SPARC rs232 - how to do high speed transfers?

[Alen Shapiro]

I have been trying for the last 3 weeks to diagnose problems connecting
MAC<->SPARCstation1 via RS232 at 19200baud.

POINTS TO NOTE

uucp, ZMODEM and XMODEM do NOT use XON/XOFF and so HW flow control seems
essential. Even on a modem at 2400 baud I have noticed character loss down
RS232 uucp (modem was error correcting MNP).

OBSERVATIONS about hardware control signals

There seems to be no way for the SUN to tell the mac to stop sending (sun
does not generate active HW flow-control signals) When MAC is busy it
drops DTR (at least Microphone II does)

OBSERVED PROBLEMS

Just about any console activity on the SPARC conflicts with incomming
RS232 activity and characters are lost Some SCSI disk activity has the
same effect

CONCLUSIONS

Streaming protocols like ZMODEM are probably not going to be able to
transfer significant quantities of data at high speeds from mac to SPARC
XMODEM may work but a patch is needed to stop Ring-Buffer overflow
messages on the console from causing further character loss (the adb patch
from sun follows; as root 

% adb -w /vmunix - 
splsoftclock+c?x # verify 2680 stored here else DO NOT PROCEED 
.?w 1080 
$q 

then reboot)

QUESTIONS

Has anyone solved this problem, Is there a better NULL-modem cable connect
than a symetrical 2->3 4&5->8 6->20 7->7 between SPARC&Mac.  Who do I
complain to for the lack of RS232 SPARC capability? (0.5 :-))

email me if you like - I'll post a summary.

--alen the Lisa slayer (trying to turn a SPARC into a flame)

...alen%shappy.uucp at crash.cts.com (a mac+ uucp host - what a concept!!)
...alen at crash.cts.com