
on the protocol and sending program. XMODEM, CompuServe B+, and
Kermit download displays use information supplied to the estimate
command. In the absence of a user specified throughput value, Time
left is calculated with real time data. Real time throughput may be


1. Pto-YAM screen snapshot made with ALT-Z. The resultant YAMPIC
file was renamed to YAMPIC.BIN and read in to THEDRAW. Thedraw
output the screen contents in IBM ANSI format, which was then
typed and screen dumped to Postsctipt with SCRtoPS(TM) by Olfe

2. Page 159, April 30 1991 PC Magazine.

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4 Protocol File Transfers

inflated for the first 5-20 kilobytes when a streaming protocol sends

On PCDOS YAM flavors, call (connect) elapsed time, time of day, and
MODEM status are displayed. MODEM status is displayed as follows:

x Software flow restraint (XOFF)

X Hardware flow restraint (CTS, etc.)

L Loss of Carrier Detect signal (CD)

H On Hook (DTR off)

2.2 Choosing the Best Protocol

A file transfer protocol should have high integrity (assurance of
accurate data) and high robustness (low probability of aborting a
transfer). And, it should be as fast as possible without compromising

When PC Magazine tested file transfer protocols in early 1991, they
ignored the file transfer recommendations given in this manual. Their
ignorance slowed Pro-YAM file transfers by as much as 400 per cent.

With many different ways to transfer files, your choice of file
transfer methods can make the difference between efficient, error free
data and slow or error prone transfers.

The following subchapters discuss file transfer methods in more

2.3 ZMODEM-90(TM)

ZMODEM was developed in 1986 for the public domain (PD) under contract
by Telenet, a major packet switched network. Omen Technology's
commitment to file transfer technology did not stop with PD ZMODEM.
ZMODEM-90(TM) is Omen Technology's copyrighted refinement of PD
ZMODEM. ZMODEM-90 speeds transfers with COMPRESSION and other
accelerators. ZMODEM-90 adds frame types to support transfers in 7-
bit environments. ZMODEM-90 sends files faster and more reliably than
PD ZMODEM. Omen Technology's ZMODEM-90 transfers files accurately in
many applications where other ZMODEM programs abort or corrupt data.

ZMODEM provides a greatly simplified user interface. The file name is
entered once, and transfer options may be given to the sending
program, even those that apply to the receiver. ZMODEM
AutoDownload(TM) allows menu and mouse driven programs to download
files and commands with no extra keyboarding required.

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ZMODEM transfers one or more files with a single command. The size
and transfer time for each file is displayed, and the total number of
files, size, and transmission time is displayed when more than one
file remains to be sent on a command.

Keyboarding ALT-F allows the receiver to bypass an individual file
without having to restart the batch.

ZMODEM transfers both files and commands. Command download allows one
of the computers to take positive control of the session. A security
challenge (activated by ZMODEM AutoDownload(TM)) guards against Trojan
Horse messages.*

ZMODEM file transfers can preserve the file date and the exact file
contents, unlike traditional protocols that append garbage to files.

Streaming transmission provides full throughput over satellite links
and packet switched networks. One of three ZMODEM streaming control
methods may be used with systems that allow the sender to monitor the
received data for error correction packets without interrupting
transmission. ZMODEM's "block length" is the entire file!
Individually acknowledged packets support other systems.

ZMODEM allows programs to adjust the protocol parameters for optimum
efficiency as the file is being sent. ZMODEM-90 allows programs to
adjust character encoding for best results with a variety of systems.

ZMODEM is immune to conditions that prevent reliable, accurate file
transfers with traditional protocols:

+ ZMODEM data transfers are protected by the Federal Standard 32 bit
CRC to assure reliable transfers. This 32 bit CRC gives an
undetected error rate five orders of magnitude better than XMODEM's
16 bit CRC, and more than a billion times better than checksum
XMODEM. ZMODEM uses 16 bit CRC for file transfers with programs
that do not support 32 bit CRC.

+ Most important, all ZMODEM protocol transactions are protected by
CRC. Other protocols advertising 16 or 32 bit CRC sometimes fail
under stress because critical control messages are not CRC

If you've ever been disconnected when a huge file transfer was almost
finished, you'll appreciate resuming/recovering the file transfer with
ZMODEM Crash Recovery Omen Technology Incorporated's Intelligent Crash
Recovery(TM) guards against file corruption during Crash Recovery
operations. (ZMODEM r and rr options.)

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6 Protocol File Transfers

2.4 Sending files with ZMODEM

To send a file with ZMODEM, the command sz file1 can be given from
either the main command prompt, or from the term function via a
secondary command prompt obtained with ALT-2. Multiple files and wild
cards may be used.

EXAMPLE: sz file1 file2 *.lst

Please refer to the sz and zcommand commands in Chapter 19 for more
examples and information.

2.4.1 File Maintenance with ZMODEM Omen Technology ZMODEM gives you
the tools to maintain up to date files on multiple machines. You can
use the ZMODEM n option to transfer only those files that have changed
since the last time they were transferred. With the p option, you can
unconditionally protect files that exist on the destination system.
To update only the files you already have while skipping the rest, use
the Yn options. You can update an entire directory subtree with the R

SEE ALSO: File Transfer Options, Chapter 20.

2.4.2 MobyTurbo Accelerator Standard ZMODEM escapes network control
characters. This causes a slight drop in throughput when sending
compressed files. When transferring compressed files over circuits
that pass all 256 8 bit codes, Moby Turbo(TM) may be used to optimize
speed. MobyTurbo provides the raw transfer speed of YMODEM-g and
other fragile protocols without sacrificing ZMODEM's safety or

MobyTurbo is activated with the m option. The m option may be used
with the sz or rz command.

EXAMPLE: sz -m *.zip

MobyTurbo may be used with ZMODEM AutoDownloads by adding the m option
to the DSZOPT environment variable.


SEE ALSO: m file transfer option

2.4.3 ZMODEM Compression ZMODEM-90 programs support ZMODEM
compression for fast transfers of compressible files with the Z file
transfer option. The amount of compression (and speed increase)
depends on the structure of data in the files.

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Protocol File Transfers 7

EXAMPLE: sz -Z pcmagc.dmp

SEE ALSO: Z file transfer option

2.5 Receiving files with ZMODEM

2.5.1 ZMODEM AutoDownload YAM's term function (t command) will
detect a ZMODEM transmission, and receive the file(s) automatically.
File transfer options for ZMODEM automatic downloads may be specified
with the DSZOPT environment variable.

EXAMPLE: C> set DSZOPT=m Requests MobyTurbo(TM) accelerator for

.H 3 "Manual ZMODEM Downloads" The rz command may be also given from a
command prompt.

SEE ALSO: rz command

2.6 Tuning ZMODEM Parameters

Chapter 24.2 describes a number of ZMODEM numeric parameters which may
be adjusted for extraordinary situations, or to fine tune the last 0.1
per cent of possible performance.

The ZMODEM subpacket length (zmodem L parameter) and the ZMODEM frame
length (zmodem l parameter) deserve special mention. People tend to
confuse these with the familiar 128 and 1024 byte block length used in
XMODEM transfers.

When a ZMODEM frame length of 0 is specified (the default), a single
frame will span the entire file if there are no errors. This is the
main source of ZMODEM's reputation for fast transfers.

Setting the ZMODEM frame length to a number between 64 and 16384
restricts the frame length to that value. At the end of each frame,
the sender stops sending and waits for an acknowledgement from the
receiver. When set, the ZMODEM frame length corresponds in function
to the 128 or 1024 byte block length of XMODEM based protocols.

Each ZMODEM frame consists of one or more subpackets of 32 to 1024
bytes. Since the subpackets within a frame are sent without pause, a
short subpacket length does not exact the terrible throughput penalty
associated with short XMODEM and Kermit blocks. In the absence of
transmission errors, a 256 byte subpacket length has about two per
cent more overhead than a 1024 byte subpacket length. However, the
longer subpacket length does increase error recovery time.

Professional-YAM dynamically adjusts the ZMODEM subpacket length on
the basis of transmission speed and observed error rate. If you know

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8 Protocol File Transfers

what the error rate on a particular call will be before starting a
ZMODEM file transfer, setting the zmodem L numeric parameter will
provide a small but noticeable improvement in performance, with 1024
best for clean lines and smaller numbers better for noisy lines.

When sending files over noisy phone lines not involving networks, the
speed of error recovery may be increased by decreasing the values of
the ZMODEM t and p numeric parameters.

Information about YMODEM and ZMODEM protocol internals is provided in
ymodem.doc and zmodem.doc, part of Omen Technology's ZMODEM
Developer's Collection.

2.6.1 Receiver Window Size Override Some ZMODEM senders control the
network window size to improve error recovery and/or overcome bad flow
control configuration. The optimum size of this depends on the
average error rate on the link, information that may not be available
to the sender. ZMODEM-90(TM) allows the receiver to specify the
window size, with the Wn option, overriding the sender's window size.

SEE ALSO: Wn option

2.6.2 Terminal Multiplexers Terminal multiplexers and telnet servers
provide a semi transparent serial link to host computers. The sz e
and m options may be used in conjunction with the xmtxesc and zmrxesc
string parameters to specify more control characters which cannot be
passed over the serial line.

SEE ALSO: zmtxesc, zmrxesc string parameters for details

2.6.3 7 Bit Environments ZMODEM-90 automatically detects 7 bit
environments and adjusts accordingly. If the environment is known to
be 7 bits, use the E option to provide 7 bit compatibility in minimum

EXAMPLE: sz -E file.doc

When transferring files with a large number of bytes with the 8th bit
set, the P ("pack") option may be used to optimize 7 bit encoding.


2.6.4 Manual ABORT If a ZMODEM transfer fails abruptly under
exceptional conditions the program on the remote machine may be
manually terminated by repeatedly typing Ctrl-X characters at it until
the program exits.

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2.7 XMODEM Family Protocols

All XMODEM family protocols require an absolutely transparent data
path from sender to receiver. Modems must not be configured for
software flow control.

