A few months ago, I was digging through some of my dad's old PC parts and found a 286-12 and AM286-20 along with a whole mess of LCC support ICs and a few BIOS chips -including one for a hedland chipset- (looks like they were pulled from 286 boards with socketed CPU+chipset). However, I haven't seen any motherboards, and it's quite possible that the boards those went to are long gone. (otherwise it would be neat to try out a 20 MHz 286 system -actually could be faster than a 386SX-20 or even DX-20 board without cache for 286-compatible software -since the 286 is actually faster per-clock in several important areas)

You cast: "Thread necromancy", Success!

My 286 system is in storage at the moment (have our wedding in a few weeks and also trying to sell the house), but I'd definitely try Landmark 6 when I get it up and running again.

I did eventually replace the surface mount 286 with a PLCC socket in order to try an IBM PS/2 286 to 486SLC upgrade... sadly it never worked, the system still works fine with the old AMD 286 plugged back in though.

I keep meaning to try and pick up a 20 or 25MHz Harris 286 and try that instead.

megatron-uk wrote:

I don't own any of the upgrades - but it's pretty straight forwards really; they all use 386 or 486 designs with a 16bit data bu […]
Show full quote

I don't own any of the upgrades - but it's pretty straight forwards really; they all use 386 or 486 designs with a 16bit data bus (386SX,various Cyrix designs, the IBM 486 SLC2/SLC3 etc). Most come in the form of a small daughterboard that plugs into the 286 socket, which then contains the 386/486 cpu, a fpu socket (and usually some cache) and some glue logic to connect it to the 286 cpu interface, so it's not as though they plug straight in to where the 286 was.

Here are a couple of designs:
http://www.walshcomptech.com/ps2/kingston.htm

Clearly you don't get the full benefit as you are still hampered by the 16bit memory interface of the original 286 board. Still, would've been a nice toy to have! I don't think I'd like to desolder the cpu to fit a PLCC socket in order to get one though!

I wonder if they made clip-on 286 upgrades for surface mounted parts. I know Cyrix did that with their 486SRX chips for 386SX upgrades. (not sure if they ever did that for the 486DRX for surface mounted 386DX boards, though there probably wasn't much point given most of those were AM386DX40s already)

Maybe I overread something but I have a 286 Motherboard (HT12 based) and need an UMB driver to enable UMBs to save conventionel memory.

Does anyone has a this driver or a link to download?

Thanks in advance,
Fabian

P.S: Btw this is the mobo I am talking about:

Bigger version here: http://www.amoretro.de/2012/07/bi-025c-ht12-2 … otherboard.html

Looks nice, doesn't it?

NortonSI shows 11.8 , seems to be on par. I'm curious how to enable "fast ISA".. Landmark shows "20MHz AT".

Another question: Did anyone notice that the Simms in bank 0 get noticable warmer than the Simms in bank 1 ? Very interesting..