Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!csd4.milw.wisc.edu!leah!itsgw!steinmetz!uunet!visdc!jiii
From: jiii@visdc.UUCP (John E Van Deusen III)
Newsgroups: comp.unix.microport
Subject: Re: TrailBlazer with V/AT
Summary: For 19,200 baud set S51=254
Keywords: Need Setup Pointers
Message-ID: <252@visdc.UUCP>
Date: 31 Dec 88 00:11:26 GMT
References: <354@cocktrice.UUCP> <1791@wa4mei.UUCP>
Organization: VI Software Development Co., Boise, Idaho
Lines: 18

From your list of register contents, the setting S51=255 (automatic
speed select) defaults to 9,600 baud.  There is a poorly-documented
setting of S51=254 that defaults to 19,200 baud.  The TB+ really
needs to be fed at 19,200 because the theoretical data rate is higher
than 9,600 baud.  The higher rate gives the processor more time to
do compression and error correction too.

A 9,600 baud interface speed at the receiving end is less critical
because the processing has already been done.  Some systems don't like
unsolicited input at 19,200.  A backbone site like uunet, that transmits
at 19,200 baud (S51=254), can very effectively send news to a site
running a TB+ at 9,600 (S51=255).

Since you have an I/O board with an effective flow control protocol,
I can't see why you wouldn't want to simplify your life and set
S51=5, 19,200 baud interface speed at all transmission modes.  You
can feed the TB+ at 19,200 and the modem with take care of the rest,
even talking to a Bell 103 with no modem control.