View Full Version : PS/2 Model 25. 286 upgrade board?

February 17th, 2014, 12:49 AM
I won two of these boards on ebay for a song: http://www.ebay.com/itm/161216724012

Originally, I was looking for hard drives, but thanks to ebay's search "features" these boards came up in the search. First glance I thought they were a different revision of the 8086-25. These boards have the exact same connectors & drill holes (and placement) as the 8086-25. I haven't gotten the boards in the mail yet. If tracking numbers can be believed, I should have them Tues. or Wed. Until then I had a few questions/concerns.

1. Is this one of those boards that requires specially wired 30-pin simms?
2. Am I blind, because I don't see an eeprom. Am I missing anything obvious?
3. Is there anything I should get/do before I fire this up? Besides a good scrub?
4. If #1 is true, is there an item number I should look for? Because I do have several IBM branded 30 pin simms in my collection.

February 17th, 2014, 07:02 PM
Now I'm kicking myself... I've seen those boards on ebay for months, but kept overlooking them thinking that they were Model 30/286 boards, which I didn't need.

Oh well :)

I'm still looking for one of the PS/2 Model 25 replacement motherboards from Reply. Not that I NEED one (I do have a 486sx33 Eduquest), but I think it'd be cool to have one of those boards for the Model 25.

February 17th, 2014, 08:12 PM
That does appear to be a Model 30-286 board, because it came with a 3 ISA slot riser, while the Model 25s only have 2 ISA slots.

February 17th, 2014, 08:28 PM
yea, I was looking at that, but all model 30 boards i've seen look like this:

Hopefully I can make the 3-slot card fit. If not, maybe this card will work in its stead: http://www.ebay.com/itm/371001780281

February 18th, 2014, 04:16 AM
yea, I was looking at that, but all model 30 boards i've seen look like this:

That's a regular Model 30 (8086) motherboard (or "planar" as IBM called it). The one in the eBay listing was a Model 30-286 motherboard.

February 18th, 2014, 01:01 PM
Yep, that's a Model-30 80286 board in the auction.

1. yes
2. It'll be around, just not your standard 27256 DIP, I didn't spot it on my Model 30 286 boards either.
3. install some memory (minimum 2x256KB - most of these I've seen had 4 x 256Kb in them) - you'll also want the plug/cable for the VGA connector.
4. hopefully your IBM 30 pin SIMMs work

February 23rd, 2014, 02:07 PM
so, for the record, these are model 30-286 motherboards. I tried to use a model 25 book disk and it errors out, saying I need a model 30 disk.

things i've learned in the last few days:
1. both boards work fine.
2. the ram I have does NOT work. thankfully the 512kb onboard is enough to test everything.
3. the 40mb seagate 157-L that I originally believed to be bad, is just not compatible with the model 25. I'm inclined to believe only 20mb disks work on the 8086 systems.
4. 1.44mb floppy drives work perfectly.
5. the socketed chip between the simm sockets and the onboard ram is the rom.
6. The 3 slot riser is too tall for the model 25 case. I'm probably going to modify it to work. Unless someone can offer me an alternative.

So, I'm in the market for 4x 1mb simms Maybe 8 actually, if the price is right.

February 23rd, 2014, 02:12 PM
forgot pictures!

http://i.imgur.com/CK0Bd1rl.jpg (http://imgur.com/CK0Bd1r)
http://i.imgur.com/7AxSlSql.jpg (http://imgur.com/7AxSlSq)
http://i.imgur.com/ogrtO0Il.jpg (http://imgur.com/ogrtO0I)