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From: aryeh@eddie.MIT.EDU (Aryeh M. Weiss)
Newsgroups: comp.unix.xenix
Subject: Re: Need help w/Apparat Ram Card with Microport 2.2
Message-ID: <6120@eddie.MIT.EDU>
Date: Thu, 18-Jun-87 19:05:48 EDT
Article-I.D.: eddie.6120
Posted: Thu Jun 18 19:05:48 1987
Date-Received: Sun, 21-Jun-87 15:35:18 EDT
References: <114@qetzal.UUCP>
Reply-To: aryeh@eddie.MIT.EDU (Aryeh M. Weiss)
Organization: MIT, EE/CS Computer Facilities, Cambridge, MA
Lines: 40
Keywords: double fault panic 256k dram 64k dram

In article <114@qetzal.UUCP> rcw@qetzal.UUCP (sysop) writes:
>Software: Version 2.2L of Microport System V/AT. "Big" kernel.
>	  (Problem also occurrs with small kernel)
>
>Problem: Rom checks memory 640k base, 1536 extended. I do a 
>         telinit 2 to go multi-user. I then vi the Makefile
>         for news 2.11. Kernel tells me either: NMI in system
>         mode, or NMI in user mode, then displays the Makefile.
>         I then do 'j's down the page. I do 'k's back up the
>         page. Disk light flashes, then "DOUBLE FAULT" ocurrs,
>         a bunch of hex info is displayed, and the message 
>         appears: "panic - general protection" is displayed.

I had this type of probelm using a Wells American A*Star II and a 
PC-Limited 1.5 MEG card. At 8-0, or 8-1 the system had obscure
and non-reproducible errors when doing a big compile. NMI errors 
occured, but memory passed advanced diagnostics. I did not have as
much trouble at 6-0 or 6-1. 

I recently installed a Micron 4 MEG memory card (100ns chips) and
found that I had to tell it to force a wait state, or else I got the
same obscure (and non-reproducible) errors. Micron writes in their
manual that some AT clones have different timing than an IBM AT, and they
will not work properly at 8-0. Apparently, setting the Wells to insert
a wait state does not do the trick. Something about the timing...

Also, users of Microport UNIX will be glad to know that the 80287
floating point crash (system hangs when there is a floating point
error) has been fixed, and the patch has been sent to uport for inclusion
in their next release. Also, the clock problem has been fixed.

As I am inexperienced at posting news (this is my first time) send
mail to me to get patches. If I get a flood of replies, I will post
the fixes, but you will need the source to build a new lib1 to link
to the kernal.


-- 
aryeh@eddie.mit.edu
mit-eddie!lees-rif!aryeh