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SZMODEM ver 1.50
-----------------
By Scott M. Baker
What is SZModem?
SZModem is a zmodem-compatible protocol with a few added features. It
is fully compatible with normal zmodem, but adds special capabilities both
when talking to normal zmodems and while talking to other copies of
SZModem.
The main idea behind SZModem is that you should be able to do other
things while the transfer is taking place. Rather than have your computer
tied up for an hour downloading a file, you can move around in the SDOS
window and do directory maintenance, etc...
What will it do?
While SZModem is transferring a file, you may do the following:
Connected to a "normal" zmodem such as DSZ.
- List files marked for upload
- List files received as they are received
- Uses SDOS (simulated dos) to view directories, copy files,
etc while the transfer is taking place.
- View file contents as the file is being received (good for
text files)
- Play single-player games while transferring.
- Built in mail reader allows sysops who are using a BBS program
that uses FIDO message formats to read mail while transferring.
Connected to another copy of SZModem.
- All of the above capabilities
- A "chat" mode allows the two sides to talk to each other.
- Play multiplayer games such as Four-In-A-Row
- The sender will automatically send a "advance transfer list"
listing the files to be sent. This way, the receiver knows
what he is receiving.
- SZTurbo option allows SZModem to pass flow control characters
unaltered across the modem. This allows for up to a four percent
effeciency gain over normal Zmodem.
- Ability to use large zmodem packet lengths - up to 2048 bytes
at 2400 baud and 4096 bytes for higher speeds.
- LZW compression routines allow significant efficiency improvements
for text files, ASCII data, etc.
Command specifics
-----------------
F1 - Transfer (send) list
This command will produce a windowed list of the files that have
been sent, aborted, marked for sending, etc. Included is the file
name, size, and all other pertinant information. You may use the up
and down arrows if necessary to scroll the list.
Pressing F1 again (i.e. while you are already in TLIST) will toggle
between the file-information list and the file-description list.
F2 - Received file list
This command will produce a listing of the files are have been
received. Similar to the "F1" list above, you may use the up/down
arrows to scroll the list. THe list is updated as files are received.
If you are connected to another copy of SZModem, the sender
will transmit a special "advance transfer list" containing a listing
of the files that will be sent. This list will be displayed with the
F2 command.
As with F1 above, pressing F2 again will toggle betweem the file
information display and the file description display.
F3 - SDOS (simulated dos)
SDOS is a special dos emulator that lets you perform a variety of
operations while the transfer is taking place. You can copy/move files,
list directories, change attributes, etc - most of the common things you
do with normal dos.
You may get a listing of supported SDOS commands by typing "HELP"
at the dos prompt. Typing help with a command name (i.e. HELP DIR) will
display help for that specific command.
Most SDOS commands are pseudo-multitasked as to not interfere with
the transfer, although with high speed modems (i.e. 14,400 baud and
up) the transfer may slow down during disk-intensive operations.
F4 - COMM PARAMS
This command will pop up a display of the current communications
parameters - baud rate, parity, buffer status, etc. It can be useful in
debugging difficulties.
F5 - VIEW
Pressing F5 will allow you to "view" the transfer as it is taking
place. You will actually see the characters of the file, zmodem
handshaking, and line noise as it takes place.
If you press F5 while you are already in the view window, you will
toggle the view mode. There are 6 different modes. Here is a listing:
1 - Direct ascii printing of characters as they are sent or recvd
2 - Ascii print only RECEIVED characters
3 - Ascii print only TRANSMITTED characters
4 - HEX printing of transmitted and received characters
5 - HEX printing of only received characters
6 - HEX printing of only transmitted characters
The modes will cycle one at a time each time you press F5. Initially,
this whole idea of the view mode was simply a debugging option for me,
but I figure some users might like to watch the transfer taking place.
F6 - MESSAGES
The message display shows a log of the various messages that SZModem
displays on the screen - CRC Error, Waiting for ZRINIT, stuff like that.
