W8SDZ@SIMTEL20.ARPA.UUCP (02/15/87)
The following message is relayed from my RCP/M Royal Oak (MI)
313-759-6569.
--Keith Petersen
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Msg 092 is 23 line(s) on 02/14/87 from BOB CLYNE
to ALL about COURIER VS BYTCOM PROBLEM
The problem I was experiencing with USRobotics Courier modems
dropping back to 1200 bps when calling a BYTCOM modem at 2400 bps
while the BYTCOM stayed at 2400 bps has been solved. Let me repeat
that this problem was only experienced when the Courier was the
"originate" modem calling the BYTCOM at 2400 bps and both modems
reported a successful connection but each modem was at a different
speed. Additionally this problem only occurred with Couriers using
revision 2.43 firmware. Couriers with revision 2.42 worked fine. A USR
technical assistance representative said that the Courier sometimes
mistakes 2400 bps tones for 1200 bps tones and gave me a RMA number
and told me to send the Courier back to USR. My Courier ended up going
back to USRobotics twice. The first time they could not find any
problem so they just returned the modem, letting me think they had
done something to help. After several phone calls to USR, including
some test calls from one of their modems to the BYTCOM they had me
send the Courier back. This time they replaced a crystal and again
returned the Courier. The crystal change helped, the success rate went
from 0% to approximately 25%, still far from acceptab6e. I then
contacted BYTCOM again and they requested that I send the Courier to
them so they could run tests. The result was that BYTCOM was able to
duplicate the problem and made some firmware changes (a new EPROM)
which eliminated the problem. I do not know which manufacturer was
primarily responsible for the problem, although I still suspect that
it was mostly the fault of USR, but BYTCOM was much more cooperative
in trying to locate and eliminate the problem.
Bob Clyne (Royal Oak RCP/M 313-759-6569)