2.7.1 TRUE YMODEM(TM) Developed in 1981, YMODEM is finding its way
into many communications programs. With Omen Technology's Enhanced
Data Recovery(TM), YMODEM gives excellent efficiency, integrity, and
good robustness in many applications.

True YMODEM transfers one or more files in a batch, without alteration
or added garbage characters. True YMODEM also preserves the file date
across multiple time zones. Professional-YAM and the Unix(TM) rb and
sb programs preserve the file modification date.[3]

2.7.2 YMODEM-1k The sb k option (1024 byte blocks) may be used to
enhance throughput, especially when using timesharing systems,
satellite links, or packet networks that can support the longer

EXAMPLE: sb -k *.c *.h sends all .c and .h files in the current
directory with 1024 byte blocks.[4]

YMODEM and YMODEM-1k transfers can be received with the rb or F3

YMODEM file transfers with Unix and VMS systems are discussed later in
this chapter.

Some programs claim to support YMODEM but actually use XMODEM with
1024 byte blocks. These programs do not meet the YMODEM Minimum
Requirements defined by the YMODEM protocol.

One can use Pro-YAM's XMODEM sx -k and rc commands with these
traditional programs.

2.7.3 YMODEM with OverThruster YMODEM and YMODEM-1k file downloading
from networks and timesharing systems is slowed by response times.
This slowing may be significant even when 1k blocks are used. With


3. Controlled by the d and z numeric parameters

4. YAM switches to 128 byte blocks at the end of a file when the
length warrants.

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10 Protocol File Transfers

some systems, one can speed up YMODEM downloads by using the o option
with the rb command to receive the file. Because OverThruster(TM)
defeats error recovery, a line hit will usually abort a download.
OverThruster(TM) may be used with X.PC or MNP error correcting link
level protocols.

EXAMPLE: rb -o

SEE ALSO: O numeric parameter

2.7.4 XMODEM-1k The XMODEM-1k protocol transfers one file per
command with 1024 byte blocks and a nominal 16 bit CRC. The file name
must be entered for both the sender and the receiver. Programs
lacking YAM's Cybernetic Data Recovery(TM) logic are less likely to
transfer data accurately under marginal conditions. XMODEM's use of
every possible 8 bit code causes problems in some applications.

The end of the file may be padded by up to 127 or 1023[5] garbage

To send a file with XMODEM-1k: sx -k file1

To receive a file with XMODEM-1k: rc file1

2.7.5 XMODEM-CRC (with fallback) The XMODEM-CRC protocol transfers
one file per command. The XMODEM-CRC protocol requires the receiving
program to initiate an XMODEM-CRC transfer.

The file name must be entered for both the sender and the receiver.
Even with CRC-16, programs lacking YAM's Cybernetic Data Recovery(TM)
are less likely to transfer data under marginal conditions. XMODEM-
CRC's use of every possible 8 bit code causes problems in some

The end of the file may be padded by up to 127 garbage characters.

To send a file with XMODEM (or XMODEM-CRC): sx file1

To receive a file with XMODEM-CRC: rc file1

2.7.6 Classic XMODEM The original MODEM protocol, developed by Ward
Christensen, is supported by a large and growing number of programs
operating on a variety of micros and minis. The base level XMODEM
protocol gives good results when used over low error rate direct


5. Some programs (including YAM) limit this padding to 127 bytes.

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telephone connections. XMODEM's short data blocks and use of every
possible 8 bit code preclude its application in many environments.

File transfers with this protocol add up to 127 garbage characters to
transferred files. The XMODEM protocol can transfer one file per
command. The file name must be entered at both the sender and the

To send a file with XMODEM: sx file1

To receive a file with Classic XMODEM: rx file1

2.7.7 Relaxed XMODEM Professional-YAM's XMODEM and YMODEM support
has been optimized for maximum reliability with a wide variety of
systems under a wide variety of conditions.

The default XMODEM and YMODEM timeout parameterss are "relaxed"
timings. They rarely need to be lengthened except under the most
sluggish of conditions. The zmodem t, T, and p numeric parameters
(q.v.) control timeouts for XMODEM, YMODEM, and ZMODEM. The default
values allow 10 seconds for a packet to appear and a 10 second pause
within a packet before starting error recovery.

EXAMPLE: zmodem pt200 pp150 :: Set more relaxed X/Y/ZMODEM timing

For best reliability, Omen Technology does not recommend tightening
these timings for XMODEM and YMODEM transfers on noisy lines.

2.7.8 XMODEM with OverThruster XMODEM file downloading from networks
and timesharing systems is slowed by short blocks and long response
times. With some systems, one can speed up downloads by using the ro
command to receive the file. Because OverThruster(TM) defeats error
recovery, a line hit will usually abort a download. With nearly error
free connections, one can save enough time from the increased
throughput to make up for the failed transfers. OverThruster(TM) may
be used with X.PC or MNP error correcting link level protocols.

EXAMPLE: ro file1

EXAMPLE: rb -o

SEE ALSO: O numeric parameter

2.7.9 YMODEM-g: Traditional Overdrive The proliferation of error
correcting modems has sparked a proliferation of YMODEM-g programs,
more and more of which actually meet minimal YMODEM protocol

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YMODEM-g transmits 0 or more files per batch with an ACK-less variant
of YMODEM-1k. The sender does not wait for individual data blocks to
be acknowledged, allowing high speed transfers with error correcting

YMODEM-g assumes an error free communications channel. A single
transmission error or character lost because of DOS or TSR interrupt
latency ruins the entire transfer, and YMODEM-g does not support Crash

YAM supports True YMODEM-g with the sb and rb -g commands.

EXAMPLE: sb *.old Sends files in the current directory with YMODEM or
YMODEM-g protocol. The receiver controls whether YMODEM or YMODEM-g
is used for the transfer.

EXAMPLE: rb -g Receives with YMODEM-g protocol.

2.7.10 XMODEM Mutants Misrepresented as YMODEM Despite continuing
education efforts, a few lazy software providers insist on identifying
their mutant XMODEM protocols as "ymodem". They choose to ignore the
definition of YMODEM that Ward Christensen wrote when he coined the
term YMODEM in his April 1985 message:

(a) a record 0 containing filename date time and size
(b) a 1K block size option
(c) CRC-16.

Use the XMODEM sx-k and rc commands to deal with these nonstandard

In case of questions, please refer to ymodem.doc, part of yzmodem.zoo
for for the official YMODEM protocol. (Available in Omen's ZMODEM
Developer's Collection.)

2.7.11 Qmodem-G/Streaming XMODEM The Qmodem program and certain
bulletin boards provide an ACKless XMODEM mutant protocol selected
with the Qmodem G protocol menu choice.

The sx and rx -g commands support this mutant XMODEM.

EXAMPLE: rx -g qmodem.fil

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2.8 Transferring Files with Unix Systems

Some Unix systems are accessed via a port multiplexer or other
network. Some of these networks interfere with data transmission.
These systems may require additional control characters to be escaped.
The sz command e option may be used to escape all control characters.

SEE ALSO: e option

Individual control characters can be escaped with the zmtxesc string

SEE ALSO: zmtxesc string parameter

2.8.1 Uploading Files to Unix Systems Files may be uploaded to Unix
systems conveniently and quickly with ZMODEM. Unix flavors of
Professional-YAM support the full ZMODEM-90(TM) feature set including
Intelligent Crash Recovery(TM) and selective transfers with the rz
command, a hard link to the /usr/bin/yam program.

If the Unix system is operating with 7 bits, the sender's zmodem d
parameter may have to be increased to allow the rz program time to
change Unix to 8 bits for the transfer.

SEE ALSO: zmodem d numeric parameter

Professional-YAM is the fastest Unix ZMODEM upload program. Pro-YAM
uses a minimum of CPU resources for uploads. Pro-YAM provides the
best ZMODEM technology and feature set available., but it may not be
available on a particular system. The rz program, part of the rzsz
package, may be used to support a subset of Pro-YAM's ZMODEM features.

If rz is not installed on the Unix system, unpack the rzsz.zoo file on
your MSDOS system with: booz x rzsz.zoo given from the DOS prompt.[6]
Next, the command source zupl.t calls the zupl.t script to upload the
bootstrap file minirb.c, compile it, and use it to upload the
remainder of the source files. After the rest of the files have been
uploaded, compile rz.c and sz.c using the directions given in the
README file and in the C source files.

The rz and sz manual pages may be formatted with a make doc command.

The undos program may be used to remove carriage returns files


6. On Unix systems with Professional-YAM installed, the rzsz source
files and man pages are installed in the /usr/src/command/rzsz

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14 Protocol File Transfers

uploaded to Unix machines.

2.8.2 Downloading Files from Unix Systems To download files from
Unix(TM) systems, use the Unix sz command to send the desired files to
YAM. To Unix keyboard: sz file ... Professional-YAM's ZMODEM
AutoDownload(TM) takes care of the rest for you, saving unnecessary

If one or more of the files already exists on the destination disk,
use sz -y file ... instead, to replace the old copies on your

Another useful option sends only the files that exist on both
computers (Y), and furthermore sends only those that are newer (n):
sz -Yn file ...

When files are long and transmission slow, you can save time by
compressing them first. The zoo program, available for DOS and Unix,
may be used to compress file(s) before transmission.

Omen Technology products support ZMODEM compression with the Z option.
All Omen Technology products support compression by Run Length
Encoding (RLE). Unix flavors of Professional-YAM also support LZW

Unix source files normally do not contain carriage returns used by
CP/M and DOS. Some CP/M or DOS programs, such as C compilers, do not
require carriage returns in the source files. Others, such as the
Microsoft Macro Assembler, become quite confused by such files,
although such files fully meet the requirements of the ASCII standard.

Carriage Returns may be added before downloading with the todos or
tocpm programs. Carriage returns may be added during the transfer
with the sz a option. Carriage Returns may be added after the
transfer by some program editors, including uEMACS. (Other editors,
such as DOS edlin may crash trying to edit such files.) Short files
(less than 64kb) may be converted using YAM's read and create commands
to pass the data through YAM's capture buffer.

Text files may also be downloaded using the capture buffer if sz has
not been installed on the Unix machine.