F7 - CHAT
This command can only be used when two SZModems are connected to
each other - it won't work with a normal Zmodem. The chat mode allows
you to talk to the user at the other end of the transfer. The screen
will be split into two windows - one for what you type, one for what
the other guy types.
Pressing CTRL-G will page the other user if he isn't at his
terminal. The page will beep for thirty seconds, one beep every
three seconds.
F8 - GAMES
The games menu will be displayed and you can select a game to play
while the transfer is taking place. There are two kinds of games -
single player games which to play by yourself and multiplayer games
in which you play against the guy on the other end.
The single player games may be player no matter what you are
connected to, but the multiplayer games require you to be connected to
another copy of SZModem.
F9 - MAIL READER
This is a feature designed to be used by the sysops of Bulletin
Boards which have a FIDO compatible message format. (See the below
section on "The Mail Reader" for info on setting up this feature)
By pressing F9, the sysop will be allowed to read messages in the
chosen message base. There are several additional UNLISTED keys available
in this window:
"N" Move forward one message
"P" Move backwards one message
<Space> If the message is more than one screen, this will scroll the
window.
F10 - EXIT
This brings you the exit option which aborts all files and returns
you to the DOS prompt.
COMMAND LINE OPTIONS
--------------------
SZModem was designed specially to have a command line similar to the
popular DSZ Zmodem protocol. This way users with an understanding of DSZ
can easily set up SZModem. The options area as follows:
"SZMODEM <options> <transfer type> <filenames>"
Options can be any one of the following:
"PORT x" specifies using comport x. (i.e. "PORT 2" would use com2)
"SPEED x" specifies the baud rate (i.e. "SPEED 2400 would use 2400 baud)
"IRQ x" specifies a nonstandard IRQ. (NOTE: please specify the
address in DECIMAL, not HEX). You must supply BOTH an IRQ
and an address to use nonstandard ports.
"ADDR x" specifies a nonstandard ADDRESS. (NOTE: please specify
the address in decimal, not hex). You must supply BOTH an IRQ
and and address to use nonstandard ports.
"/NOLOG" disables logging to the "SZMODEM.LOG" file.
"/M" monochrome mode.
"/DORINFO x" Specifies the node number of a dorinfo.def file to grab the
user's name from. If you specify this option, SZModem will
load in the dorinfo, get the user name, and display it in
the screen so you know who is downloading. (I.e. specifying
"/DORINFO 1" would load in "DORINFO1.DEF")
"/INSIZE x" Specifies the size (in bytes) of the internal comm input
buffer. (Note: not used if using fossil)
"/OUTSIZE x" Specifies the size (in bytes) of the internal comm output
buffer. (Note: Not used if using fossil)
"/SZPATH x" Specifies a path to which the SZXFER$.LST and SZMODEM.LOG
files will be written to. If not specified, the files will
be created in the current directory.
"/DELAYTIME x" SZModem by default will wait 5 seconds at the end of
transfer for a keypress to before exiting. BBS sysops may
wish to lower this time for faster operation. The "x"
specifies the default time to delay, which may be
from 0-30 seconds. (NOTE: /DELAYTIME can be abbreviated
/DT)
"/SZTURBO" Causes SZModem to attempt to use the SZTurbo option if
possible. If SZTurbo is to operate, both sides must have this
option set. See "SZTURBO" below. (NOTE: /SZTURBO can be
abbreviated /SZT)
"/NBS" This stands for "normal block size". By default, if two
SZmodem's are connected, they will allow the Zmodem packet
length to rise to 2048 bytes/packet at 2400 baud or 4096
bytes/packet for higher speeds. Specifying "/NBS" will force
SZModem to use block lengths of 1024 bytes or less.
"/NORBL" Will cause your copy of SZModem to refuse to accept LARGE
format (i.e. embedded file description info) advance transfer
lists.
"/NOSBL" Will cause your copy of SZModem to refuse to send LARGE
format (i.e. embedded file description info) advance transfer
lists.
