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From: cbenda@unccvax.UUCP (carl m benda)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 386 in IBM AT?
Message-ID: <786@unccvax.UUCP>
Date: Mon, 3-Aug-87 21:38:17 EDT
Article-I.D.: unccvax.786
Posted: Mon Aug  3 21:38:17 1987
Date-Received: Thu, 6-Aug-87 00:50:01 EDT
References: <1272@killer.UUCP>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 28
Keywords: 386, 20mMHz
Summary: no no no

In article <1272@killer.UUCP>, robertl@killer.UUCP (Robert Lord) writes:
> Intel is coming out with a 20Mhz (whew!) 80386 chip later this year, and
> I would like to drop it into me AT to make it into a fast desktop.  If I
> did this, would I have any problems with existing software/hardware?
> Would I be able to use software designed for the 386?  Would all the


No No and Finally No.  The problem with what you described is the fact that
your AT was probably designed to run at NO more than 10MHz.  This is because
the memory is probably no faster than 120ns RAM.  What this means is that if
you replace  your 80286 with a 80386 inserted into a Chetah Adapter, it will
perform at a MIPS rate which is no better than your current configuration.

What you will gain is the addressing capabilaty of the 80386, namely, 4G
bytes, and 1Meg segments, instead of 80286 which is 16Meg and 64K segments.
With this in mind, a 20Mhz 80386 chip would be wasted in your machine.

What you would really like to do is keep everything in your AT but your
mother board.  Replace the mother board with an 80386 motherboard which
will allow you to have a 20Mhz machine with 32 bit word memory moves, your
AT can only do 16bit memory moves.  Here again memory for this machine will
be exspensive, I believe with a 20Mhz clock rate the memory needs to be
at least as fast as 70ns.  This is a guess since my ALR 386 uses 80ns ram 
and has a 16Mhz clock rate.

hope this helps
/Carl
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