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From: bobm%pixel@uunet.UU.NET
Newsgroups: comp.sys.nsc.32k
Subject: Re: I can't boot minix.
Message-ID: <9101020428.AA09445@pixel.convex.com>
Date: 2 Jan 91 04:28:29 GMT
Sender: news@daver.bungi.com
Lines: 37
Approved: news@daver.bungi.com

Well, it was indeed a hardware problem.  I managed to produce an
anomaly using the ROM monitor's "fill", "dump" and "crc" commands,
and quickly narrowed it down to "sometimes writes to address N modify
address N xor 0x100000."  It turned out that signal A20 wasn't making
it to the page comparator, U36.  Now that's fixed, and Minix comes up
partway.  When I boot, I get this.

	NS32000 ROM Debugger
	Version: Sat Jul 14 19:25:31 PDT 1990
	RAM free above 0x1554

	Command (? for help): read 0 2000 80
	Command (? for help): run 2000
	Minix 1.3 kernel version: Sat Sep 29 14:08:32 1990
	Pages of user memory: 973
	    Start user pages: 0x33000
	Tue Nov 30 00:00:01 1999   (hmmm.. better reinstall the no-slot clock)
	*****************************************************************
	*								*
	*	 W E L C O M E   T O   M I N I X   3 2 0 0 0		*
	*								*
	*	       (c) Copyright 1987 Prentice-Hall			*
	*								*
	*****************************************************************
	/dev/hd3 mounted
	login: 

But it doesn't listen to anything I type.  Would anyone care to
confirm or deny that this is the first time the machine has tried to
do interrupt-driven input from the console?  I'm guessing that the ICU
works, because I booted the hard drive, and that requires SCSI
interrupts.  Either DUART 0 is scrozzled or there's a bad connection
on signal /DUAR0 (*).

Thanks to the several people who sent suggestions.

					K<bob>