Aucbvax.1858
fa.info-cpm
utzoo!duke!decvax!ucbvax!fylstra.tsca@SRI-Unix
Tue Jun 23 02:30:47 1981
RS-232 FTP at 9600 baud
This may have been attempted before, but I thought it sufficiently
interesting to report to everyone...
This evening, Term Kovattana and I succeeded in using the MODEM2 program
for reliably transferring files between CP/M systems over an RS-232 link
at 9600 baud. The two systems were an S-100 system (Cromemco Z2-D)
with 8 inch floppy disks and a HeathKit H89 with 5 inch floppy disks.
We used the latest version, [mc]cpm;modem206 asm, modified as appropriate
for the corresponding serial ports. This program transmits binary
files in packets consisting of a header, sequence number, data, and
a checksum, and provides a simple ack/nak/timeout protocol. We used
the "quiet" mode at each end of the connection to avoid problems caused
by program status messages garbaging the transmission. It is a real
pleasure to see a 10K file zipping between systems in seconds!
Incidentally, the initial download from the Z2 to the H89 was accomplished
using standard CP/M tools as follows:
Z2 end H89 end
pip crt:=ftp89.hex pip ftp89.hx=rdr:[b]
pip crt:=con:
ctl-S ctl-Z ; file at this end is flushed
pip crt:=eof: ; file at this end is closed
ren ftp89.hex=ftp89.hx
The [b] switch causes the receiving end to buffer the 10K hex file
in memory until the ctl-S is received as a result of the second command
line at the sending end. Finally, the third command line transmits
a ctl-Z which causes the receiving end to close its file. The '.hx'
file extension is used to prevent the receiving PIP from wasting time
verifying Intel Hex format while reading the file, and is subsequently
renamed to '.hex'.
Next step...attempt to transfer files between a TOPS-20 and a CP/M
system over a hard line at 9600 baud.
Dave Fylstra
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