Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!ames!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.sys.apple2
Subject: Re: Modem/Serial ports to 38.4k baud or >
Message-ID: <13278@smoke.BRL.MIL>
Date: 3 Jul 90 03:20:28 GMT
References: <3374@crash.cts.com>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 20

In article <3374@crash.cts.com> bobl@pro-graphics.cts.com (System Administrator) writes:
>Is there a CDA or something out there that will allow the GS modem port to go
>beyond the 19.2k baud speed?

The baud rate is a function of the 8530 SCC chip, which of course you're stuck
with, the 3.6864 MHz crystal oscillator attached to it, which cannot be changed
without breaking the use of the serial ports by other software, and the set of
parameters that you load the 8530 with to specify how to divide down the
oscillator to obtain the bit rate.  Using a divisor of 1, you can attain up to
614.4 Kbps.  However, the built-in port firmware does not provide access to
this, so you must roll your own software.  I have a C header for the GS 8530
that makes programming this critter easier, if you need it.

>I'm beginning to feel that I'm working on a computer that has fallen behind
>the times here..I hope someone can help before I have to pack this GS in and
>go with something that can support the current technology...

19.2Kbps is hardly "current technology".  Incidentally, the effective transfer
rate will probably be less than the link-level bps used, due to overhead in
the software driving the port.