If a file or set of files are to be transported between two Unix
systems, it may be helpful to place them in a tar or cpio archive (and
possibly compress the archive) before transmission. This procedure
will preserve the Unix file modes and modification times, and bypass
pathname restrictions imposed by DOS.

As with rz, Unix Professional-YAM is linked to sz to support the full
ZMODEM-90(TM) feature set. Otherwise the separate Unix sz program may
be obtained as described in the previous subchapter.

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2.9 VAX/VMS File Transfers

Most of the comments made above about Unix file transfers apply to VMS
as well. Many VAX/VMS systems attach terminals with terminal
multiplexers just as nasty as those used with Unix systems. They
require fixes similar to those described above for Unix systems..

Automatic uploads to VMS may require setting the zmodem d (delay)
numeric parameter to give time for the VMS rz program to properly

SEE ALSO: zmodem d numeric parameter

EXAMPLE: zmodem pd15

2.9.1 Version 4 rz/sz Omen provides VMS flavors of version 4 rz and
sz precompiled in rzsz.tlb, a VMS "text library". Version 4 rz
supports most ZMODEM-90 features including Crash Recovery,
compression, and MobyTurbo. Binary uploads write files with a default
VMS 512 byte fixed length record format.

EXAMPLE: sz biglib.tlb

Sending to VMS with the i option selects the VMS Stream_LF record
format. Stream_LF preserves the exact file length and data contents
when read by C programs.

EXAMPLE: sz -i vmsemacs.exe

Sending to VMS with the I option causes the VMS receiver to use
variable length binary records. VMS Kermit-32 and some other programs
understand this record format.

Text files uploaded with the a option are written in variable length
records with CR carriage control.

EXAMPLE: sz -a emacs*.c

Version 4 VMS sz supports standard VMS wild card and directory
recursion syntax.

EXAMPLE: $ sz -qa [*...]*.prn sends all accessible .prn files on the
system in ASCII mode. The VMS sz q option suppresses the initial tally
of the number of files and their lengths. This tally can take some
time when a large number of files and directories are invloved. The f
option may be added to send directory names as well.

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If you use Kermit to upload the rzsz.tlb file to VMS, command the
receiving Kermit program to SET FILE TYPE FIXED. (Some VMS Kermit
programs may require SET FILE TYPE BLOCK.) Otherwise Kermit will
garble the data.

2.10 GEnie File Transfers

The General Electric Consumer Information Service service (GEnie) uses
ZMODEM-90(TM) for efficient downloads. GEnie's ZMODEM server selects
ZMODEM RLE Compression or MobyTurbo(TM) for optimum download speed on
each file.

GEnie uses a large network to provide callers with local access
numbers. This requires technical tradeoffs to control data flow in
the network. If you are using an MNP modem, download speeds can be
improved by increasing GEnie's ZMODEM window size.


The sx file.exe command is used for XMODEM-CRC uploads to GEnie. When
uploading with XMODEM-CRC, Wait for GEnie's "READY FOR INPUT, start
your XMODEM upload." message, and then wait for the XMODEM-CRC C to
appear before issuing the sx command. Issuing the sx command before
the C appears may corrupt the uploaded file.

A number of GEnie access scripts are provided in scripts.zoo with
filenames starting with ge. The main GEnie login script is provided
in phones2.t witin scripts.zoo.

2.11 BIX File Transfers

BIX (Byte Information Exchange) supports ZMODEM-90 and Kermit file

The Tymnet phone number in the bix telephone directory entry should be
changed for your calling area. Other scripts are provided to handle
BIX mail and conferences.

When setting up a new BIX account, give the command call bix,new to
force a login to the BIX new account program.

Be sure to select ZMODEM downloads and uploads with the BIX "OPTIONS"
menu choice. Set the DSZOPT environment variable m or mr to enable
MobyTurbo and ZMODEM Crash Recovery.

When uploading over Tymnet or other networks, it may be necessary to
set the zmodem w numeric parameter to a value between 2048 and 8192
for best upload performance. The optimum value depends on load and
the particular node you dial in to.

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EXAMPLE: z pw6144

BIX's transfer time predictions are about 40 per cent too pessimistic
for ZMODEM transfers.

A number of BIX scripts are included in SCRIPTS.ZOO.

====____\ /.. ..\ /____====
// ---\__O__/--- \\
\_\ /_/

Enterprise... Surrender or we'll
send back your *&^$% tribbles !!!
-A Usenet Signature

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18 Flow Control


All of us must sometimes tell people to "slow down" lest they overload
us with information faster than we can write it down. "Wait!" is a
Flow Control Signal for the English language. When the receiving
Pro-YAM complains about Garbled Data Subpacket or Line Status Register
01 you should suspect a flow control problem.

When buffered modems, timesharing systems, networks, or computers of
differing speeds are involved, a machine readable "Wait!" signal is

Flow control is sometimes necessary to display long messages without
skipping over the good parts. If you see pieces of text missing from
messages but don't see the usual funny characters caused by line
noise, you have a flow control problem.

File transfers that use long blocks or streaming protocols may not
work well unless slower parts of the system regulate the speed of
transmission to prevent loss of data. With ZMODEM, SuperKermit, and
other streaming protocols, inexplicable retransmissions of data
blocks, often at regular intervals, indicate flow control failure.

If you wish to keep things simple, the sending computer should not
operate at a higher interface speed than the slowest link in the
network. Otherwise precautions must be taken to prevent data loss
with interactive operations and unnecessary retransmissions with
streaming file transfer protocols.

YAM, ZCOMM, and DSZ default to software flow control with XON and XOFF
characters.[1] When used with modems that require hardware flow
control, the handshake command (q.v.) should be used to specify which
hardware lines are to be used for flow control.

Non transparent software flow control is incompatible with Emacs
editors, XMODEM and YMODEM transfers. XMODEM and YMODEM require
complete transparency to all 256 8 bit codes. An XMODEM transfer that
always fails at the same block results from non transparent flow
control. When XMODEM-1k and YMODEM-1k are used, the network must
assert flow control, or handle bursts of 1040 characters without data
loss. When X.25 or hardware CTS is unavailable, flow control that
does not "eat" any characters may be used with XMODEM and YMODEM.
When buffers fill up, an XOFF should be emitted. An XON should be


1. The PCDOS flavor enables "handshake both" when selecting a port
with an active Clear To Send (CTS) signal that was previously
initialized to a speed greater than 2400 bps

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sent when the buffer has emptied. Otherwise, the network should
neither generate nor eat XON or XOFF characters.

On Telenet, this is obtained by setting CCIT X3 5:1 and 12:1 in the
PADs (Packet Assembler Disassembler) at both ends of the network.
Packets should be forwarded when the packet is a full 128 bytes, or
after a moderate delay (3:0,4:10). Set parameter 5 to 1 at both ends
AFTER one is connected to the remote modem. (Sorry, these commands
must be given each time you connect to a modem in the far city!)
set 5:1
rst? 5:1
ZMODEM and Kermit protect all 4 XOFF and XON characters, commonly used
network control characters and trigger strings. ZMODEM and Kermit are
compatible with many networks that do not support XMODEM family
protocols, including some that claim network compatibility. For PADs
that do not accept "rst?", use:
set 4:2,5:1,12:1
For best Telenet download throughput, parameter 64 (advance ACK)
should be set to 7. The parameter 0 is a dummy argument that
distinguishes Telenet parameters from CCIT parameters.
set 0:0,64:7
Sometimes Telenet flow control stops data transmission when the
network buffers are not yet full. If you often see "STOPPED" flashing
in the status line (DOS versions), or if you see the modem send data
light pause in a ZMODEM or SuperKermit file send, poor flow control
may be the culprit. Such slowdowns are typical when a network is
overloaded. If this condition persists, the network should take steps
to reduce the congestion. Turning OFF network flow control and
activating ZMODEM's or SuperKermit's protocol flow control may
increase throughput under these conditions.

Instead of or in addition to XON/XOFF flow control, the sending
program's ZMODEM w numeric parameter can restrict the window size to a
value that does not overload the network. A zmodem pw2048 command
restricts the window size (maximum number of bytes in transit) to
2048. This causes the sz command to trigger the receiver's
acknowledgement every 512 bytes (one fourth the value of the ZMODEM w
numeric parameter). The sender monitors these responses and suspends
transmission when necessary to restrict the window to the specified
size. Until a network dependent lower limit is reached, lower window
sizes improve the speed of error recovery at the expense of slight
increases in protocol overhead. When the window size becomes less
than the number of characters sent within the network's transit time,
throughput falls off rapidly. Frequent protocol acknowledgements slow
down high speed pseudo full duplex modems (US Robotics HST, Telebit

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TrailBlazer) and should be avoided.

ZMODEM-90(TM) allows the receiver to specify the window size with the
-Wn option where n is the desired window size. requests an 8192 byte
window size.

Some modems and networks can be configured to flush (discard the
contents of) their buffers when a break signal is received. If this
is possible, error recovery with ZMODEM transfers may be speeded up by
setting the ZMODEM b parameter to 1, which sends a break whenever the
ZMODEM sending program gets a retransmission request.
Network and Flow Control (FC) Compatibility

| Network | Interactive | XMODEM | WXMODEM | S-KERMIT | ZMODEM |
|No Network | YES | YES | YES | YES | YES |
|8 bit, no FC | NO | YES | YES | YES(1) | YES(1) |
|Transparent FC | YES | YES | YES | YES | YES |
|Non Transparent | YES | NO | NO | YES | YES |
|7 bit | YES | NO | NO | YES | YES(2) |

(1) Window size must be restricted to avoid buffer overrun if the
network cannot transfer data at full speed.
(2) Requires ZMODEM-90(TM) 7-bit support

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Commands and arguments must be entered in lower case except where

estimate length speed Use the specified length and specified effective
speed for the next receive file to be created. A length of 0
bypasses the length substitution. Once a speed (in effective bits
per second) is given, it is used for all locally displayed
transmission time calculations until the next speed or port command.

EXAMPLE: "speed 19200; estimate 0 2400" Use an effective
transmission speed of 2400 for transmission time estimates instead
of the 19200 bps interface speed.