"/FL" This will cause SZModem to create an additional log file
called "FILELOG.TXT". This log is intended to allow users to
keep a record of files they receive. It only logs RECEIVED
files and it includes the name, size, and optional description
of the file.
"/NOPAGE" This will prevent another copy of SZModem from paging your
copy.
"/FILEDESC x" This specifies an additional FILEDESC list of file
descriptions. "x" is the path and filename of the file. See
"Large Advance Transfer Lists" for more info.
"/CHECKSNOW" If you are using a CGA card and it gets snow, try using this
option.
"/NOCOMP" This will force SZModem to disable file compression.
"/FIDOAREA x" Specifies a fido-format message base that SZModem's built
in mail reader will allow the sysop to read while a transfer
is taking place. The "x" is the path. (i.e. "/FIDOAREA
I:\BINKLEY\MESSAGES").
"/EGA" If you have an EGA or VGA display, this switch will enable the
43/50 line modes.
"/DL" This option will cause SZModem to create a DSZ.LOG file. This
file will contain a DSZ-style log. This option may be used
with BBS programs that require a DSZ.LOG file to operate their
external protocols. SZMODEM also will enable the DSZ.LOG if
the environment variable "DSZLOG=xxx" is used.
"/CFGPATH x" Specifies a path to where the configuration file (SZMODEM.CFG)
can be found. "x" is the path with or without a trailing
backslash. It doesn't matter.
"/HARD" This turns on HARD flow control. This means that when your
modem drops CTS, SZModem will stop transmitting until CTS
is raised again. This option is frequently used with high
speed modems and/or locked baud rates.
"/SOFT" This is similar to the above HARD flow control, but uses
ascii characters to control the flow. Namely, the Xon and
Xoff characters - when XOFF is received, SZModem will stop
transmitting and when XON is received, SZModem will resume.
(Note: SZTURBO mode is not available with this type of
handshaking)
"/LOCK x" Specifies a locked baud rate. The com port will be set to
the baud rate specified by this parameter, and the baud rate
specified by "BAUD x" above will be used for estimation
purposes.
Transfer type may be any one of the following:
"RZ" receive zmodem file(s)
"SZ" send zmodem file(s)
Filenames are interpreted as follows:
Send mode: Multiple filespecs may be present. Wildcards are allowed.
Recv mode: A path to the receive directory is expected. No filenames
are necessary. If you add a filename, SZModem will strip it
from the string and ignore it.
EXAMPLES:
---------
"SZMODEM PORT 4 SPEED 9600 SZ \UPLOAD\*.ZIP"
Send all the .ZIP files in you upload directory using COM4 at
9600 baud.
"SZMODEM SPEED 1200 RZ"
Receive files at 1200 baud using COM1. Store them in the current
directory.
"SZMODEM PORT 3 RZ \TEMP"
Receive files at 2400 baud using COM2. Store them in the "\TEMP"
directory.
Files
-----
SZMODEM.EXE - The executable code for SZModem. This is what you
need to call to execute the protocol. Memory
requirements should be from 130-170k depending
on how you have szmodem set up.
SZCONFIG.EXE - This program allows you to set a variety of
SZModem's default options and store them in the
SZMODEM.CFG file.
*SZMODEM.CFG - This file is created by the above SZCONFIG.EXE. It
contains default option values for various SZMODEM
parameters. Basically, you can use SZCONFIG.EXE to
put the options here rather than specifying them on
the command line.
SZMODEM.DOC - These docs that you are reading.
SZMODEM.TRV - A "trivia" file which lets you play trivia during
SZModem.
SZMODEM.HLP - An ASCII help file which contains help on the SimDos
commands.
*SZMODEM.LOG - A log created which contains a listing of files
transferred, dates/times, etc. May be disabled
with the "/NOLOG" option. You may set the
path this file will be placed in with the "/SZPATH"
option.
*DSZ.LOG - If the /DL parameter was specified, this file will
be created to allow for compatibility with the
popular DSZ protocol.
*SZXFER$.LST - This is the "advance transfer list" file. It is
created by the sender and if the receiver is also a
zmodem, is sent to so the receiver may have a list
of files to be received ahead of time.
