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From: sward@cfa.HARVARD.EDU (Steve Ward, CF)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: AT Bus specs
Message-ID: <402@cfa.HARVARD.EDU>
Date: 23 Jul 90 21:45:11 GMT
References: <58084@bbn.BBN.COM>
Sender: news@cfa.HARVARD.EDU
Lines: 56

From article <58084@bbn.BBN.COM>, by clements@bbn.com (Bob Clements):
> A while ago (and every few months, I guess) the question came up
> of what are the timing specs for the PC/AT bus.  The answer, as
> always, was that there is no published spec for the timing, ...

Here it is:

Book:
-----
AT BUS DESIGN (IEEE P996 Compatible), by Edward Solari (member, P996
Committee) published by Annabooks, 1990, ISBN 0-929392-08-6
Annabooks tel. 800-462-1042, 619-271-9526
Annabooks, 12145 Alta Carmel Court, Suite 250, San Diego, CA 92128

This bus gives all timing and electrical info.  The book is quite good.
However, the orientation of the books is the implementation of the bus
on a traditional CPU platform motherboard.  This is okay, except that
no real attention is given to the other environment, the so-called
passive backplane system, though all needed technical information is
in the book for extrapolation to this environment, the exercise left
to the reader, by default.  The book is also very overpriced at $60.00,
but if you need the info right now...

I have heard rumors about other books of similar ilk coming out, but
for me these remain uncomfirmed apocryphal rumors.

Note that REAL SOON NOW, the IEEE will publish the P996 specification:

Personal Computer Bus Standard P996, IEEE (last I heard, this was
at draft 2.00 and essentially done with respect to the technical
details, leaving only some cleanup and administrative work to be
completed, but this may or may not be a true characterization.  Contact
the IEEE for draft standard copies, if this is even possible).

Also available, more or less:

ISA BUS Specifications and Applications Notes, Janauary 30, 1990,
Copyright 1989, Intel Corp.  --contact Intel for a copy of this Intel
document; they will probably give/sell you a copy.

Note that this book deals with the ISA bus and some extensions to it,
but gives a very light treatment to the EISA bus (32-bit bus).  The
ISA bus, with some extensions, is essentially the PC-AT bus, of which
the PC-XT bus is a subset, so this book deals thoroughly with the
standard (now it is, I guess) PC-XT/AT 8-bit and 16-bit busses, known
collectively as the ISA bus.

I do not know if the IEEE spec. goes beyond this, to cover the 32-bit
EISA bus, of which ISA is a proper subset.  For those who really want
the EISA info, contact COMPAQ, as they have published a technical guide:
Technical Reference Guide, Extended Industry Standard Architecture
Expansion Bus, Copyright Compaq Computer Corp, 1989.

-- Steven M. Ward   ward@cfa.harvard.edu

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