HAndshake {off|on|cts|dsr|dcd|both|slow} Some modems and printers
cannot accept continuous full speed data. These devices send
control characters (XOFF and XON) for flow control, or generate a
hardware flow control signal on the CTS, DSR, or DCD pin. The
Handshake command controls the modem port hardware handshake
(default off).

If hardware handshaking is selected, an ON to OFF transition on the
specified line pauses transmission, and an XON character will not
override the hardware restraint.

After a timeout set by the S numeric parameter (default 60 seconds),
or if characters are in the keyboard input buffer, a warning message
is displayed, the restraint is released, and characters are sent.

As a special case, handshake on obeys output flow control with the
CTS input signal, asserts input flow control with the RTS output
signal, and disables the transmission of XOFF characters when the
modem input buffer becomes nearly full. In addition, handshake slow
drops the RTS output signal while writing to disk when receiving

The command handshake both allows either CTS or XOFF to pause
output, in addition to asserting input flow control with the RTS

The handshake dcd command enables d term option (q.v.).
Subsequently, selecting a different type of handshaking will disable
d term option.

The handshake command releases flow control (allows data to flow if
it had been stopped by handshaking).

Changing the communcations port with the port or portx command
disables hardware handshaking.

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SEE ALSO: S numeric parameter

EXAMPLE: handshake cts Turns on CTS handshaking.

port n Change the modem port to COMn. On DOS, the legal values for n
are 1...18.

Selecting a new port normally selects software handshaking
("handshake sw"). The PCDOS flavor enables both hardware and
software handshaking ("handshake both") iff the port speed exceeds
2400 bps and the Clear To Send (CTS) signal is active at the time
the port command is given.

Standard Ports (PCDOS):
COM1 3F8 IRQ4 (Standard IBM)
COM2 2F8 IRQ3 (Standard IBM)

COM3 3E8 IRQ4 (Alternate)
COM4 2E8 IRQ3 (Alternate)
COM5 2B8 IRQ3 (Columbia)
COM6 2B8 IRQ2 (Alternate for IBM)

COM7 2E8 IRQ5 (Alternate "COM3")
COM8 3E8 IRQ5 (Alternate "COM4")

COM9 Uses the port address and interrupt vector
previously set by the portx command.
COM11-COM18 IBM PS/2 COM1-COM8 ports

COM1 and COM2 are the standard serial ports defined by the IBM
Technical Reference Manual.

COM3 and COM4 are supported by many serial cards and modem boards.
COM3 and COM1 share the same dedicated hardware interrupt line, and
these ports may not be used at the same time. Likewise, COM4 and
COM2 may not be used at the same time.

Columbia computers support COM5.

COM6 to COM8 are alternate configurations that may be accessed by
cross jumpering between printer port decoders and serial port
enables on some multifunction boards.

COM7 and COM8 support alternative definitions for "COM3" and "COM4"

COM11 to COM18 correspond to "COM1" to "COM8" on IBM PS/2 computers.
Only one of COM12-COM18 may be used at a time unless using the

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special OS/2 comm driver for that board.

Since YAM uses the interrupt line on the selected port, no other
program or device driver may use the same port address and/or
interrupt vector concurrently. Certain disk controllers and mice
interfaces use IRQ2 and IRQ5. Do not use IRQ2 on a PC-AT (the extra
8259 is not reset). IRQ5 is sometimes used by network cards and
printer ports. Do not select COM3 to COM18 unless you are familiar
with the I/O addresses and interrupt vectors used in your machine.
Ports sharing the same interrupt vector (IRQ number) cannot be used

The port command sets the d term option (which suppress the No
Carrier Detect message).

EXAMPLE: port 2

DOS YAM begins with COM1 unless overridden by the DPORT environment


On Unix, the argument of the port command is a character special
file in the /dev directory. Unix and Xenix flavors have no default
port. If the DPORT environment variable is set, that port will be
selected when Pro-YAM initializes. Otherwise, a port is selected by
the startup and/or dialing script. Typical values are tty01
(386/ix) and tty2A (Xenix).


SEE ALSO: handshake command, dport string parameter

portx hbase,irq * To support specialized multiport serial interfaces,
the portx command selects a communications port with a specified
hexadecimal base address hbase and Interrupt Request Line irq (3 <=
irq <= 7).[1] The portx does not check its argument for validity.
The consequences of an invalid selection are quite undefined. The
specified base address and IRQ number are assigned to COM9, where
they may be used by the port command and the x numeric parameter.
The status line and s command will indicate COM9. This command not
available on X.PC, Unix, Xenix, or OS/2.


1. IRQ2 can be used on some machines.

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EXAMPLE: portx 3f8,4 Selects a comm port with a base address of 3f8,
using IRQ4.

rb [-options] Receives with options 1 or more files using YMODEM
protocol. The rb command also receives files sent with SEAlink
protocol. Chapter 20 describes the available options. YMODEM
transmits the pathname and length of each file. If a file is
received in error (retries exhausted, etc.), the batch transfer will
terminate. If Restricted, a file received in error will be unlinked

EXAMPLE: rb -y Receive file(s) with YMODEM replacing old files, if

EXAMPLE: rb -g Receive file(s) with YMODEM-g.

Many programs claiming to support YMODEM actually use XMODEM with
1024 byte blocks; use YAM's sx -k, rx and rx -g XMODEM commands with
these mutants.

SEE ALSO: YMODEM protocol, Chapter 13.

rb [-options] [dir] [file ...] Receives with options 1 or more files
using YMODEM protocol. An optional disk and/or directory dir may be
specified. The optional supplied pathnames file ... are used in
place of pathnames normally provided by the sending program. If the
sending program attempts to send more files than the number of names
supplied to the rb command, the transfer is aborted.

rc [-options] file Receives with options a single file using the Ward
Christensen XMODEM protocol, 128 or 1024 byte blocks, and CRC-16
instead of an 8 bit checksum. YAM signals the sending program that
CRC-16 is to be used. After four errors while attempting to receive
the first sector, YAM will cancel the CRC-16 option and reverts to
checksum operation.

The probability of an undetected transmission error is much less if
CRC-16 is used in place of the default 8 bit arithmetic checksum.
Omen Technology Incorporated Recommends use of the 16 bit CRC to
maintain data integrity at professional levels. Chapter 20
describes the available options to the rc command. If Restricted, a
file received in error will be deleted.


SEE ALSO: XMODEM-CRC protocol, Chapter 13.

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ro [-options] file Receives with options a single file using non-
standard XMODEM-CRC protocol logic. OverThruster(TM) speeds file
downloads at the expense of error recovery. OverThruster operation
is controlled by the O numeric parameter. As fans of Buckaroo
Bonzai know, the OverThruster is not universally applicable. A
transmission error will almost always terminate an OverThruster file

If Restricted, a file received in error will be unlinked (erased).


SEE ALSO: O numeric parameter

rx [-options] file Receives with options a single file using the Ward
Christensen XMODEM protocol. CRC-16 is not the default because most
commercial comms programs only support the 8 bit checksum. Chapter
20 describes the available options. If Restricted, a file received
in error will be unlinked (erased).


The rc command should be used whenever possible instead of rx.

EXAMPLE: rx -g foo.txt Receive a single file with an ACKless XMODEM
protocol mutant incorrectly called "ymodem-g" by PCBoard and Qmodem

SEE ALSO: XMODEM protocol, Chapter 13.

rz [-options] Receives with options 1 or more files using ZMODEM
protocol. Chapter 20 describes the available options. Each file's
pathname is obtained from the sending program. The +, a, b, n, N,
r, and y options are accepted from the sending program, subject to
Restriced privileges. If the +, b, n, N, r, or y option is
specified to the receiver, it overrides any contrary options
specified to the sender. Only one of the a, b, or r options may be
specified. Only one of the +, n, N, or y options may be specified.
If a file is received in error (retries exhausted, etc.), the batch
transfer will terminate. If Restricted, a file received in error
will be unlinked (erased).

EXAMPLE: rz -y

SEE ALSO: Z term option

SEE ALSO: ZMODEM protocol, Chapter 13.

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rz [-options] [dir] [file ...] Receives with options 1 or more files
using ZMODEM protocol. An optional disk and/or directory dir may be
specified. The optional supplied pathnames file ... are used in
place of pathnames normally provided by the sending program. If the
sending program attempts to send more files than the number of names
supplied to the rz command, the transfer is aborted. To allow use
of the rz command, Z term option (ZMODEM AutoDownload) should be
turned off with a dis -Z command.

sb [-options] [PREFIX=p | ONAME=x] pathspec Send the files specified
in pathspec using True YMODEMTm Protocol. The pathname, length, and
modification time of each file are transmitted. Files which cannot
be opened are skipped. An empty pathspec sends all files in the
current directory. A directory name expands to all regular files in
that directory.

If an error aborts a file transmission (retries exhausted, etc.),
batch transfers terminate. The sb command will send files with
SEAlink protocol if the receiving program requests SEAlink.

EXAMPLE: sb -k *.com Sends *.com using 1024 byte packets.

The receiver must be commanded to receive the files with an rb
command. Unix and OS/2 users: sb command cannot be used to send
source files that grow after the beginning of transmission.

SEE ALSO: YMODEM protocol, Chapter 13, SEAlink protocol, Chapter 13.

sx [-options] file Send a single file using the Ward Christensen
XMODEM or XMODEM-CRC protocol. The receiving program may request
use of a 16 bit CRC, which is more accurate than the default
checksum. DOS/Unix files sent this way will have Control-Z (CPMEOF)
garbage characters appended to make the file length a multiple of


EXAMPLE: sx -k Sends using 1024 byte blocks

The receiver must be commanded to receive the file with an rx
filename or rc filename command.

SEE ALSO: XMODEM, XMODEM-1k, XMODEM-CRC protocols, Chapter 13.

sz [-options] [PREFIX=p | ONAME=x] pathspec Send the files specified
in pathspec using ZMODEM Protocol.[2] If the remote supports ZMODEM

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AutoDownload, or accepts rz followed by carriage return as a command
to receive files with ZMODEM protocol, only the sz command need be
given. Otherwise, the receiver must be commanded to receive the
files with an rz command or menu choice.