*FILELOG.TXT - If the "/FL" parameter is specified, this will will
contain a listing of all files received (downloaded)
by SZModem. Included is the file name, size, and
optional description.
(* Denotes file is CREATED by SZModem, not distributed with the package)
Hardware Requirements
---------------------
Processor: 10mhz 80286 or greater suggested, but will work with any
IBM-PC compatible machine.
Display: Anything should work
Memory: SZMODEM.EXE 130-107k
Nonstandard port addresses:
---------------------------
You must use the "IRQ x" and "ADDR x" parameters to specify a
nonstandard com port. Numbers must be in DECIMAL, not HEX. DO NOT
specify a "PORT" if you use nonstandards.
For example:
"SZMODEM IRQ 2 ADDR 1016" would cause szmodem to use whatever port is
at IRQ=2 and ADDRESS=1016 ($3F8 hex)
The Overlay Version
-------------------
There is now one and only one version of SZMODEM.EXE distributed
in the package. Before, we had three seperate versions configured for
various memory requirements, but from now on, there is only one.
For those of you who are curious, the version of SZModem
distributed is the overlay one (used to be SZMODOVR.EXE). I did this
since the old SZMODEM.EXE was gobbling up too much memory to be
useful and the SZMODSML.EXE version wasn't saving enough space to
justify it.
Flow Control, Handshaking, High-Speed Modems, Locked baud
---------------------------------------------------------
SZModem includes two command line options for controlling computer-
to-modem handshaking. This handshaking allows the modem to send some form
of signal to SZModem to tell SZModem to stop sending data if the modem's
buffer becomes overflowed.
If you are using a 2400 baud modem or lower, and are sending data to
this modem at 2400 baud, then no handshaking options should be necessary.
But, if you are using a high speed modem at a locked baud rate, handshaking
is VERY necessary.
The are two type of handshaking: HARD and SOFT. Hard handshaking uses
the CTS/RTS lines (i.e. wires) between your modem to control data flow and
is considered the better of the two. SOFT handshaking uses two special
ASCII characters, XON and XOFF, to control handshaking. Basically, you have
to match SZModem to the type of handshaking your modem uses.
To enable HARD handshaking, specify the "/HARD" option on the command
line. To enable SOFT handshaking, specify "/SOFT". You should only specify
one, not both.
Consult your modem manual, bbs software docs, etc for more
information on handshaking.
SZTetris!
---------
New with version 1.50, a game called "SZTetris" has been included in
the games (F8) menu. The game is your standard Tetris type game. You can
use the arrow keys to move the falling blocks, the J,K,L keys, or the
keypad w/numlock (4,5,6,2).
The game is in its eary stages and may still have a couple of
glitches in it.
NOTE: SZTetris is a processor-speed hog. If your running szmodem
at 19.2kbaud at a low cpu speed (8mhz or lower), you may get errors. On my
25mhz 386, however, I have tested szmodem at 19.2kbaud while playing
sztetris with no troubles whatsoever.
SZTurbo
-------
SZTurbo is an option that will allow you to improve file transfer
efficiency by as much as four percent. To explain how SZTurbo works,
I must discuss a little about how Zmodem itself works.
In the Zmodem specification, certain bytes cannot be transmitted
freely across the modem connection. These bytes are XON, XOFF, ZDLE (a byte
very important to Zmodem), and a few others. If for example, an XOFF
was transmitted across the modem link, it could cause difficulties.
Although these bytes may not be transmitted, they do occur in binary
files so Zmodem must find someway to transmit them. What it does is send
a ZDLE followed by byte (i.e. the XOFF) XOR 64. This translates the illegal
character to a harmless ASCII letter that may be freely sent across the
modem link.
A few quick thoughts and you should be able to see that every time
one of these "illegal" characters are encountered, two bytes (The ZDLE
and the character XOR 64) must be sent. Sending two characters instead of one
obviously adds overhead to the transfer, slowing it down.
