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1989-12-23
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220 lines
------------------------------------------------------------------------------
C C H L L - M O D E M
C-MODEM
------------------------------------------------------------------------------
Hanns Ludwig Lippmann Cultural Center (CCHLL) 1989
Lavio Pareschi - all rights reserved
As a shareware program, this is not to be to sold or held. DISTRIBUTE IT !
------------------------------------------------------------------------------
C-MODEM
This is a protocol driver that works similarly and better than DSZ (TM by
Owen Technology). It just includes a whole new file transfer protocol, built
around the idea of crash recovery, easy of use and great performance.
This new protocol, C-MODEM, provides reliable file transmission even in the
worst conditions, as it adapts itself immediately to any errors that may
occur ( even in the so called 'error free' modems ).
SOME CHARACTERISTICS
""""""""""""""""""""
>> MAJOR Features of this new communications protocol
(release 1.00)
1 - Transmission CRASH Recovery
Being interrupted by any condition, the file transmitted is saved with the
extension file.BAD til the last byte received correctly.
In the next connection/transmission, the same will be completed automatically.
2 - MUTABLE DATA : crc blocks on data blocks of variable size
Depending on velocity and errors during transmission, as well as line
conditions, the size of data-blocks between crc-blocks will freely vary from
32 to 4096 bytes.
This reduces the amount of control bytes added to the transmission and
minimizes data repetition.
The result is an excelent true transfer rate.
3 - FULL duplex
The transmiter doesn't stop every block to receive useless answers.
The transmiter occurs without pauses between blocks.
The receptor only warns when something wrong happens.
4 - EXACT size
The file will have the exact size in bytes as the original one as it is
up/dowloaded, without useless added bytes to complete blocks of fixed size.
------------------------------------------------------------------------------
FILES IN THIS PACKAGE
Self-extract CMODEM11.COM (by LHarc):
CMODEM.EXE
Executable File to be used as an external protocol (dos).
CMODEM.DOC
This doc file
RXPCPL.BAT
Bat file for ProcomPlus (download).
TXPCPL.BAT
Bat file for ProcomPlus (upload).
RX.BAT & TX.BAT
Bat files for use via Dos, with any communications package that
allows DOS access during connectionn and use of interrupt COM vectors.
RXBBS.BAT & TXBBS.BAT
Bat files examples for use in BBSs.
SHARE.TXT
Shareware concepts.
COMMANDS:
"""""""""
CMODEM [/port=i][/rx][/tx][/baud=n][/off][/bbs] [filename]
/port = 1 (com1), 2 (com2), 3 or 4. Default = 1, to be used.
/rx for downloads, default.
- obs: it's not necessary to type the filename during downloads,
the transmiter will do the job.
/tx for uploads.
- obs: filename needed
/baud = 300, 1200, 2400, 4800 or 9600 or 0
- to initialize serial port with baud, parity, stop and word.
- if not specified, it will be automaticaly detected and used the same
existing configuration of the serial port.
- if baud=0 then no baud detection will be made, being unknown, and it will
use the remaining existing configuration of serial port;
Obs: the goal of "baud=0" is to disrupt the auto baud detection, if this
is not correct, as it relies on hardware;
- it maybe possible to achieve better efficiency if this paramater is used
to pinpoint the correct baud rate in any case;
/off to turn off the CRASH recovery function (so it will OVERWRITE any file
that was not completely transmitted)
/bbs to use C-Modem in special cases
- no change in ctrl-break and ctrl-C interrupt vectors.
- no pause and alarm at return
filename = name of file to be transmitted
- allways necessary when specifying /tx (upload).
- if present on /rx then has priority.
IMPORTANT:
Some com softs, as ProcomPlus, let the serial port as is on going to Dos.
Others, reset or modify de serial chip and maybe necessary to reinitialize it
with /baud=xxx.
COM PORTS:
Com1 : 3F8 - 3FF - IRQ4
Com2 : 2F8 - 2FF - IRQ3
Com3 : 3E8 - 3EF - IRQ4 (not standard)
Com4 : 2E8 - 2EF - IRQ3 (not standard)
-------------------------------------------------------------------------------
GUIDELINES:
""""""""""
>>>PROCOMPLUS<<<
TXPCPL.BAT:
cxmodem /tx/porta=1 %1
- in setting up Procomm Plus (Tm DataStorm Thecnologies Inc.) you may use
txpcpl.bat as an external protocol.
- starting an upload, ProcomPlus will ask you a filename to transmit,
filename that will be recognized by the parameter %1 used in the .bat file.
- no filename is needed during the download
- you may edit those .bat files to configure it correctly with your system.
GTPOWER , QMODEM, ZCOMM, MIRROR and others.
- access the DOS shell
- give the .bat command:
> RX (to download) or
> TX filename (to upload)
this, only, will execute the external protocol.
Hint:
Read about /baud before try this product.
BBSs
- returns error level 0 if transmission ends ok
- returns error level 1 if transmission ends bad
RECOVERY
Aborted transmissions give the file x the name x.BAD <-- IMPORTANT
So, no confusing is done.
If you want to recovery a file aborted with other protocol, rename to file.BAD
and try C-Modem!
DISTRIBUTION OF THIS PRODUCT
""""""""""""""""""""""""""""
You and your friends are welcome to share and evaluate this package. This
documentation must go with all copies of this shareware. To avoid problems,
it's highly recommended that C-MODEM is ONLY distributed in this package
with the same files, checking the same CRC values, shown here. It can be
packed in any kind of compressor as long as the package integrity is not
damaged. If any annomaly in the package should be noticed, is to be notified
to the board's operator ( on which you got it ). Wipefile any file before
it behave weirdly.
REGISTRATION
""""""""""""
After a evaluation period, ethical users M U S T register their copy of this
package. They can make sending a U$20 bill to:
****** ******
Centro Cultural Hanns Ludwig Lippmann (CCHLL)
RIO DE JANEIRO ( RJ )
Caixa Postal 34.045 CEP 22.472 BRAZIL
****** ******
>>> Registration of this product bypasses the shareware announcement and
gives the registered user other advanced functions and the right to
receive future versions. Just pay once !!!
-------------------------------------------------------------------------------
Any major problem, contact the CCHLL-BBS/RJ - BRAZIL.
Door #1: 55-(021)285-6228 (2400C, 1200C, 1200B, 300Bell).
Door #2: 55-(021)265-7380 (1275C, 300B, 300Ccitt).
Configuration: 8-N-1
---------------------------- < end of document > -----------------------------