The +, a, b, n, N, r, y, and Z options are sent to the receiving
program. Only one of the a, b, or r options may be specified. Only
one of the +, n, N, or y options may be specified.

Each skipped file is counted as an error as indicated by the e test
condition and e numeric parameter. If the q option is used, files
skipped as a result of selective file transfers are not counted as

The pathname, length, and modification time of each file are
transmitted. Files which cannot be opened are skipped. An empty
pathspec sends all files in the current directory. A directory name
expands to all regular files in that directory.

If ONAME=x is given after the options (if any) and before the file
name(s), x will be used exactly as given as the COMPLETE destination
pathname instead of each file's actual pathname. It is the sender's
responsibility to use lower case for x unless the filename is really
supposed to be all caps.

EXAMPLE: sz -y ONAME=B:/spiked/secret /soviet/sdi/newlaser.doc
Results in the destination file secret on drive B: in the /spiked
directory. (Destination directories must exist and be writable).

If instead PREFIX=p is given after the options (if any) and before
the file name(s), p will be added to the destination pathname(s) as
a prefix. It is the sender's responsibility to use lower case for p
unless the prefix is really supposed to be all caps.

EXAMPLE: sz -y PREFIX=C:/foobaz/ /biff/bam/aardvark.wak
Results in the destination file "C:/foobaz/aardvark.wak"

EXAMPLE: sz *.com Sends all files with a .com extension.

EXAMPLE: sz -r ??log Crash Recovery sends only the new data if the
receiver has incomplete versions of these files.


2. The receiver may use the sz command to send files by uploading an
sz command with the zcommand command.

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EXAMPLE: sz -fn src/*.c src/*.h maildir
Sends only newer .c and .h files in the src subdirectory, and all
new files in the maildir subdirectory.

EXAMPLE: zcommand "sz -fn /bin /wp"
commands a remote YAM system in Host Operation (unrestricted) to
send all new files in the /bin and /wp directories.

EXAMPLE: sz -Yn *.c Sends only newer versions of files that already
exist at the destination.

EXAMPLE: sz -Rf usera Sends all files in the usera directory and all
subdirectories thereof. Directories are not sorted when the R
option is used on 16 bit systems.

SEE ALSO: ZMODEM protocol, Chapter 13, Options, Chapter 20.

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5. Protocol File Transfer OPTIONS

Options modify the way the protocol file transfer commands send and
receive files. They are reset before each command line.

The a, b, r and rr options are mutually exclusive. With ZMODEM, a b
option given to the sender or receiver will override any a option.

The +, c, r, rr, N, n, p, and y options are mutually exclusive. The Y
option may be followed by the c, +, r, n, or N option. Specifying
these options to the receiver overrides the ZMODEM sender's
specification of these options.

The DOS append command interferes with some of these options.

+ When receiving to a file already on disk, append the new data to
the file. If the specified file does not exist, it is created.
This option is not allowed if YAM is Restricted.

EXAMPLE: rc -+ evrybody.dat

When sending files with ZMODEM, the + option commands the receiver
to append to a file already on the receiver's disk.

EXAMPLE: sz -+ ONAME=master.log *.log sends all .log files in the
current directory to be appended to master.log on the receiver's

NOTE: Append (+) is not the same as crash recovery (-r). Append is
used to concatenate (add) new data to an existing file. The
resulting file contains both old and new data.
NOTE: If an append (+) file transfer is interrupted and restarted,
data may be duplicated.

SEE ALSO: r option

7 Strip data to 7 bits for file transfers with the Kermit protocol.
Program executables and other 8 bit binary files cannot be sent
this way. In the absence of the 7 option YAM transfers all 8 bits
of each byte. If the communications line is set to 8 bits no
parity, the 8th bit is transmitted, otherwise YAM requests 8th bit
quoting. NOTE: The 7 option is distinct from the 7e and 7o term

a (ASCII) The a option applies to files received with XMODEM, YMODEM,
or ZMODEM protocol. It converts newlines not preceded by CR to
CR/LF pairs. NULL, RUBOUT, and all characters in each packet
beginning with Ctrl-Z are excluded. The a option is useful when
receiving text files without carriage returns directly from Unix

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When sending with ZMODEM, the a option instructs the receiver to
convert text files to the conventions used in its operating
environment. When sending to VAX/VMS rz this selects CR carriage
control variable length record format.

The a option does not apply to the Kermit, sx, or sb commands.
Files transferred with the a option cannot be processed with the
ZMODEM r (recover/resume) option.

EXAMPLE: rc -a program.c receives program.c and converts end of
lines to CR/LF.

b (Binary) With ZMODEM, inhibits the receiver from translating the
file contents. If either the ZMODEM sender or receiver specifies b
option, any contrary requests will be ignored.

EXAMPLE: sz -b program.exe

c With ZMODEM, change the file name to prevent collision if the
destination file exists. The receiving program must support the
ZMODEM c option or file disposition will be undefined. The form of
the invented (changed) filename is implementation dependent.

Use CRC-16 with the rx, rt, and r7 commands.

e Normally, ZMODEM senders escape XON, XOFF, Ctrl-P, [email protected], and
Ctrl-X, and ZMODEM receivers ignore XON and XOFF. The e option
escape all control characters when sending files with the ZMODEM
protocol. In 7-bit environments, the e option also escapes RUBOUT
(7F).[1] This option is useful when operating with brain damaged
data PBX systems and other types of "front ends".

SEE ALSO: zmtxesc, zmrxesc string parameters

E With ZMODEM-90, force 8th bit encoding even if the transmission
medium appears to support 8 bits.[2]

f Send the full pathname as specified (exclusive of disk identifier)
when using a batch send command. Normally only the file name


1. In 7-bit environments, ZMODEM always escapes FF.

2. Not featured in DSZ.COM.

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Protocol File Transfer OPTIONS 31

portion (without any directory prefix) is transmitted. The f
option applies to batch file transmission with the kermit sb, sb,
send, and sz commands.

EXAMPLE: cd /src; sz -f robot/r2d2.h sends the file with the
pathname robot/r2d2.h.

EXAMPLE: sz -f /src/robot/vox/3tpi0.*

SEE ALSO: PREFIX=p flag for the sb and sz commands.

F Insert a pause after each transmitted data subpacket transmitted
with ZMODEM. This is useful in certain situations when
conventional flow control methods are unavailable, ineffective, or
unreasonably slow (i.e., "broken"). The length of pause is set by
the zmodem F numeric parameter.

EXAMPLE: sz -F honker.dat

SEE ALSO: zmodem F numeric parameter

g Given to the receiving program, the g option to the rb command
allows the sender and receiver to dispense with acknowledging each
transmitted packet when using YMODEM batch transfers. YMODEM-g
increases throughput when the transmitting medium itself (direct
connection, X.PC session, or error correcting modems) provides
error free transmission. The transmitting medium can use XOFF and
XON to enforce flow control.

If the transmitting medium does not enforce flow control,[3] the
user must insure the receiver is not overrun. YAM on a PC or XT
accepts data at 9600 bps without flow control when the file is
being written to a hard disk or ramdisk.[4]

If an error is detected when the g option is used, the transfer is

EXAMPLE: rb -g


3. X.PC automatically enforces end to end flow control.

4. Provided no memory resident programs or special drivers hog CPU

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The g option may also be used with the rx command to receive files
from Qmodem's G protocol.

i With YMODEM or ZMODEM, instructs the receiver to write file(s) in
stream oriented Image format. When sending to the VAX/VMS version
of rz, the i option selects Stream_LF record format. Stream_LF
preserves the exact contents of binary files read by VMS C
programs. Stream_LF is useful for file servers and archives that
service PCs, as well as C programs on VMS itself. (Without the i
option, the VMS rz default is 512 byte fixed length record format.)

I With YMODEM or ZMODEM, instructs the receiver to write file(s) in
variable length binary record Image format. When sending to the
VAX/VMS version of rz, the i option selects Variable length
(mrs=510) binary record format. Certain programs such as Kermit32
understand this binary record format better than Stream_LF.

k Use 1024 byte (1K) packets with the sb and sx commands. The
default packet length is 128. This increases throughput when the
speed is high relative to the response times of the communications
channel and the computers. The k option is useful with 9600 or
19200 bps transfers with directly connected timesharing systems.
The k option may not work properly uploading to some systems,
particularly heavily loaded or poorly implemented timesharing
systems at high speeds. The k option is valid only when sending to
YAM, Unix rb, or other compatible programs. If the file length is
not a multiple of 1024, the remainder of the file will be sent with
128 byte blocks. This option does not affect Kermit transfers.

EXAMPLE: sb -k *.c *.h

With the sz command, the k option forces an initial 1024 byte
subpacket length.

EXAMPLE: sz -k *.c *.h

l Force pathnames that are all uppercase to lower case. This option
is reset by the call command. This option is ignored on DOS and
OS/2 flavors of Pro-YAM.

m (ZMODEM-90) Activate MobyTurbo(TM) for maximum throughput on
compressed files sent over completely transparent connections.
MobyTurbo can be used over links that support YMODEM-g. Moby Turbo
can not be used with most forms of software flow control or over
networks that reserve control characters.

M Locks out Moby Turbo even if the other program has given the m
option. This option is useful if the transmission path does not
support complete transparency.

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n (ZMODEM) Each file is transferred if the corresponding destination
file does not exist, or if the source file is newer. The n option
can be given with either the sz or rz commands. This option is not
allowed if the receiver is Restricted.

EXAMPLE: sz -n *.* attempts to send all files in the current
directory. Only those files that do not exist in the destination
directory, and those for which the source is newer will be sent.

N (ZMODEM) Transfer the file if the corresponding destination file
does not exist, or if the source file is newer or longer. The N
option be used with the sz and rz commands. This option is not
allowed if the receiver is Restricted.

EXAMPLE: sz -N *.*

p (ZMODEM) Protect destination file; bypass this file if it already
exists on the destination system.

P (ZMODEM-90) When transferring files over 7 bit paths, pack 4 8-bit
bytes into 5 7-bit bytes for transmission instead of quoting the
8th bit.[5] This increases transmission speed on compressed files.

q (Quiet) suppresses block by block status line update during Kermit
and X/YMODEM file transfers. Also prevents skipped files from
incrementing the e numeric parameter and e test condition.

r (ZMODEM) Resume/Recover an interrupted file transfer with the
ZMODEM protocol. May be given with either the sz or rz commands.