It turns out that most of these "illegal" characters are not illegal
under most situations. Almost all current moedems are able to transfer
XONs,XOFFs, etc just fine. So basically what SZTURBO does is send these
illegal characters just like any other character. Here's a quick diagram
to help explain this:
Characters sent Character(s) sent
Character in File without SZTurbo with SZTurbo
----------------- --------------------- ----------------
ZCHAT (#14) ZDLE (#24) "N" ZDLE (#24) "N"
DLE (#16) ZDLE (#24) "P" DLE (#16)
XON (#17) ZDLE (#24) "Q" XON (#17)
XOFF (#19) ZDLE (#24) "S" XOFF (#19)
ZDLE (#24) ZDLE (#24) "X" ZDLE (#24) "X"
As you can see, SZTurbo shortens the sequences for DLE, XON, and
XOFF from 2 characters down to one character. While this does not seem like
much, it can add up to a four percent efficiency gain. When you're paying
the long distance bill, you'll appreciate this.
Specifying "/SZTURBO" on the command line will cause your copy of
SZModem to "attempt" to engage the SZTurbo option. SZTurbo is only
available if both sides have the option specified.
Large Advance Transfer Lists
----------------------------
Starting with this version, there is support for a "large" advance
transfer list. The main difference between the normal list and the "large"
list is that the large list contains optional file descriptions as well
as the name, date, etc. The receiver or sender may browse through these
descriptions while the transfer is taking place.
The problem is, SZModem can't just make up these descriptions
itself. The sender must somehow provide SZModem with the descriptions. If
the sender is a bbs program, then the descriptions are available from
the BBS's file catalog. The descriptions must, however, still be converted
to a format that SZModem can understand.
SZModem will look for file descriptions in the file "FILEDESC.TXT"
(or "FILEDE1.TXT", "FILEDE2.TXT", etc if you are multinode) in the
directory specified by the /SZPATH option. This file follows a simple
format. It is plain ASCII with each line of the file corresponding to a
file. The filename starts at column 1 and the descriptions starts at
column 15. For example:
::-- Col. 1 ::--- col. 15
:: ::
\/ \/
SZMOD120.ZIP Zmodem protocol with Chat, Simdos, etc
GALWAR75.ZIP Galactic Warzone version 7.5
DOORDR30.ZIP Doordriver door support routines
MACH10.ZIP Mach-10 bbs
When SZModem loads, providing the /NOSBL switch is not specified and
providing this file exists, the descriptions will be searched, loaded, and
sent to the receiver providing his /NORBL switch is not set.
As you have probably noticed, this format is probably not what your
bbs uses. Since I don't have information on the file formats of most BBS
packages, I had to make do with this "generic" format. Hopefully, some
bbs sysops who are programmers can write a utility to grab the necessary
descriptions out of their file catalogs and throw them into the
FILEDESC.TXT file.
Note: The FILEDESC.TXT file may be named FILEDE1.TXT or FILEDE2.TXT
depending on your configuration. The /DORINFO switch will determine which
.TXT file SZModem will look for. If no /DORINFO is specified, FILEDESC.TXT
will be used. If /DORINFO 1 was specified, FILEDE1.TXT will be loaded.
