[comp.sys.ibm.pc.misc] Motherboard Size

weiner@bnlls1.nsls.bnl.gov (Gary Weiner) (01/15/91)

 	I have a No-Name IBM-PC Clone (8088) that I purchased ~2 years
ago. I am now thinking about upgrading to a 286 Motherboard(on my way to
a 386). The only problem is that I don't know what size case (AT, XT, Baby)
I have. How would I detrmine this? Are their standard measurements/dimensions
etc. ? Your help is appriciated.

Gary J. Weiner  | Brookhaven National Laboratories  | "I'm not a bigot,
PO BOX 715      | National Synchrotron Light Source | I hate everybody!"
Upton,NY 11973  |    weiner@bnlls1.nsls.bnl.gov     |

ong@d.cs.okstate.edu (ONG ENG TENG) (01/16/91)

From article <2415@bnlux0.bnl.gov>, by weiner@bnlls1.nsls.bnl.gov (Gary Weiner):
> 
>  	I have a No-Name IBM-PC Clone (8088) that I purchased ~2 years
> ago. I am now thinking about upgrading to a 286 Motherboard(on my way to
> a 386). The only problem is that I don't know what size case (AT, XT, Baby)
> I have. How would I detrmine this? Are their standard measurements/dimensions
> etc. ? Your help is appriciated.

Well, I think there is only 3 types of non-customized boards ever 
on the market: 1) the 5-slot original PC
               2) the 8-slot XT, currently also the baby-AT or mini-AT
               3) full-size AT
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.

knut@tts.lth.se (Ake Knutsson) (01/16/91)

In article <2415@bnlux0.bnl.gov> weiner@bnlls1.nsls.bnl.gov (Gary Weiner) writes:

> I have a No-Name IBM-PC Clone (8088) that I purchased ~2 years
> ago. I am now thinking about upgrading to a 286 Motherboard(on my way to
> a 386). The only problem is that I don't know what size case (AT, XT, Baby)
> I have. How would I detrmine this? Are their standard measurements/dimensions

Why don't consider a 386SX motherboard? It's only slightly more
expensive than an 286 board. Then you will get an 386 system and be
able to run 386 software. 

Baby AT size is 8 1/2 * 13 inches. Hopefully that will suit your box.
So it did my PC/XT clone.

In BYTE, April 1990, page 130, there is an informative article on 386
motherboards. 

Regards,
-- Ake

> Gary J. Weiner  | Brookhaven National Laboratories  | "I'm not a bigot,
> PO BOX 715      | National Synchrotron Light Source | I hate everybody!"
> Upton,NY 11973  |    weiner@bnlls1.nsls.bnl.gov     |

_______________________________________________________________________
Ake Knutsson                      	email: knut@tts.lth.se
Dept. of Communication Systems    	       ..!uunet!tts.lth.se!knut
Lund Institute of Technology, SWEDEN	fax:   +46 46 145823

mfaurot@irscscm.UUCP (Michael Faurot) (01/17/91)

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)

ong@d.cs.okstate.edu (ONG ENG TENG) (01/20/91)

From article <1991Jan17.054057.13243@irscscm.UUCP>, by mfaurot@irscscm.UUCP (Michael Faurot):
> 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.

Just to ensure no confusion here, a baby-AT (or mini) motherboard is a TOTALLY
different in size from an original IBM AT motherboard (which is full-sized).
I have used baby-AT motherboard in XT case, and vice verse. 

vandevek@fergvax.unl.edu (James M. VandeVegt) (01/20/91)

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):
>> 
>>  	I have a No-Name IBM-PC Clone (8088) that I purchased ~2 years
>> ago. I am now thinking about upgrading to a 286 Motherboard(on my way to
>> a 386). The only problem is that I don't know what size case (AT, XT, Baby)
>> I have. How would I detrmine this? Are their standard measurements/dimensions
>> etc. ? Your help is appriciated.
>
>Well, I think there is only 3 types of non-customized boards ever 
>on the market: 1) the 5-slot original PC
>               2) the 8-slot XT, currently also the baby-AT or mini-AT
>               3) full-size AT
>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.

Good suggestion, another thing, go to a computer store and look at some
of theirs, ask around and you are bound to find out.  I am not a
hardware expert but if your case is too old, you may stand the chance
of not having the holes line up, which would not be pleasant.

One other thing, don't mess arround with a 286, for just a little more
on today's market you can get a 386SX and if you have the money to
spend, go to a 386-25.  Trust me, computers have very little resale
value; you'll just be wasting your money.

----------------------------------------------------------------------
| James M. VandeVegt             |  University of Nebraska           |
| vandevek@fergvax.unl.edu       |  Computer Science and Engineering |
----------------------------------------------------------------------

----------------------------------------------------------------------
| James M. VandeVegt             |  University of Nebraska           |
| vandevek@fergvax.unl.edu       |  Computer Science and Engineering |
----------------------------------------------------------------------