Well, the board seems kinda rare.

I already know that this is UNISYS made piece of hardware - just like the one listed here: http://www.ebay.com/itm/Unisys-386-20-MHz-Mot … d-/182169200061

I bouht it and I wonder how good it is.

Board like that are typically pretty early and were very costly especially with the cache controller. Keep it or sell it as it is a nice find and boards like this are pretty rare in the wild.

Will find a nice case for this board and use Sound Blaster Ct-1320a to complete the build.

I guess this beige slot in the center is for some propietary (?) memory expansion.

I received the board today. The thing is insanely large and complex. I did some research and it seems that it came from UNISYS PW2 800 20C computer. Thankfully, the board does seem to fit AT standard so I will probably be able to fit it in some ordinary case.

The board has integrated parallel and serial controller (WD brand). I will try to start this giant this evening and let you know.

For now, I have the following questions:
- what do you think is the socket in the centre of the board? It resambles VLB extension socket, but it's definately not the case here.
- where should I look for any resources, like jumper settings? For now I will not touch any jumpers and dip switches, as I have no idea what they do.
- It seems to be the first revision of the board. Do you think the cable patches are the signs of repair or just some late design changes on early stage of the product? Could be both, but I just wonder.

Just a wild guess, but that board has a distinctive Micronics look to it. Whoever made it, that was definitely a very expensive motherboard in it's day.

That slot is probably a propriety local bus slot for I/O or RAM usage.

Indeed, it was made by Micronics! It's expressly stated on the back of the PCB 😀

I remember Micronics fondly, you've got yourself a Cadillac of a motherboard board to build from.

In my opinion that board would pair well with the biggest AT case you can find, a full-height 5-1/4" ESDI hard drive, and an old Tseng ET3000 or Paradise PVGA1A VGA video board.

Yes it works!

I hooked it up to TSENG ET-4000AX card and it seems to work flawlessly.

There's some issue with memory address, but I guess I'll sort it out.

I just hope HDD will work with current jumper settings (I noticed that even changing memory size requires jumper adjustment). And I have no clue how to adjust the jumpers. I guess I'll ask UNISYS if they could send me some service manual.

A standard AT HDD controller should work fine without needing to worry about motherboard jumper settings. I assume you can set the drive geometry settings in the BIOS menu?

As for the RAM error, I'd suggest re-seating the SIMMs and trying the memory test again. It's a shame you're on the other side of the pound, I've got a box of 30-pin SIMMs and a spare ESDI hard drive controller 😀 There's something about the spin-up sound of those full height drives in high-end early 90's machines that makes me grin...

I replaced the 'Topless' RAM modules (I kinda love the way they look) and the error is gone 😀

I just wish I had an ordinary ISA I/O controller around... last weekend I took almost all of my loose parts to another house, so I'm stuck for now.

The motherboard's BIOS allows you to define the HDD size by their types (1-47 or 60-88 types are supported).

Most of the chips on the board get pretty warm. Wait, even hot!

Unisys allways sold some pretty nice top quality, back in the last half of the 80's.
I have a complete Pw/2 Series-300 system, and it is build like a tank.

I searched for info on the 800 model, and I have found that it had 1mb ram and 40mb
harddrive installed from the factory.

Fun fact... In the movie BIG, Josh is playing a game on the 500 model.

I regret I couldn't get a complete PW2 800, just the motherboard. But as this seems to be standard large AT mobo, I'll live with it.

Looking at the components alone you can tell this had to belong on the high-end side of the market.

I imagine it in some huge desktop case. Need to look for one.

Here is an article from 1987, regarding the introduction of the PW2 line. Yes.... The cases were massive.

https://books.google.dk/books?id=_z4EAAAAMBAJ … s%20300&f=false

Today morning (after about 12 hours from the last power-on) I turned on the board and noticed that it keeps all the settings I have made in BIOS (date, time, etc.).

Even though I did not connect the battery (the board does not have any built in battery. I don't know which chip on the board acts as CMOS, but where does it take power from?

BTW - I'm curious why this particular board has three BIOS chips? I understand one is for general settings and one is for keyboard. I also know that in some computers, like ATARI, there were "HIGH" and "LOW" ROM modules. Is this the case here?

I think I have identified the purpose of the slot in the centre. I was looking at some IBM PS/2 model 70 machine and it seems that it hasexactly the same kind of connector. Easy to find manuals too.

It is described as HDD-bus adapter connector. Whatever that is i found one while googling.