Examples:
Filedesc file used
------------------
SZMODEM SZ FOO.BAR FILEDESC.TXT
SZMODEM /DORINFO 1 SZ FOO.BAR FILEDE1.TXT
SZMODEM /DORINFO 2 SZ FOO.BAR FILEDE2.TXT
SZMODEM /SZPATH \protocol SZ FOO.BAR \PROTOCOL\FILEDESC.TXT
SZMODEM /SZPATH \protocol /DORINFO 1 ..... \PROTOCOL\FILEDE1.TXT
Now, a quick word on the /NOSBL and /NORBL switches. If you specify
/NOSBL, your copy of SZModem will not send the description info under any
circumstances. If you specify /NORBL, your SZModem will not allow another
SZModem to send the description info under any circumstances. Example:
Sender Receiver Desc info sent
------------------ ------------------- --------------
SZMODEM SZ ... SZMODEM RZ ... *YES
SZMODEM /NOSBL SZ SZMODEM (anything) NO
SZMODEM (anything) SZMODEM /NORBL NO
(* only if FILEDESC.TXT, FILEDE1.TXT, etc exists on sender side)
Additional FILEDESC files may be specified using the /FILEDESC
option. Use the format "/FILEDESC x" where "x" is the path and filename
of the additional list to search. You may add as many of these additional
lists as you wish. (NOTE: Operation will occur faster if all of the
descriptions are in one file rather than many file)
File Lists
----------
If you specify @<filename> on then command line, <filename> will be
opened and any file paths contained within will be sent. For example,
suppose a textfile, "TOSEND.TXT" contained the following:
\DOWNLOAD\SZMOD120.ZIP
\MACH10\WELCOME.TXT
\GALWAR\TWARS.EXE
If you called up SZModem with the command line "SZMODEM SZ
@TOSEND.TXT", SZModem would then send the three files listed above. This
allows you to specify many different filenames in an ascii file rather
than have to fit them all on the command line.
You may also specify SZModem parameters in these "file lists". You
could specify "/DORINFO 1 /SZTURBO /SZPATH \protocols", etc and then call
it up with the "@" sign rather than having to put all of those options on
the command line.
File Compression
----------------
SZModem now includes a LZW compression module which can compress
the file data as it is being sent. Although for binary and compressed data,
the LZW compression will make little difference, it can create substantial
compression for ASCII data, text files, word-processor files, etc.
By default, compression is automatically enabled for any file
with an extention other than ZIP,ZOO,PAK,ARC. If both SZModems support file
compression and there is memory for the 21k hashing table, compression
will occur on a block-by-block basis. The "packet size" display will
reflect the size of compressed data subpacket and the (real) size of the
uncompressed data in paranthesis (i.e. "Packet size....: 1398 (2048)" would
indicate that 2048 bytes were compressed into 1398 bytes).
To use the compression algorythm, an extra 21k of data space is
necessary for a special "hashing table". If there is not 21k of memory
available for SZModem, the hashing table will not be created, and
compression will be disabled.
The command line switch "/NOCOMP" may be used to force compression
to be disabled.
The Mail Reader
---------------
SZModem is equipped with a mail reader capable which allows the
sysop to read any messages in a fido-format message base. This feature is
only useful for BBS systems or mail point systems, and has no particular
interest to users.
So far, SZModem can only handle one message area. I am making
provisions to add support for more area, but that will be in a later
version.
To enable the mail reader, add the "/FIDOAREA x" switch into the
command line, with "x" being the path to your fido area. (i.e. "/FIDOAREA
I:\BINKLEY\MESSAGE"). No trailing backslash is necessary.
Then, you may use the F9 key to enter the mail reader. The "N"
and "P" keys will move you forward or reverse in the area and the SPACE
bar will scroll a message.
Benchmarks
----------
The following chart compares the CPS readings for some various
protocols. SZMODEM ver 1.31 was used for the SZMODEM tests and DSZ1612
was used for the DSZ Zmodem, Xmodem, and ymodem tests.
The tests were performed between two AT-class machines running
at 8mhz.
SZMODEM SZMODEM DSZ DSZ DSZ
Filename File Size w/SZTURBO ZMODEM XMODEM YMODEM
------------ --------- --------- ------- ------ ------ ------
SYSOP.DOC 18357 399 390 235 200 200
MACHCTL.ZIP 20643 236 232 234 201 200
MOUSE.COM 14249 284 274 234 202 199
SIMCGA.ZIP 2406 233 233 235 200 200
Revison History
---------------
Version 1.00 - First public BETA release.
This software has not been tested very well at
this point. There may be trouble with high speed
modems, COM3/4 conflicts, etc. Please report any
bugs to my bbs listed below.
Version 1.01 - Fixed a problem that caused the DORINFO display
that caused the users last name and city to be
displayed. Now, the user's full name and city is
displayed.
