Questions about old "baby-AT" motherboards

[Ron Bean]

[I don't know if there's a better newsgroup for this, but the PC
hardware groups tend to talk about current hardware, and I need
some information about "antiques"...]

I have an old "lunchbox" style portable with a plasma screen,
currently set up as a 486 with 32Mb of RAM, running Linux. It
works OK, but might work better with more RAM. Two obvious
problems: it uses SIMMs rather than the more common DIMMs, and it
only caches the first 32Mb of memory.

I'm wondering if it might be worth trying to put a somewhat newer
motherboard in it, but there are some constraints:

+It must be "baby-AT" size, not ATX
+It must have at least one ISA slot for the special video card.
+The CPU must lay flat on the board-- if it sticks up on a
separate card, it won't fit because the disk drives mount very
close to the motherboard.
+Obviously, no new motherboard meets these specs, so I'm looking
at used ones.

So the first question is, were there any "baby-AT" motherboards
that used DIMMs, or did that come later?

Second, were there any Pentium-class CPUs (maybe from AMD?) that
don't stick up more than about 1.5" from the motherboard
(including the fan)?

I've looked over the ads on ebay, but they often don't give much
information (and most of them are ATX anyway). Also, many of them
are sold without CPUs, and I need to know which CPUs fit which
"sockets". Does anyone know of a good source for this kind of
information?

 

[Jason D.]

Ron:

There are definitely Baby AT boards that match your requirements. Baby AT
boards of the PII generation were typically socket 7, slot 1, or socket 370.
Slot 1 is out for you because of the height requirement, but socket 370 and
socket 7 will work, provided you use a low profile heatsink/fan assembly.
I'm running one right now that uses 168 PIN DIMM memory, and uses a socket 7
CPU - a Cyrix 266 MHz, specifically. I also used to have a PC Chips board
that would run either a socket 370 or Slot 1 CPU. I ran a Celeron 366
Socket 370 chip in it. Again, it used 168 Pin RAM. If you search on ebay,
try searching for "BABY AT SOCKET 370" or "BABY AT SOCKET 7" as your
keywords, and you could set it to search the descriptions too.

Jason


"Ron Bean" <rbean@execpc.com> wrote in message
news:f330cab5.0402202001.7510215a@posting.google.com...

[I don't know if there's a better newsgroup for this, but the PC
hardware groups tend to talk about current hardware, and I need
some information about "antiques"...]

I have an old "lunchbox" style portable with a plasma screen,
currently set up as a 486 with 32Mb of RAM, running Linux. It
works OK, but might work better with more RAM. Two obvious
problems: it uses SIMMs rather than the more common DIMMs, and it
only caches the first 32Mb of memory.

I'm wondering if it might be worth trying to put a somewhat newer
motherboard in it, but there are some constraints:

+It must be "baby-AT" size, not ATX
+It must have at least one ISA slot for the special video card.
+The CPU must lay flat on the board-- if it sticks up on a
separate card, it won't fit because the disk drives mount very
close to the motherboard.
+Obviously, no new motherboard meets these specs, so I'm looking
at used ones.

So the first question is, were there any "baby-AT" motherboards
that used DIMMs, or did that come later?

Second, were there any Pentium-class CPUs (maybe from AMD?) that
don't stick up more than about 1.5" from the motherboard
(including the fan)?

I've looked over the ads on ebay, but they often don't give much
information (and most of them are ATX anyway). Also, many of them
are sold without CPUs, and I need to know which CPUs fit which
"sockets". Does anyone know of a good source for this kind of
information?

 

[Jason D.]

On 20 Feb 2004 20:01:08 -0800, rbean@execpc.com (Ron Bean) wrote:

I have an old "lunchbox" style portable with a plasma screen,
currently set up as a 486 with 32Mb of RAM, running Linux. It
works OK, but might work better with more RAM. Two obvious
problems: it uses SIMMs rather than the more common DIMMs, and it
only caches the first 32Mb of memory.

I'm wondering if it might be worth trying to put a somewhat newer
motherboard in it, but there are some constraints:

Plenty of baby-AT socket 7 (this is type of socket for pentium) boards
exists. There is other boards that use so-called super socket-7
(100mhz fsb, used for amd K6/K6-2, K6-3 as well as Cyrix cpus.

Oh, they all have ISA & PCI slots, also all of them have onboard I/O
so need to make sure you get the cables to go with that.

Good boards were HX or TX chipsets ( TX accepts most SDRAM dimms, any
will work even 16 chip 256MB dimms, any speeds.) or 72pin EDO simms).
Avoid VX (will only accept up to 32MB 16chip SDRAM DIMMs and many of
them used EDO SIMMs.) Also avoid VIA. SiS is ok.

Also there were slot 1 baby at boards too.

Stay away PCCHIPS (give-away sign is VXpro, BXpro etc and looks junk).
Good boards, one of them I know is good is Asus, one is P5A, based on
ALi chipset but seems good, DIMM slots. Older Asus was SP97-V
SiS-based chipset but the onboard video part can be manually disabled.
EDO SIMMs only. Both are socket 7 but P5A-B is super 7 as well as
supports older pentium cpus.

Back then we sold awful lot of those computer combos with those.

Best combo was K6-2 333, 400 w/ P5A-B, use 1U heatsink. Even the
newer 1U heatsink for the athlon cpus will fit, just harder to seat.
If you prefer, straighten the kinked part of clip slightly for less
pressure to account for the thicker socket 7 cpus. 1U heatsinks were
designed to be up to 1" max height for 1U rack case.

Cheers,

Wizard

 

[Joe Kelleher]

Ron Bean wrote:

I'm wondering if it might be worth trying to put a somewhat newer
motherboard in it, but there are some constraints:

+It must be "baby-AT" size, not ATX
+It must have at least one ISA slot for the special video card.
+The CPU must lay flat on the board-- if it sticks up on a
separate card, it won't fit because the disk drives mount very
close to the motherboard.
+Obviously, no new motherboard meets these specs, so I'm looking
at used ones.

So the first question is, were there any "baby-AT" motherboards
that used DIMMs, or did that come later?

I've got a PC Chips M748LMRT board that sounds like it meets these specs,
although PC Chips boards are notorious for various problems. For example,
mine has given me trouble with the on-board LAN and UDMA (but all sorted
now). Anyway, this board is 66/100 FSB Socket 370 that is currently running
a Pentium III 700 (it also has a Slot 1). You could possibly use a low
profile cooler designed for the newer Socket 462 with the CPU. The board has
integral sound, video, LAN and modem (although some of these use custom
riser boards), takes PC100 DIMMs and has one shared PCI and ISA slot (ie you
can't use both the PCI slot and ISA slot at the same time).

I'm not suggesting you use this particular board (although it sounds like it
will do what you want) but these kind of boards do exist.


Joe

 

[Ron Bean]

Oh, they all have ISA & PCI slots, also all of them have onboard I/O
so need to make sure you get the cables to go with that.

Are these cables standardized? That is, will cables from one
motherboard fit all the others? There are some attatched to the
back of the case, but they can be replaced.

Thanks for the suggestions.

 

[Ron Bean]

jpero@sympatico.ca (Jason D.) writes:

Good boards, one of them I know is good is Asus, one is P5A, based on
ALi chipset but seems good, DIMM slots.

Best combo was K6-2 333, 400 w/ P5A-B, use 1U heatsink.

This is a good tip-- an ebay search for "p5a" turned up several,
and it looks like just what I was looking for (it appears that
"P5A" is the ATX version and "P5A-B" is the baby-AT version).