Never heard about it... if you can get the pinouts it should be possible to make an ATX->AT adapter with the auxiliary connectors. I wonder where the 5VSB rail is supposed to go.

Was the board from an OEM system, though? This looks like something that would happen in an OEM system (that does not have to adhere to standards like retail stuff). Or else how would AT PSUs with those connectors behave when used with regular AT motherboards?

That's what I thought, but it's an Intel motherboard and works fine in the standard AT case it came in (was bought new in late 1996.) It still has the normal connectors, these ones are just extra.

The PS_ON connector is three pin, so I'm guessing +5VSB, GND, and the PS_ON signal.

I was also thinking you should be able to make an ATX adapter for it. It really does look like it was an experiment for what later became ATX.

Of course the problem is I am rebuilding a computer I once owned, getting it back to its original state, so having soft-off won't make it the same as it once was...ah the conundrum of building retro PCs 😀

Model numbers would help.

Tell me about it - these old Intel boards are terrible to try to identify. The PSU is a Minebea Electronics AF000151, but I'm not sure that's particularly useful, does it help?

EDIT: To be clear, I do have the motherboard manual somewhere, I am still looking for it. Once I find that it should shed some light on both the model and the pinouts.

Malvineous wrote:

Tell me about it - these old Intel boards are terrible to try to identify.

Harder, but usually not impossible.
- What is the AA number?
- What is the BIOS string?
- Have a photo?
.

Malvineous wrote:

The PSU is a Minebea Electronics AF000151, but I'm not sure that's particularly useful, does it help?

Yes. Found a photo. Now I know what this AUX connector looks like.
Is the one like used on a 3-pin fan - yes?
.

Yep it's the same connector used on a 3-pin fan (that's what I meant by "3-pin connector, same style as a fan connector" in my first post.)

I've attached a photo of the board. Not sure of the AA number, perhaps you can spot it? There is a "CA" number, I'm not sure if that's it.

BIOS string is just AMIBIOS BIOS Version 1.00.06.CB0 - there's no other identifying information shown.

Malvineous wrote:

I've attached a photo of the board. Not sure of the AA number, perhaps you can spot it? There is a "CA" number, I'm not sure if that's it.

That's it. Here is a screen shot of a different example of the same board where the stickers were placed better.
You can see the AA on the board's silkscreening.

(As I understand it.)
The AA number gives the basic part number and minor revision.
The PBA number shows any major revisions or customizations for OEMs (Like Dell/HP/Gateway).

Malvineous wrote:

BIOS string is just AMIBIOS BIOS Version 1.00.06.CB0 - there's no other identifying information shown.

The "CB0" gives away the model. -- It's an Intel Advanced/EV (aka Intel Endeavour)
http://www.elhvb.com/mobokive/Archive/Intel/A … EV_28183501.pdf
http://www.elhvb.com/mobokive/Archive/Intel/A … pd_28182506.pdf
In the first PDF see page 25 about the power connectors and soft-off.
Also see page 17 about your keyboard port.
They came either way (AT or PS/2 style) which is why your board doesn't exactly match some photos of this model you see online.
.

Wow, well found, thanks for that! No wonder I couldn't see the AA number. I remember struggling years ago when attempting my first BIOS reflash but it was so long ago I forgot where the AA number ended up being!

That explains what the connectors are for then. How interesting it doesn't have +5VSB. I wonder how it switches the PC on? Maybe the soft-off power button connector is directly connected to PS_ON somehow, but being a momentary switch there must be some latching circuit somewhere. Intriguing.

Thanks again!

Hum... so it doesn't have +5VSB? Maybe its something like my Compaq Deskpro 5200MMX: the PSU is directly connected to a momentary switch that turns it on and off, all the latching is done inside the PSU.

alexanrs wrote:

Hum... so it doesn't have +5VSB? Maybe its something like my Compaq Deskpro 5200MMX: the PSU is directly connected to a momentary switch that turns it on and off, all the latching is done inside the PSU.

That's what I'm thinking too.
I suspect there is a vsb rail at some voltage but it's all internal to the power supply.
.

Next time I have the case open I plan to put a multimeter on the PS_ON pins and see if they get connected together when the S.OFF button is pressed.

Also, thanks for the reminder. I think the PSU with the matching connector was from a Compaq Deskpro system as well (forget the model number, long since thrown away.) I was wondering where it came from...

I had an pentiuum 133 computer that used an AT power supply and the system itself could power on/off "by software".
There was a limitation that was the system would instant off if pressed the power button, but it didn't showed the "your're safe to turn of your computer" message.
idk how that thing actually worked, but, the power button was connected to a kind of controller with short cables, and the switch on/off cable from the power supply was connected to that board, I think there was something more pluged into the motherboard too but I can't remember 🙁 .

That computer was actually a special computer, it had some alarm stuff behind the case, and a BIG pc speaker, maybe it was used for security, and when some signal from the alarm conector behind was activated, the computer would turn on doing alot of beeps.
EDIT: I found some pics of that machine over the internet
http://leonelfraga.com/imagens/neomatrixtech/infoway_4.jpg
http://leonelfraga.com/imagens/neomatrixtech/infoway_7.jpg
http://leonelfraga.com/imagens/neomatrixtech/infoway_2.jpg
http://leonelfraga.com/imagens/neomatrixtech/infoway_3.jpg