Version 1.02 - Added the "/SZPATH" option to allow the user
to specify what directory the SZMODEM.LOG and
SZXFER$.LST files will be placed in.
Fixed a bug which was causing runtime error
2 that had to do with the SZXFER$ list.
Added "/DELAYTIME" option to specify time that
SZModem will delay after a transmission is completed,
waiting for a keypress.
The CHAT indicator will now blink when a remote user
is typing in chat and the local user is in another
window.
Version 1.10 - Added FREE and SIZE commands to simdos. See the
SZMODEM.HLP file for more information.
Various cosmetic improvements.
Made the SIMDOS parser a bit more intelligent. It can
now process commands without spaces between parameters
such as "DIR/W" or "CD..".
Added DELNUL command to delete zero-length files.
SZModem now displays a small message if the user does
not specify SZ or RZ. This helps new users to know
they do in fact need to specify SZ/RZ.
SZModem /HELP command now available. Displays a small
help screen of some of SZModem's command line
parameters.
Major revisions to the actual ZMODEM transfer code.
CRC32 now used rather than CRC16 and the block check
display now correctly reflects this. (Note: If the
sender requests CRC16, the receiver will be stuck with
CRC16 also)
Error correction will now function properly in both
CRC32 and CRC16 modes.
"Last frame" display on receiver now functions
properly.
Default delay time changed from 10 seconds to 5
seconds. (See /DELAYTIME above)
Added an overlay version of the program (SZMODOVR.EXE)
to allow for systems with less available memory.
Version 1.20 Added SZTurbo option to increase transfer efficiency
by as much as 4%. See the SZTurbo section of this doc
for more info.
Added "/NBS" option to allow users to restrict
SZModem's block size down to the standard 1024 bytes/
block like normal zmodem.
The minor version identifier (i.e. .20) is now sent
along with the major version identified (i.e. 1)
Message screen (F6) code revised to reduce flickering
and add smoother scrolling.
Two ZChallenges are now sent between copies of SZModem
to allow for additional information to be passed -
version numbers, flags, etc.
Added provisions for LARGE Advance transfer lists.
(See Above). The new large list allows the sender to
send file descriptions along with the usual file info.
Fixed the TLIST and RLIST displays so they scroll the
corrent number of lines.
Added "/FL" switch for a received file log.
Version 1.21 Added more information to the log display.
Fixed a bug which caused file descriptions to be
garbage when receiving file from a normal Zmodem.
Added ability to process file lists. (See above:
File lists)
Added /FILEDESC option to specify additional
filedesc files.
Added the /CHECKSNOW option to enable snow checking.
Fixed the DELNUL command in SDOS so that it does not
try to delete files as they are being received.
Control-Break is now trapped and no longer aborts the
program.
Added CTRL-G option to allow users to page in chat
mode.
Version 1.30 Default internal output buffer size has been
changed from 256 bytes to 512 bytes.
Revised overlay code so hopefully SZMODOVR.EXE can
be used by multiple nodes on a network without
difficulty.
Added file compression capability. LZW compression
routines will speed up the transmission of most
non-compressed data.
Default internal input/output buffer sizes
re-adjusted to 1k and 6k respectively.
Added a simple sysop mail reader to allow the sysop
to read mail while transfer is in progress.
Fixed a bug with the ZChallenges that caused SZModem
to not abort if the Zchallenges were not responded
to.
Included a "Small" version which is even smaller than
the overlay version. Left out are the games module
and the mail reader module. The filename is
SZMODSML.EXE.
Added a zip viewer to SimDos. The command "ZIPVIEW
<filename>" will display the file directory of a
zip file.
Version 1.31 Added DEBUG command to simdos to allow users to
browse through files in a hexadecimal mode.
EGA/VGA 43/50 line modes are available with the
/EGA command line switch.
If SZTURBO is enabled and soft (Xon/Xoff) flow
control is enabled, the SZTURBO will automatically
be disabled.
Added SZCONFIG.EXE configuration utility.
