OBM <--> Telebit incompatibility: SUMMARY

Gary S. Trujillo gst at gnosys.svle.ma.us
Mon Feb 4 19:08:36 AEST 1991

In <1991Jan10.095356.17752 at yenta.alb.nm.us> dt at yenta.alb.nm.us
	(David B. Thomas) writes:

> gil at limbic.ssdl.com (Gil Kloepfer Jr.) writes:


> > you're locking the interface speed at 19.2Kb, and you call the Telebit
> > with any 1200 baud modem I've conjured-up to use as a test, it fails
> > miserably.  Could this be due to the modems I'm using?  Could be...

> I think so.  I have my telebit locked at 19.2, and I've managed to connect
> to it just fine (at 1200) with my hayes and my apple...

(Sorry to be so late in responding to this thread.  I'm just now clearing
away over a month's backlog of news.)

When I configured my Telebit T2500 for dialin a number of months ago, I
recalled an earlier discussion about problems with calls from OBMs to
Telebit modems - and had experienced the problem myself, using the OBM,
to call a site with a 'blazer, before I got mine.  I recall that the dis-
cussion last time seemed to strongly implicate the stop-bit shaving that
has been talked about here (I think it's the just the stop-bit that gets
shortened, but I could be wrong).

Anyway, though it took a lot of work and fiddling, I did find a way to
configure my T2500 for dialin that permits it to do *true* autobauding
[no BREAKS, CRs, or other characters need to be sent upon initial login]
(thanks to a replacement getty I got from a fellow UNIX-pc'er, who plans
to release the code after some further cleanup), and have been running
it quite successfully ever since - WITHOUT THE INTERFACE SPEED LOCKED
(since it's only when the interface speed is locked that the bit-shaving
occurs - I think the previous discussion concluded).  Just a few minutes
ago, I did a test for the first time that I probably should have tried
long ago - could I dial in from the OBM (which I hardly ever use any more)
and get a clean connection to the T2500?

The answer is YES - on the first try, with no lost or garbaged characters!

My initial reason for not locking the interface speed was as much to permit
dialin callers to be able to abort output with a kill character as much as
it was to accomodate the sensitivity of the OBM to bit timings, but it's
nice to know that it solves both problems.

Just thought you'd like to know.

    Gary S. Trujillo                            gst at gnosys.svle.ma.us
Somerville, Massachusetts              {wjh12,bu.edu,spdcc,ima,cdp}!gnosys!gst

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