The r option may be used to resume the transmission of a long file
after a disconnect or power loss, without having to start over at
the beginning of the file. The r option may also be used when the
source file grows from time to time and only the incremental
portion needs to be sent. The r option assumes that the contents
of the destination file are identical to the corresponding
beginning portion of the source file. The r option should not be
applied to a file that has been modified by the a option. This
option is not allowed if the receiver is Restricted.

EXAMPLE: sz -r hugefile.lst


5. Not supported in DSZ.COM.

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SEE ALSO: zmodem c numeric parameter

For convenience, the r option can be specified on all files if
desired, even those that have not been interrupted during a
transfer. However, if you do make the r option the default with
DSZOPT you could inadvertently overwrite valuable data with
unrelated data from a random file with the same file name.

The "ZMODEM Crash Recovery at NNNN" message may not appear when
performing Crash Recovery on very short files.

rr As above, but the files are compared by taking a 32 bit CRC on the
contents before deciding on whether to start a fresh transfer.

EXAMPLE: sz -rr maybenewer.lst

With the -rr option, all of the files are compared or transmitted
by default. The number of bytes used in the comparison may be
restricted by setting the zmodem R numeric parameter to a number
between 2048 and 32000 (1 billion on 32 bit flavors).

EXAMPLE: zmodem pR20000

s SlugBait modifies the logic of ZMODEM sending to detect and report
attempts at evading accountability for receiving files. Such
attempts are flagged with a Q status in the log of sent files.
SlugBait adds a slight delay to file transmission, and a transfer
that is cut off at the very end of file may very infrequently be
reported with Questionable instead of ERROR status.

S When sending file(s) with ZMODEM, interrogate the receiving program
for its serial number. S option terminates when a serial number is
received or when the call command is given. Receiving file(s) with
YMODEM or ZMODEM from programs providing a serial number also
provides the other program's serial number. The serial number
received is listed by the performance log.

t Enter the term function after file transfer(s) complete. The t
option should not be used in commands given from within the term
function, either directly or with soft key definitions.

u Unlink (remove, delete) the file after it has been sent with the sz

v View the data being transmitted or received. Only correct data is
displayed. Viewing standard ASCII files does not interfere with
correct transmission at high speeds, although throughput may be

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The output may be redirected to a capture file or DOS device with
the > or >> command. Unless output is redirected, this option must
not be used when YAM is in Host Operation.

When invoking Unix Pro-YAM as xyam, rz, sz, rb, sb, rx, or sx,
creates a logging file with information useful for debugging
purposes. More v's create more detailed debugging information.

SEE ALSO: v numeric parameter, LOGFILE environment variable

wN Use a window size of N bytes with the sz command, overriding the
zmodem w numeric parameter. If N is missing, use a ZMODEM window
size of 4096 bytes.

SEE ALSO: Flow Control Chapter 14, zmodem w numeric parameter

WN Request the sending program to use a window size of N bytes,
overriding the sender's window size setting, 4096 bytes if N is

y Yes it is OK to replace a file already on disk when receiving a
file. If absent, the operator is given a choice of appending to
the current file (a), erasing it (y) or aborting (n). This option
is not allowed if YAM is Restricted. When sending with ZMODEM,
commands the receiver to replace a file on its disk.

Y (ZMODEM) Transfer only those files for which a file with the same
pathname exists at the destination, overwriting the destination
files. The Y option may be followed by other ZMODEM options to
further qualify the selection of files to transfer. This option is
not allowed if YAM is Restricted.

EXAMPLE: sz -Yn *.* If the source directory contains files A, B,
and C, each dated today, and the destination directory contains B
and C, with B a week old and C dated today, only B will be sent.

zT Use T minutes behind GMT (Greenwich Mean Time) as the local
timezone instead of the z parameter value for the file(s)
transferred with this command.

EXAMPLE: sb -k -z300 ESTfile sends ESTfile corrected for creation
in Eastern Standard Time.


6. The W option is supported when receiving files from ZMODEM-90(TM)
program versions after Jan 21 1990.

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Z Transmit files with compression. The ZMODEM receiver must indicate
its ability to decompress received files for this option to take

When sending between Unix systems, files are compressed with 12 bit
Lempel-Ziv compression. Otherwise, packets are transmitted with
Run Length Encoding.

Over slow channels, compression increases the transmission speed of
compiler listings, screen dumps, etc. by up to 50 per cent. LZW
compression is more effective on more types of data than RLE
compression. Some files, including the Personal Computing Magazine
ASCII Test File, speed up by more than an order of magnitude with
either RLE or LZW compression. Heavily encrypted data and
compressed files, including ARC and ZOO archives, do not benefit
from ZMODEM compression.

The situation with fast compressed modems is more complex. The
benefits of ZMODEM compression will depend on the particular
application; try the transfers with and without ZMODEM compression
to determine the most efficient options.

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O Controls OverThruster(TM) operation with the ro command (XMODEM,
XMODEM-1k, and YMODEM) downloads. This parameter should be set
as follows:

CompuServe XMODEM Negative numbers control the number of bytes
added to the window on XMODEM downloads from the CompuServe
Information Service. Larger numbers increase throughput, but
cause improperly interfaced MNP modems on CIS nodes to drop
characters under stress, disrupting the file transfer.

EXAMPLE: dsz pO-512 ro file1.ext

Other XMODEM Positive numbers up to a system dependent value less
than the protocol block size increase throughput. Larger values
induce timeouts and/or retransmitted blocks. The optimum value
must be determined by experiment. 30 to 60 gives best results
with MNP modems at 2400 bps. The optimum value varies depending
on the remote computer, modem(s), system traffic, and the network
node. Performance improvement with high O parameter values is
greater with sluggish networks.

EXAMPLE: dsz pO60 ro file1.ext

EXAMPLE: dsz pO1000 rb -o (EXEC-BBS, MNP 5, 9600

6.1 X/Y/ZMODEM Numeric Parameters

These parameters control XMODEM, YMODEM, and ZMODEM protocol
transfers. They are set with the z px# command available with ZMODEM
flavors of YAM.

EXAMPLE: z pl16384
Forces ZMODEM packet length of 16384 (default packet length is

Their current values can be displayed with a z p command. These
parameters rarely need changing in normal environments.

b If non zero, ZMODEM sends a break when it is sending a file and
receives a retransmission request. This mode of operation may be
used with high speed modems to clear unwanted characters from the
modem's buffer during error recovery. Usually, the modem must be
given a configuration command to make it clear its transmit buffer
when receiving a break signal.

B Sets the duration of the break signal in tenths of a second, default
2 (200 milliseconds).

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c Enables Cybernetic Data Recovery(TM) on XMODEM and YMODEM transfers.
Setting this parameter to 0 accommodates programs with non standard
XMODEM/YMODEM protocols and slightly quickens file transfers. The
default value of 1 provides optimum reliability for XMODEM and
YMODEM transfers with programs that meet the XMODEM/YMODEM spec.

Setting this parameter to -1 disables error checking provided by the
r option.

e If non zero, escape all control characters. This allows ZMODEM
transfers to operate over data PBX and other systems that freak out
when they receive control characters.

d Some operating systems, most notably VAX/VMS, use ^X to stop
programs. ZMODEM uploads consist of a "rz" command to start the rz
program followed by a ZMODEM packet. If the ^X in the ZMODEM packet
causes problems, the zmodem d parameter can be used to delay the
initial ZMODEM packet until the rz program initializes itself. The
zmodem d parameter sets a delay in tenths of a second on ZMODEM
sends (uploads) between the "rz" command and the first packet.

f Flow control mask, only used with Unix/Xenix systems. Setting this
to 0 (the default) disables hardware (RTS/CTS) flow control for
Xenix/Unix systems with broken hardware flow control. On Xenix/Unix
systems where only CTS flow control works properly, set this to 8192
to allow CTS flow control only. If both RTS and CTS flow control
work properly (rare!) you can use a value of -1 to enable both bits.

F Sets the pause after each data subpacket sent with the sz command
when the F option is used, or when failing flow control is detected.
The default value of 1 causes a one tenth second delay.

SEE ALSO: F option On some Unix operating systems the pause will be
rounded up to the next second or two.

l Normally, the ZMODEM "packet length" ("block length") is the file
length. Setting this parameter non zero forces ZMODEM to close a
frame and wait for an ACK after each # bytes (default 0). This
makes ZMODEM behave like XMODEM, YMODEM, or JMODEM, which wait after
each block/packet for an acknowledgement before going on to the next
block. The packet length may be adjusted to prevent buffer overflow
in data PBX systems. The call command resets this parameter to 0.

L (Default 0) If non zero, overrides the nominal length of data
subpackets within each ZMODEM frame. A smaller value speeds error
recovery on noisy lines, a large value (maximum 1024) reduces the
overhead of CRC characters. The call command resets this parameter
to 0.

Please note that streaming ZMODEM has no direct equivalent to
XMODEM/YMODEM/JMODEM block length unless the zmodem l parameter is

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set non zero. In the absence of errors, ZMODEM normally sends the
entire file without pause. If somebody claims ZMODEM's 1024 byte
subpacket length is slowing things down by more than one half per
cent, he doesn't understand ZMODEM and should be ignored.

n Sets the number of NULLS (default 0) sent before each ZDATA frame.
Some buffered modems (Fastcomm) have a firmware bug which loses
characters when changing the direction of transmission. This causes
data frames to fail with a CRC or other error. ZMODEM n parameter
values in the range of 100 to 150 have obviated this syndrome.

P When set to 2 (the default), purge the transmit buffer and force a
receiver response when a CR/LF sequence (indicating a PC-Pursuit
DATA LOSS message) is detected. A value of 1 does not purge the
transmit buffer. A value of 0 disables special processing of CR/LF
sequences received by the sending ZMODEM.

w If non 0, restrict the ZMODEM transmit window to the specified
number of bytes. Setting this parameter to N requests
acknowledgements from the receiver every N/4 characters. Pro-YAM
then waits for acknowledgements from the receiver whenever it has
sent N more characters than it has received acknowledgements for.
This parameter is useful with networks with defective flow control,
and with networks that store an excessive number of characters in
transit. The call command resets this parameter to 0.

