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Path: utzoo!utgpu!water!watmath!watdcsu!broehl
From: broehl@watdcsu.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: UUPC: Tips - getting serial ports on some IBM-PC clones to work
Message-ID: <4133@watdcsu.waterloo.edu>
Date: Wed, 18-Nov-87 10:46:28 EST
Article-I.D.: watdcsu.4133
Posted: Wed Nov 18 10:46:28 1987
Date-Received: Sat, 21-Nov-87 02:35:07 EST
References: <1512@van-bc.UUCP>
Reply-To: broehl@watdcsu.waterloo.edu (Bernie Roehl)
Organization: U. of Waterloo, Ontario
Lines: 35
Keywords: UUPC Tips IBM-PC Clones Serial Ports

In article <1512@van-bc.UUCP> skl@van-bc.UUCP (Samuel Lam) writes:

>On some combinations of IBM-PC clones, third-party BIOS, and internal
>Hayes-compatible modems, the low-memory serial port addresses table
>maintained by the BIOS at 47:0 does not get initialized by the BIOS
>correctly during the power-up self-test initialization, and therefore
>pointing to incorrect addresses for the serial ports.
>...
>The fix to this problem is fairly straight forward, all you need to
>do is write a small program (in whatever language you like) to poke
>the appropriate port addresses back into the port table, and invoke
>this program in your AUTOEXEC.BAT file.

You don't even need to write a program.  Just use any text editor to
create a debug script consisting of the following two lines:

e 40:0 f8 03 f8 02 f8 01
q

(this provides for three serial ports; if you only have two, it would
be "e 40:0 f8 03 f8 02", and for only one it would be "e 40:0 f8 03")

Assuming this file is called "comfix.dbg", just put the following line
in your autoexec.bat file:

debug <comfix.dbg >nul

That's all, folks.


-- 
	Bernie Roehl, University of Waterloo Electrical Engineering Dept
	Mail: broehl@watdcsu.waterloo{.edu,.csnet,.cdn}
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