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From: ford@crash.cts.com (Michael Ditto)
Newsgroups: comp.sys.att
Subject: Re: 3B1 HW
Message-ID: <2092@crash.cts.com>
Date: Sat, 5-Dec-87 16:14:57 EST
Article-I.D.: crash.2092
Posted: Sat Dec  5 16:14:57 1987
Date-Received: Thu, 10-Dec-87 22:55:16 EST
References: <31200010@ccvaxa>
Reply-To: ford%kenobi@crash.CTS.COM (Michael Ditto)
Organization: Crash TS, El Cajon, CA
Lines: 58
Keywords: hardware, Unix PC, documentation
Summary: Here's where to get the hardware reference manual

In article <31200010@ccvaxa> aglew@ccvaxa.UUCP writes:
>I'd like to play with my 3B1's hardware a bit, and have several questions:
>
>(1) What are the best manuals to get? I was recommended the Technical
>    Reference, but but have not yett obtained it in two months' waiting.

I heard that the "Service Manual" was quite useless, and that the "Hardware
Reference Manual" was the one to get.  Rather than pay the hundreds of
dollars that AT&T wants, I bought the Convergent S/50 version from a
Convergent dealer for $75.  Here's where I got it:

	Integrated Systems Group
	920 East Broadway
	Glendale, CA  91205
	(818) 502-1414

	(order the "Convergent S/50 Hardware Reference Manual")

The front cover says "Convergent S/50", but in the manual itself, only
the name "AT&T Unix PC" is used.

The manual contains three sets of schematics and some information about
diagnostics and troubleshooting and theory of operation.  It does not
give a good desctiption of the expantion slots.

The three sets of schematics are for the three different motherboard
memory configurations.  The 512K and 1Meg versions are correct, but the
2Meg schematic is missing a few pages.  I was able to use the information
to upgrade a 1Meg 7300 to 2Meg, though.  If anybody wants a description
of this procedure, let me know... I'll post if there's interest.

>(2) Has anybody interfaced SCSI to the UNIX PC?

I heard a rumor that someone was planning to release a SCSI card, but
haven't heard of any real products.

>(3) Has anybody interfaced a larger monitor?

If you mean a physically larger CRT, then yes, a few people on the net
claimed to have done it.

>(4) Does anyone know how hard it would be to break past the 4M limit
>    on a process' virtual address space? Ie. use more address lines 
>    at the MMU?

This would be VERY difficult.  It would require designing a replacement
for the address translation custom IC, along with adding more page-table
RAMs.  It would require running more address bus lines to various places
on the motherboard.  Probably the most difficult part would be changing
the system software.  I would classify the job of patching the kernel
to do this in the "impossible" category.  Of course, if you think you
can get source...

-- 

Mike Ditto					-=] Ford [=-
P.O. Box 1721					ford%kenobi@crash.CTS.COM
Bonita, CA 92002				ford@crash.CTS.COM