W Adjusts the number of characters the ZMODEM receiver will silently
ignore when searching for the beginning of a new frame. This may be
set larger to accomodate networks with excessive in transit storage,
smaller to speed error recovery from long error bursts on direct
connections. The call command resets this parameter to the default

Z Number of minutes (default 0) to adjust the file modification date
when using the Telink or Clink/SEAlink file transfer protocol to
transfer a file between different time zones.

The timeout parameters below may be set lower for faster X/YMODEM
error recovery when transferring files between two micros, higher to
accomodate extremely sluggish systems. Only in pathological cases is
it necessary to modify these parameters. The call command resets
these parameter to their defaults.

p Timeout in tenths of seconds for gaps within a packet (default 100).

r If non zero, remove incomplete files received with a protocol except
those received with the + option (default 0).

R When non 0, limits the number of bytes of file comparision used with
the sz and rz -rr option. This parameter may be set to a value
between 2048 and 32000 (1 billion on 32 bit systems). This

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parameter is given to the receiving program.

EXAMPLE: z pR30000

SEE ALSO: -rr option

s Timeout interval in seconds waiting for XON characters or positive
flow control (default 15). If an XON is not received within this
time, transmission resumes anyway. A value of 0 disables this

t XMODEM, YMODEM, and ZMODEM Receiver timeout in tenths of seconds
waiting for a packet or command acknowledgement (default 100).

T Transmitter timeout in tenths of seconds waiting for a packet
(default 600).
== \

"I don't know what this thing does,
but it's pointing in your direction."
-Dr. Who, from A Usenet Signature

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Hardware Compatibility 41


7.1 Hardware Compatibility Notes

IBM PS/2 Model 50Z Early samples of this machine have a design error
on the motherboard that causes comms programs to lock up the
machine. Replacing the motherboard with a correctly functioning
unit from current production corrects the problem. The part number
of the replacement PS2/50 Z motherboard is 35F5928. (Information
provided by John M. Choma 73047,3566) In the U.S. IBM has
stonewalled on this issue, but in December 1988 agreed to replace
the defective motherboards under warranty.

Zenith Computers Older Zenith computers may need a ROM update to work
properly with interrupt driven programs such as YAM.

NEC Multispeed The NEC Multispeed computer locks up unless STACKS is
set in CONFIG.SYS. In addition, one should disable floppy disk
power save mode, and set popup program memory allocation to 0. For
best results, use the latest NEC software patches to the NEC MSDOS,
and/or use an IBM PC-DOS instead of the DOS supplied by NEC.

EGA/VGA Multimode Boards Some multimode EGA and VGA boards include an
"auto select" feature designed to configure the board to various
display standards using software trickery. In the case of Paradise
VGA and others, this feature causes excessive interrupt latency and
loss of data at high speeds. Disabling the auto select on the
display board corrects this problem.

EGA Wonder The BIOS in the ATI EGA Wonder has been observed to
increase interrupt latency to the dismay of 9600 bps operation on an
8 mHz no wait state AT clone. There has also been a report
(unexplained) that an EGA board has induced line noise in one

Tecmar Graphics Master To use YAM with this display board, give a mode
mono command before running Pro-YAM.

Leading Edge MODEMS and I/O BOARDS Some Leading Edge modems and
interface boards use 8250 UART devices that do not respond correctly
when the software turns the transmitter interrupts on and off. High
performance communications programs such as Professional-YAM require
properly functioning UART chips, such as the National Semiconductor
16450 or 16550A.

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7.2 Brain Damaged UARTS

Omen Technology has received reports of problems with buggy 8250 type
UART integrated circuits in Leading Edge modem boards, serial port
interfaces, and computers. The defective chip logic affects high
performance software. Replacing the buggy chip with a newer chip
(NS16550AFN) corrects the problem.

The UM82450 chip in the Zoom 2400HC also appears to cause problems.
Zoom Telephonics advises that this problem is limited to their old
model. The old model has an external volume control.

You can identify an old chip by inspecting the serial interface board
for 8250 or UM82450 type devices. A service technician or hardware
hacker can help if you are not familiar with reading chip numbers.

Dsz users can identify old chips with the following software command:

EXAMPLE: dsz port 1 speed 2400 p

ZCOMM and Professional-YAM users can look at the printout produced by
the s command; old UART chips register as TYP 0.

The National Semiconductor NS16550AFN is a pin compatible plug in
replacement for 8250 and 16450 serial chips. Omen Technology PCDOS
software enables the FIFO buffer in the NS16550AFN to prevents loss of
data from poorly written device drivers, TSR programs, etc.

We are also using the Goldstar GM82C550 chip with a 9025 date code.
This Goldstar chip is plug compatible with the National chips. No
problems have been discovered with this chip.

The NS16550AFN has better electrical characteristics than the older
UART chips. 386 and fast 286 machines should use the NS16550AFN for
best results. Omen Technology software has been written to allow time
for the older UART chips to operate. However, there is a limit to how
much the software can rearrange chip accesses without resorting to
performance robbing wait loops. Some other software is not as
forgiving of slow chips.

Be sure to ask for the NS16550AFN. It is VITAL to get the National
Semiconductor "AFN" or "AN" chip. Other vendors' chips not mentioned
above won't do. Current Western Digital WD16C550 chips do not
function properly at low speeds.

As of this writing, the Goldstar GM82C550, National Semiconductor
NS16550AN and NS16550AFN are the only plug compatible chips that are
known to work.

The Hayes ESP board comes with two serial ports with NS16550AFN
devices. The ESP definitions for COM3 and COM4 agree with the

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industry standard definitions used by Omen Technology. All option
switches on the ESP board should be OFF except those used to select
the port number (COMn).

The following information comes from a number of people:

"I have located a small dealer in New York who has the cards with or
without the 16550. I believe the price is around $50.00. The company
is RJK Consulting and the number is 718-968-9167. The gentleman to
speak to is a Mr. RJ Kulman. ... I got this information off the
"Interlink" BBS system." Fm: Nick Braak [TRICON] 75156,1254

Fry's - 415-770-FRYS. This is a Silicon Valley electronic department

Jameco Electronics at 415-592-8097 800-538-5000 sells National
NS16550AFN chips mail order (credit card) in small quantities.
Unfortunately, we received a number of reports (none recently) that
their serial i/o card was supplied with the defective WD16C550
soldered in, even when ordered with specific instructions to include
16550AFN chips.

Microprocessors Unlimited, 24000 South Peoria, Beggs, OK. (918) 267-
4961. The price for the chip is $13.50 plus shipping costs.

Consolidated Computers 4 Shoppers Lane Suite 121 Turnersville, NJ
08012 (609)751-9595(voice) (609)751-3843(bbs) (609)751-3840(fax)

Arrow Electronics at 800-932-7769 (516-467-1000).

Willies Computer Software Company: 800/835-4832.

N.B.: Current Western Digital WD16C550 chips do not function properly
at low speeds. This has been confirmed with samples received directly
from Western Digital. WD is aware of this problem, but has not
informed us of a corrected chip.

7.3 Software Compatibility

Some programs and device drivers affecting the operation of PC-DOS may
interfere with YAM, especially when YAM is operating at high baud
rates. Historically, loss and corruption of data have been caused by
memory resident programs. Some of these programs increase interrupt
latency preventing YAM from reading a character from the UART holding
register before the next character comes in on top of it. In other
cases, programs do not properly restore the state of the machine when
they exit from interrupts.

If such a problem is suspected, run YAM without any memory resident
programs or special drivers to locate the source of the problem. Once

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the offending program is identified, a call to the program's vendor
may obtain a corrected version.

The design of memory resident programs is a little known black art.
Subtle bugs, non reproducible interactions, and magic combinations are
commonplace results of attempts to impose various aspects of
multitasking on top of an operating system that was not properly
designed to permit such extensions. Omen Technology Incorporated may
be able to help identify these interactions if provided with the
source code of the offending programs.

Some of the known troublemakers are mentioned below.

Smartdrive This disk cache program (Windows 3.1 version) has been
observed to cause communications errors even when a FIFO UART is

BREAK ON This DOS command causes ^C to be intercepted by DOS at
various, sometimes awkward, times. BREAK ON must be used with
extreme caution as interrupting most programs with ^C compromises
the integrity of the file system. If a program is interrupted by ^C
or Ctrl-Break, the file system should be immediately checked with
CHKDSK. In some cases it may be necessary to reboot DOS with Ctrl-
Alt-Del if DOS runs out of file descriptors. A synonym for BREAK ON

Someday MicroSoft may discover what to do with ^C (DEC figured it
out about two decades ago). In the meantime, we recommend you not
use it. When Professional-YAM starts up, it stores the status of
the BREAK ON flag, then clears it. On Exit, or when calling a DOS
program, YAM restores the BREAK ON flag to its previous state.

Disk Cache Programs Microsoft SMARTDRV.SYS Norton NCACHE Multisoft
PCQWIK Many disk cache programs tie up the computer long enough to
lose modem data. (It only takes a few thousandths of a second!)
Some disk cache programs are worse than others. Some are so bad not
even a FIFO UART can overcome them.

Mouse Drivers Some mouse drivers have been reported to interfere with
file transfers.

DOS append command The DOS append command allows one or more
directories to be partially "grafted on" to a specified directory.
Some DOS system calls "see" files in the new directory, some do not.
This interferes with file transfer options such as -y, -r and -n.
If the DOS append command must be used, use the /x:on switch.

TOPDOS TOPDOS, ver 2.00i by Frontrunner Development Corp., has caused
ZCOMM and other programs to lock up. Disabling TOPDOS restores
normal operation.

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DOS 3.2 DOS 3.2 introduces the concept of a fixed number of interrupt
stacks. The default value chosen is not always sufficient, and DOS
3.2 sometimes prints the infamous Internal Stack Failure message and
cheerfully halts the computer. Adding the line STACKS=20,128 to the
CONFIG.SYS file should correct the problem. Lacking any useful
documentation from Microsoft, you may wish to experiment with
different values.

