Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!umich!sharkey!cfctech!teemc!ka3ovk!irscscm!mfaurot
From: mfaurot@irscscm.UUCP (Michael Faurot)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Motherboard Size
Message-ID: <1991Jan17.054057.13243@irscscm.UUCP>
Date: 17 Jan 91 05:40:57 GMT
References: <2415@bnlux0.bnl.gov> <1991Jan15.191014.10@d.cs.okstate.edu>
Reply-To: mfaurot@irscscm.UUCP (Michael Faurot)
Organization: Internal Revenue Service, Washington, DC
Lines: 46

In article <1991Jan15.191014.10@d.cs.okstate.edu> ong@d.cs.okstate.edu (ONG ENG TENG) writes:
>From article <2415@bnlux0.bnl.gov>, by weiner@bnlls1.nsls.bnl.gov (Gary Weiner):

>So, to upgrade you should probably get a baby-AT motherboard.  Remember, you
>might also want to change your hard drive controller from 8-bit to 16-bit.
>Anyone who know better regarding the form factors please correct me.

I've recently performed a similar operation.  I've merged parts from an XT
with an original IBM AT mother board.  I wound up going with a whole
new full size AT case.  I'm not concerned about desktop real estate
because I just turned the thing on it side and set it next to my desk.

Some other concerns that should be kept in mind when performing a
merging of this type are the following:

1)	You may need a new keyboard.  Most newer keyboards are switch
	selectable for the type of system they connect to (XT or AT
	class).  I'm not 100% certain, but I believe there is a
	difference between the scan codes generated by an XT vs an
	AT keyboard.  If you can adjust your keyboard you're probably
	all right.

2)	You should look at your power requirements.  Most ATs have
	at least 200W power supplies.  I believe most of the
	XT power supplies are typically 150W.  Also keep in mind that
	an XT power supply will probably not fit into an AT style
	case.  (I learned this one the hard way).  XT and AT power
	supplies have different physical dimensions and mounting
	characteristics.

3)	You will probably be able to get away with using your XT
	hard disk controller in an AT class machine by simply
	claiming in the CMOS set-up that no hard-drive exists
	on the system and letting the on-board ROMs on the XT
	controller handle the rest.  In my conversion/merging process
	this did in fact work, but for some reason the XT floppy controller
	would not work, and the machine would not recognize the
	floppy drives.  I could boot from the hard drive, but
	could not access the floppies at all.  I solved this
	by just purchasing a new AT class hard/floppy controller.

4)	If indeed you are moving from an XT case to an AT case, don't
	forget to get rails for your drives if the case doesn't
	come with them.

--Mike Faurot (mfaurot@bogart.UUCP)