Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hpsgpa!plim
From: plim@hpsgpa.HP.COM (Peter Lim)
Newsgroups: comp.sys.ibm.pc
Subject: Re: XT --> 386SX
Message-ID: <340039@hpsgpa.HP.COM>
Date: 29 Nov 89 01:58:46 GMT
References: <9361@batcomputer.tn.cornell.edu>
Organization: HP Singapore IC Design Ctr
Lines: 21

> I have an old XT clone and I'm tempted by some of the cheap 386SX
> motherboards.  It would be nice to be able to salvage some of the old
> stuff, particularly the drives (ST225's).  Most of these boards have a
> couple of 8 bit slots, but I assume you can't just plug in an XT drive
> controller (for bus timing and port assignment reasons).  Is there a way
> to do this? If anyone out there has tried such an upgrade and has any
>
I don't see why not, unless your drive controller is a real old vintage;
i.e. made in the good old days before the arrival of AT and/or Turbo XT.
In that case you might not be able to run the controller at a bus speed
of 8 MHz which is pretty much a standard now. Of course most latest board
should have the option to let you run the bus at 12MHz or higher, but
you'll need newer controller cards to live with that. In general, if
you plug your controller card into an 8MHz 0Wait AT and it works, you
should have no problem. Of course you must make sure that the 386SX
you intend to buy can run the bus at 8MHz (not the CPU speed); preferrably
selectable. I have a 25MHz 386 which can change the bus speed from 8MHz
to 12.5MHz (half CPU clock), I am know using a PERSTOR controller card
on loan and the stupid thing can't hack 12.5MHz, so I am forced to run
the bus at 8MHz, but it still work  :-).. ...... wait till my ESDI
drive comes and I'll be able to run at 12.5MHz again !