/DL command line will enable a DSZ.LOG file log
for compatibility with various bbs programs.
Version 1.40 REMOVED FOSSIL SUPPORT
There was just too little demand for use of the fossil
interface routines and considering the overhead it was
adding (an additional jump and compare for every
async function can add up), the code was removed and
the INTERNAL routines are now accessed directly.
Major serial code revisions. On locked baud modems,
the keyboard I/O shouldn't slow down quite as bad
as before. Chat may still appear choppy though.
Added a DORINFOx.DEF path to SZCONFIG.EXE. You may
now set the path that SZModem will look for
DORINFOx.DEF with SZCONFIG.EXE.
Added CFGPATH parameter to specify path to
the SZMODEM.CFG file.
Version 1.41 Added information on HandShaking to docs.
Added handshaking options to SZCONFIG.EXE.
Added locked baud capabilities with the "/LOCK"
parameter.
Version 1.42 Fixed minor bug with command line options. Command
line options now override environment vars at all
times (i.e. SZMODEM port 2 would override SET DSZPORT=
1)
If transfer times out, szmodem will return errorlevel
of 1.
DSZLOG is now appended to rather than rewritten
by SZMODEM.
Fixed problem with /CFGPATH causing files to be
written to the root directory.
Version 1.43 Added abbreviations "/SZT" for /SZTURBO and "/DT" for
delay time.
Added the "BROWSE" command to simdos. Browse will let
you scroll up and down within a file.
Fixed problem with received file path.
Altered some code in the Z_challenge routine to
compensate for a bug in QMODEM (Qmodem does not
understand Z_Challenge requests which caused
szmodem to abort the xfer)
Altered some code to hopefully fix a glitch or
two at high speeds. (14,400 and 19,200 baud may
have gotten some aborts due to "header is fubar"
messages. This should now be fixed)
Version 1.44 Some cosmetic improvements and minor bug fixes.
Added registration request.
Added support for nonstandard IRQ/address
Version 1.50 Added SZTETRIS! Available from the games menu!
default delay time lowered to 2 seconds.
Replaced the more-or-less meaningless ZFRAME
status item with a realtime-updated CPS display.
With the internal tetris, SZMODEM.EXE got too big
to be usable; with some efficiency fixes, SZMODOVR
and SZMODSML became about the same, so now we only
distribute one version.
The SZXFER$.LST transfer list is now deleted after
szmodem is completed.
Shrunk the size of the control-key line at the
bottom of the screen a bit to provide for additional
screen space in sztetris, simdos, etc. Two extra
lines can really make a difference!
Credit to Other Authors
-----------------------
1) Turbo Pascal Zmodem Source. This software was built up from a rather
buggy source code of Zmodem in turbo pascal. The code did not list
an author.
2) ASYNC11 package by Mark Shultz. This excellent package provides
for portions of SZModem's async support. The fossil interface is
written by myself, but I also integrated these ASYNC11 internal
routines to provide support for users without fossils.
Registration
------------
SZModem represents many hours of programming and debugging. If you find
this software useful, then please register your copy to support my efforts. I
can not continue to work on major projects like this without sufficient
compensation.
The requested registration fee is $25. That will get you a disk
containing the latest version of SZMODEM and place you on my mailing list for
notification of upcoming releases. Included will be a utility which will
allow you to register your copy of szmodem as well as any copies which you
may receive in the future. Both disk formats (3.5" and 5.25" will be included)
To register, please mail in the included REGISTER.FRM to the following
address along with you check. (Sorry, but I cannot except credit cards)
Scott Baker
6431 Tierra Catalina #48
Tucson, AZ 85718
I may also be reached through my online bulletin board:
The Not-Yet-Named BBS
300,1200, 2400 baud
(602) 577-3650 <Node 1>
(602) 577-3419 <Node 2>
Tucson, AZ
The BBS always has the latest copy of SZModem (and any of my other
projects) available for downloads. We are also part of FidoNet and RBBSNET
and offer several file nad message areas.