Extended Memory RAMDISKS Extended Memory electronic disks (ramdisks)
require the 80286 chip to switch in and out of protected mode during
block transfers. A hardware reset pulse is used to switch back to
the "real mode" required for DOS. This causes loss of modem data at
high speeds.

It may be possible to reduce excessive interrupt latency by reducing
the length of protected mode block transfers to 128 or less. In one
instance, replacing the ROM BIOS with a newer version increased the
maximum transmission speed without losing characters to 9600 bps.

This problem has not been observed with expanded memory
(Intel/Lotus/AST/etc.) ramdisks.

The new generation NS16550AN or 82510 serial interface circuits
should be used instead of 8250's for best results at high speed.
The NS16550AN allows operation at a communications speed of 115200
bps compared to 9600 bps (typical) for the 8250 and 16450.

Disk Drivers Disk drivers, especially hard disk drivers for 80286
machines, lock out interrupts for varying periods of time. The
actual interrupt latency depends on the speed of the computer and
the particular BIOS code used. In one case, upgrading to a newer
BIOS allowed operation at 38400 bps, compared to 4800 bps
previously. Such an improvement is well worth the small ($25
typical) cost of a new set of ROM BIOS chips.

DOS 3.x Each new version of PC-DOS adds new features and eats up more
of the 8088's meager resources. DOS 3.2 increases interrupt latency
enough to interfere with YAM's operation at 19200 bps on an IBM PC.
If this is a problem, switching to DOS 2.1 will reduce the interrupt
latency. Replacing 8250 and 16450 serial interface chips with the
new NS16550AN chip allows YAM to operate smoothly at high speeds.

FANSI-Console Versions of this program before 1.07 did not maintain
the pointer to the active display board in the IBM documented memory
location. A DOS mode command may cause YAM to reference the wrong
display adapter address. This caused incorrect sync signals and
possible damage to certain monitors. Current versions (2.X)
increase interrupt latency enough that the serial line drops
characters when the keyboard is touched.

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46 Software Compatibility

Seaware Batch Versions of this program has been known to cause loss of

Spotlight/Lotus Metro This TSR program has been reported to cause
Pro-YAM to lock up.

Pathname Modifiers Programs such as FILEPATH and GLOBALS allow files
to be visible in more than one directory at a time. Such programs
may interfere with security when YAM is restricted, since that
security is based on restricting access to directories. In general,
sensitive files should not be made global when YAM is made
accessible to outside callers.

Pro-YAM may not recognize file names generated by such programs
unless the program traps the DOS FINDFIRST calls as well as the file
open calls.

We have received various reports of strange behavior which have been
traced to filesystem modifications caused by such programs,
including damaged file systems. We recommend such programs be
phased out as soon as possible, as they may not operate at all with
future versions of DOS or distributed file systems.

BRKBOX This program locks out interrupts up to 17 milliseconds while
waiting for the vertical retrace. For a communications program, 17
milliseconds is a very long time, and data will be lost at speeds
above 300 bps.

CGCLOCK Programs such as CGCLOCK.COM use clock interrupts to update a
time display on the screen. Some increase interrupt latency so much
that YAM cannot respond in time to accept characters from the
remote, even at 1200 baud.

Concurrent PC-DOS YAM runs under Version 4.1 of Digital Research
Concurrent PC-DOS (CPCDOS). The - numeric parameter must be set to
0. The CPCDOS "addmem" command should be used to allocate extra
memory if DOS Gateway are to be used.

ANSI.SYS YAM uses direct keyboard input from the ROM BIOS because the
DOS keyboard input calls do not handle Ctrl-BREAK properly. As a
side effect, keyboard keys redefined by ANSI.SYS have no effect on
YAM's operation. It is possible to program some of the keys to call
YAM with arguments. The following file, reassigns ALT-C, ALT-H, and
ALT-V to execute the commands shown below. The $ character
represents ESCAPE.

$[0;46;"cd \tmp";13;"YAM call -200 cbbs-r";13p
$[0;35;"YAM call host";13p
$[0;47;"cd \tmp";13;"YAM call cissig";13p

YAM uses the ROM BIOS CRT functions and direct output to the

(C) 1990 Omen Tech Inc Chapter 7 Software Compatibility

DSZ Manual Addendum Line Printer Draft
Software Compatibility 47

display, bypassing any processing provided by ANSI.SYS. Perhaps
someday Microsoft will enhance ANSI.SYS to make it useful for
programs like YAM ...

PRINT.COM Once the DOS PRINT program is memory resident, file
downloads at high speeds (38kb on a PC) suffer from interference,
even if a file is not currently being printed.

With certain printers, the DOS PRINT command will preempt the
running program for several seconds at a time. These "swapouts" can
be confusing when you are accessing an interactive application.
They may interfere with file transfers, especially if the remote
program uses "tight" timing. If this happens, PRINT should be
suspended during file transfers. Operation of the PRINT command
does not appear to cause loss of data downloaded from timesharing
services at 1200 bps, as long as the interruptions last less than
ten seconds. Perhaps IBM or Microsoft will someday fix this bug in
the DOS PRINT command. PRINT should not be invoked from YAM for the
first time as DOS memory allocation will become fragmented.

If PRINT or some other spooler is outputting to a serial port using
the BIOS INT 14h serial port driver, YAM's "!~subprogram" command
will redirect the printer output to the remote and thus should be

SWITCHAR = - YAM will work properly when the DOS switch character is
set to "-", allowing Unix style pathnames. The - numeric parameter
must be set non zero to allow YAM DOS Gateway to use / to delimit

It may be necessary to remove this line from CONFIG.SYS and reboot
DOS before using the IBM dump and restore commands.
N.B.: DOS 3.0 does not support SWITCHAR in the config.sys file. A
short program, DASH, will set switchar to -. It prevents many
oaths. Microsoft has removed all SWITCHAR support in DOS 5.0. So
much for POSIX compliance.

This manual is Copyright 1992 Omen Technology Incorporated, All Rights

It was formatted 11-3-92.

(C) 1990 Omen Tech Inc Chapter 7 Software Compatibility

DSZ Manual Addendum Line Printer Draft
48 Software Compatibility


(C) 1990 Omen Tech Inc Chapter 8 Software Compatibility

Chuck Forsberg


(C) 1992 Omen Tech Inc Chapter 8 Cross Reference Index

Version 18.00 TurboDial 2.36 Line Printer Draft
Cross Reference Index

50Z 41 file name override 24, 26
7 bit data 29 file transfer 24, 24, 25, 26
80286 45 file transfer packet length 32
8250 UART 42 Flow Control 18, 22, 31, 35, 37,
ANSI.SYS 46 39, 40
append 29 frame length 38
append DOS command 29, 44 front end 30
batch file transfer 24, 25, 26 GEnie 16
baud rate 46 graphic file transfer display 3
BIX Timesharing Service 16 handshake 18
Block length 7, 38 handshake command 21
Break 37 hard disk 45
BREAK ON 44 Hayes ESP board 42
Byte Information Exchange 16 IBM PS/2 Model 50Z 41
Cache, disk 44 image option 32
carrier detect 21, 23 interrupt latency 45, 46
Clear to Send 21, 22 Lempel-Ziv 36
Clink 24, 26, 39 Lotus Metro 46
collision 30 LZW 36
comm port 22 minirb program 13
compression 6, 36 Moby Turbo 32
CompuServe 25 MobyTurbo 6
Concurrent PC-DOS 46 modem port 22, 23
control character escaping 30 MODEM protocol 25, 26
CPCDOS 46 Mouse Drivers 44
CPMEOF 10, 10, 11, 26 Multispeed 41
CR 14, 29 NEC Multispeed 41
Crash Recovery 5 newline 29
CRC-16 24, 26, 30 no carrier detect 21, 23
CTS 21, 22 ONAME= 26, 27
Cybernetic Data Recovery 38 options 24, 24, 25, 26, 29
data PBX 30 OverThruster 9, 11, 25
Data Set Ready 21 packet length 38, 38
date stamping 5, 9 PAD 19
DCD 21 pathname override 24, 26
delete 34, 35 pathname, full 30
directory specification 24 pathnames, received 24, 25
disk cache 44 pathnames, transmitted 26, 26
DOS 3.2 45, 45 PBX, data 38
DOS append command 29, 44 PC Pursuit 19
DSR 21 PC-Pursuit 39
EGA Auto-select 41 Performance log 34
Emacs 18 port command 22
erase 35 portx command 23
estimate command 21 PREFIX= 26
Extended memory 45 PREFIX=p 27
FANSI-Console 45 printer spoolers 47
Fastcomm 39 PS/2 Comm Ports 22
FIDO 24, 26, 39 Qmodem-G 12, 32
file date 5, 9 RAMDISK 45
file download 14, 14 rb command 24

(C) 1992 Omen Tech Inc Chapter 8 Cross Reference Index

Version 18.00 TurboDial 2.36 Line Printer Draft
Cross Reference Index

rc command 24 ZMODEM 4, 25, 26, 29, 35, 37
Relaxed XMODEM 11 ZMODEM protocol 26
Relaxed YMODEM 11
remove 34
RLE compression 36
ro command 24
rx command 25
rz command 25
sb command 26
SEAlink 24, 26, 39
security 24, 26
Serial Number 34
SlugBait 34
Smartdrive 44
Spotlight 46
Stream_LF record format 32
Streaming XMODEM 12
Subpacket length 7
sx command 26
sz command 26
Telenet 19
Telink 39
term function 34
Terminal Multiplexers 8
Thedraw 3
time zone 5, 9
Timing 40
transparency 30
Unix 13
unlink 34
VGA Auto-select 41
view 34
VMS 15, 32
VMS Stream_LF record format 32
window size 19, 35, 39
X.PC 10, 11, 31
XMODEM 10, 10, 18
XMODEM Protocol 25, 26
XMODEM-1k 10
XOFF 18, 40
XON 18
YMODEM 9, 12, 18, 24, 26
YMODEM-g 11, 24, 25, 31
Zenith 41

(C) 1992 Omen Tech Inc Chapter 8 Cross Reference Index

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