Very good !

By the way if you're not scared by a soldering iron you could easily upgrade it to 8 simm slots instead of just 4 sipp ^^

Having a 286 with 8MiB RAM would be awesome. I had my 286 once to 4MiB, which is already quite neat and insane. But 8MiB? You could run OS/2 1.x on it! 😀

Hehe, you only need to install enough RAM-cards and can upgrade to 16MB:
Re: Profex "PC 33" - Suntac 80286-12

I have a RAMpAT! card which should support 16MB on a single card but its not working..
Acculogic RAMpAT! - Anybody with a working card here?

My octek panther (which is 386 based but seems to be capable of running 286s too) can apparently support up to 32MB of ram !! http://www.win3x.org/uh19/motherboard/show/5377

That is insane xD (and yeah the CPU would probably only access the top 16MB directly and the rest through EMS)

Would be interesting to see that board whith a 286..! Can it really handle 16 MB XMS + 16MB EMS? I assume for the EMS a device driver is needed which may run only on the 386.

I really don't know, it only has 2mb installed at the moment and I just have one set of 4 4MB sticks (I guess I can get it to 20MB)

Predator99 wrote on 2020-10-01, 08:50:

Would be interesting to see that board whith a 286..! Can it really handle 16 MB XMS + 16MB EMS? I assume for the EMS a device driver is needed which may run only on the 386.

I've already seen a 80386SX machine with 8 SIMM slots, powered by the VLSI TOPCAT chipset. I tested it with 32MB of RAM, and I can get 16MB XMS + 16MB EMS indeed. I also saw similar capabilities in the datasheet of the HT25 chipset (which I once had in a 486SLC2-based laptop). Actually, you can configure the TOPCAT down to 256KB conventional RAM and nearly 32MB EMS alone. I hacked the Lo-Tech EMM driver to adapt it to the TOPCAT chipset: https://github.com/karcherm/topemm

8MB 286 😜. Now that's an insane amount of ram! Sounds absolutely lovely though for a tricked out AT.

Out of curiosity. Does anyone know if 286-20 board have the right crystals out of the box for a 25mhz upgrade or if you need to swap some chips too like for the slower speed boards?

SodaSuccubus wrote on 2020-10-01, 21:03:

Out of curiosity. Does anyone know if 286-20 board have the right crystals out of the box for a 25mhz upgrade or if you need to swap some chips too like for the slower speed boards?

I don't remember seeing any 286 or 386SX board with jumperable clocks, so most likely you have to swap crystals to upgrade. On the other hand, as 286-20 boards are quite late, they might exist with multiple oscillators (as seen on some 386DX boards) or a multi-frequency clock synthesizer chip (as seen on most later 486 boards).

If a specific 286-20 board has a 40MHz crystal or oscillator installed, but no 50MHz crystal or oscillator, you definitely need to swap the oscillator to upgrade.

The pcchips M396F has a switchable frequency (between 33 and 40MHz), but it's a really late motherboard.

Sooo update.

Another set of 4x1mb came in today, plugged it in. Nothing.

Blackscreen. Monitor goes "out of range" and nothing happens. Tried resetting it, trying different SIMM sockets. No dice. If I put in my old 2x256k it' usually boot after some reseating.

This ram was sold working soo, I guess the board doesn't like it either? I dunno. I'm kinda done with this board TBH. Maybe trying some actual sipps would do it. But I kinda feel like at that point I'd be better getting a proper SIMM 20mhz board.

Oh well.

One of my 286 and a older 386 do not like any gold plated simms but they have soldered simm sockets. They both work great with the tinned 30pin simms. Think their sockets just do not contact well with the harder gold plated ones, yes the solder tinned ones have softer contact surface so older sockets seem to deal with them better, less reseating. Think that is why most 72pin simms are tinned not gold plated, not just for the cost but actually do make better contact IMHO