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1982-11-01
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271 lines
CP/M MODEM PROGRAM DOCUMENTATION
by Mark M. Zeiger and James K. Mills
11/04/80
( updated for "portable" version by BRK )
This program uses the file transfer routines written by Ward
Christensen in his CP/M file transfer program (V2.0 as of 8/6/79)
and is compatable with his program in single file transfer mode.
Multi-file transfers are only possible between two systems running
the program described below.
This program has two functions:
1. Communication
2. Program transfer
COMMUNICATIONS
The program may emulate a terminal or echo data back to sender (act
as a computer).
Terminal Mode - 'T' Option
The terminal mode may be called with or without a file name.
If a file is specified (it should be a new file), then
anything received by the modem may be saved in memory and
later written on disk. The save feature is toggled ON/OFF by
Control-Y. A colon (:) will be printed at the beginning of
each line when memory save is active. The colon will not be
transmitted over the modem nor will it be saved in memory.
If a file is not specified, then memory save can not be
activated.
If the memory buffer is full (the buffer is from the top of
the program to the top of the segment ), the contents are
automatically written to disk (but the file is not yet
closed). Communications may then continue with the buffer
reinitialized. The computer with which you are communicating
must accept the X-ON and X-OFF (Control-Q and Control-S)
conventions or data will be lost.
When communications are over, use Control-E to exit from the
Terminal mode and enter the Menu. The file to which you are
writing must then be closed by using the 'WRT' command. If
this is not done, all data will be lost. I decided not to
close the file automatically since there will be times when
you leave terminal mode and then decide to re-enter. This may
be done while in the Menu by using the 'RET' command. You may
re-enter Terminal mode and save in the same file as many times
as you wish as long as you have not closed the file with the
'WRT' command.
While in Terminal mode, Control-T will put you in File
Transfer mode. This will allow you to send the contents of an
ASCII file over the modem. This routine does no error checking
and there are no protocols specified between this program and
the receiving computer other than that it should be ready to
receive data via the modem. Control-X will cancel the
transfer.
Computer mode - 'E' Option
This mode echos data received by other computer. Only one
computer may be in this mode at one time. There is no save
feature in this mode. Useful if you wish to communicate with
somebody running the terminal portion of the program.
File transfer - 'S' and 'R' Options
These features are the same as in the CP/M Modem program
written by Ward Christensen except that upon completion of the
transfer, control returns to the Menu unless the secondary 'T'
option has been selected. In the latter case, control returns
to Terminal mode. Remember that if you are operating a remote
computer using a timesharing program (such as Ward
Christensen's "BYE"), the remote should be instructed to send
or receive in the quiet (Q) mode as a secondary option.
Examples of commands for sending and receiving are listed
below. You may also have to use the quiet mode when using
direct computer to computer communication at speeds higher
about 2400 baud because the console listing speed is too slow.
The transmission protocol involves sending data in packets of
about 128 bytes along with an 8 bit checksum. The receiving
system recomputes the checksum and compares it to one received.
If the checksums agree it sends back an acknowledgement character
and the sending system sends the next packet. If the checksums
do not match, a negative acknowledge is sent and the sending
system automatically sends the packet again ( it will retry
at most 10 times before giving up ).
Multi-file transfers
Using the B (batch) secondary option, more than one file and
ambiguous filenames may be transferred. To send files, use the
primary option "S" and the secondary option "B" (along with
any other secondary options and baudrate). To receive the
files being sent, use the "R" primary option and the "B"
secondary option. Files may not be named since filenames are
sent by the sending program, but a disk drive may be specified
(or else the files are written to the default drive).
Backup option
There is a byte at the beginning of the program (106H) that
will create a backup file if a file on the disk has the same
name as the file being received in multi-file transfer (see
MODEM.SET). If this byte is set to 0FFH, a backup file will be
created. If it is zero the file on the disk will be deleted
before the new file is received. If you are running CP/M 2 and
a file on the disk is designated R/O or SYS, a backup will be
created whether the byte at 106H is set or not.
Be careful - if you are running CP/M 1 and the drive on which
you are receiving has an R/O file with the same name created
by CP/M 2, the R/O file can not be accessed (found, changed,
erased, etc.) by CP/M 1. You will therefore have two files
with the same name when you are running CP/M 2. To fix this
problem, use CP/M 1 to change the name of the file that is not
R/O. Then use CP/M 2 to do what you want with the R/O file.
