Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!killer!texbell!merch!cpe!hal6000!trsvax!uhclem
From: uhclem@trsvax.UUCP
Newsgroups: comp.sys.tandy
Subject: Re: Tandy RS-232 port problems.
Message-ID: <193300106@trsvax>
Date: 3 Mar 89 16:25:00 GMT
References: <5940001@hpfcdc.HP.COM>
Lines: 47
Nf-ID: #R:hpfcdc.HP.COM:5940001:trsvax:193300106:000:2248
Nf-From: trsvax.UUCP!uhclem    Mar  3 10:25:00 1989


<>
R1>The UART on the card is a standard Intel (or other) 8250, nothing exotic
R1>about it, and there's a pretty good description of how to program it in
R1>the manual.  If you lost the manual, you can probably locate an Intel
R1>peripheral manual quite easily.

Sorry, but Tandy does not use plain-old 8250's.  They use 8250A's, which
have 10 significant problems fixed over the 8250" ".  However, there was a
lot of software written for "real" IBM PC/XTs that expect the presence of the
bugs and won't work reliably if the bugs are fixed.  At the same time,
the BIOS drivers provided with the 1000 series expect the 8250A, so
just replacing it with the 8250" " will break the BIOS.

To make matters worse, some second-source vendors do not use the "blank",
A or B designation on the 8250, since they never produced a "blank" part.
So the part number alone may be insufficient to determine if this is
the problem.

A few years ago National Semi was real paranoid about Tandy ordering several
zillion 8250A's when everyone else in the clone industry was buying 8250" "'s,
and they went to great lengths to make sure that Tandy would not return the
chips and want 8250" "'s when the differences were discovered.

FYI, the 8250A and the 16450 are equivalent (have the same bugs fixed)
as are the 8250 and the 8250B.

Since you have an HX/EX, you are probably using a "real" Tandy serial
adapter.  If you have a third-party RS-232 board, make sure they used an
8250A or this may be your problem.

Otherwise, I would say you have a terminal emulator that was coded to
expect the 8250" " and not the 8250A.  I have found this to be the case
on many of these "free-ware" and "share-ware" terminal emulation programs.
Most professional packages expect both since it could be run on an XT OR
an AT-class system that has only had 16450's, which do not have the bugs.


<This information is provided by an individual and is not nor should be
 construed  as  being  provided  by  Radio  Shack or Tandy Corp.  Radio
 Shack/Tandy Corp has no obligation to support the information provided
 in  any way.   So there.>
						
					"Thank you, Uh Clem."
					Frank Durda IV @ <trsvax!uhclem>
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