Examples: ( note in the examples that follow, Ignore the
secondary O or A commands as the portable
version cannot set Originate or Answer mode- it
must be done manually on the modem)
The sender enters SBOT.600 B:*.COM to send all the COM
files on disk B. Also specified were originate mode 600 baud
(PMMI modem) and return to terminal mode when done.
The receiver enters RBA.600 to receive all the files
being sent on the default drive.
The sender enters the command SB.600 ASM.COM *.HEX B:M*.*
which will send ASM.COM from the default drive, all the HEX
files from the default drive, and all the files starting with
"M" from the B drive.
Multifile transfers may only be done from the menu. It may not
be specified when the MODEM program is called. In other words
A>MODEM SAB *.COM will result in an INVALID OPTION error
message.
Return to Menu - 'M' option
When asked to select an option, 'M' returns to Menu.
The MENU
If the Modem program is entered with no option, the Menu is
called. The Menu gives the choice of selecting the standard
options as defined by Ward Christensen (T, E, R, and S). The
Terminal mode has been greatly expanded as described above.
The "R" and "S" commands must be called with a filename or you
will be required to enter the primary command (S or R) and the
filename again (but NOT the secondary options). If you want
multi-file transfers, then the "R" option does not need a
filename.
RET - You may also enter terminal mode using the 'RET' command, but
no data will be saved since a file may not be named with
'RET'. Use the 'RET' command to RE-ENTER Terminal mode after
it has first been entered with the 'T' option. If this is
done, you will still be able to save the communications if you
were doing so before you exitted the terminal mode.
WRT - The 'WRT' command must be used after leaving Terminal mode.
This writes the last buffer to disk and closes the file.
Failure to use the 'WRT' command results in loss of all data
and a file of length zero.
DEL - The 'DEL' command erases the most recent file accessed in
Terminal mode. Useful if you decide after communications that
you don't want to save information just gathered.
DOS - The 'DOS' command reboots and returns to DOS.
XPR - The 'XPR' command is a toggle which causes the menu to be
printed or not printed. Initially the menu is on unless the
program is called with the "X" option (ie. A>MODEM X ).
DIR - The 'DIR' command lists the directory of a DOS disk. A drive
may be specified (ie. DIR B:) or the default drive will be
listed. After the directory is listed, the menu will not be
printed whether XPR mode is on or off. If XPR mode is on and
you wish to see the menu, hit return.
^B - Control-B while in Terminal (or Echo) mode allows change of
baudrate "on-the-fly." A carriage return gives 300 baud; all
other rates (110-600) must be explicitely stated.
LISTING OF COMMANDS AND OPTIONS
Primary options
S - send a CP/M file (must specify file/s)
R - receive a CP/M file (must name file unless B sec opt used)
T - terminal mode (specify file if memory save wanted)
E - terminal mode with echo
M - return to menu
X - used only when program is called to initially
toggle menu off
Secondary options
B - multi-file mode for sending and receiving files
T - return to terminal mode after transfer (memory save off)
R - view what is received in file transfer
S - view what is being sent in file transfer
V - view what is being sent or received in file transfer
T - Terminal mode (used with remotely controlled computer)
O - originate mode -- NOT IMPLEMENTED IN PORTABLE VERSION --
A - answer mode "" ""
.xxx - baud rate xxx (xxx = 110-9600 for the serial port )
EXAMPLES (fn = filename, ft = filetype)
Send file, originate mode, 300 baud
SO fn.ft
Send another file, same mode and baudrate
S fn.ft
Receive file on B drive, 600 baud, ans mode, view what is
being received, return to terminal mode
RART.600 B:fn.ft
Send all COM files, no messages on console, same baud and mode
as last transfer
SBQ *.COM
Send two files from two different drives
SB A:fn1.ft1 B:fn2.ft2
Receive files being sent by above on drive A (baudrate must be
same and modes opposite)
RB A:
Terminal mode, save communication in file, 300 baud (default
rate), originate mode (in terminal must type CTRL-Y to start
save, in menu must type "WRT" to close file)
TO fn.ft
Any problems or bugs, please call me:
Or latest revisor:
Mark M. Zeiger James K. Mills Bruce R. Kendall
198-01B 67th Ave. 824 Jordan Place Mt. View, Ca.
Flushing, N.Y. 11365 Rockford, IL 61108
(212) 454-6985 (815) 398-0579 415-967-3613