compuadd 212 switches

[286user]

I have a compuadd 212 286 12mhz that Im trying to find out the dip switch settings for. I recently posted about a 386 version of it in my collection, well here's another version but the 286 one. I want to add an 287 xl math co proc to it as well as upgrade the ram. I know on the 386 it can go maybe to 4mb, well this one has 4 simm sockets 30 pin as well and from what ive researched or googled cant find the amount this one maxes at. In addition same thing I think one of those switches controls mem size and co proc being present, but I havent figured out or found the dip switch settings.

Thanks in advance.

 

[krebizfan]

Could you provide a picture of the motherboard and read the names on major support chips? Look for things like Headland or Chips & Technologies or abbreviated versions of same. I think that Compuadd used at least three different motherboards with 12 MHz 286s. All of them were commonly available imported motherboards so identifying the actual manufacturer model will lead to the jumper information from TH99 or Stason.

The earlier SIMM system only takes 256kB simms which maxes out at 1MB; the last one made could also take 1MB simms leading to a 4MB max.

 

[286user]

Sorry ill post pics by the weekend. From what i can remember the board took up to 4mb. The reason why is over 6 yrs ago i was playing with it, and managed to put 4 1mb simms in as at the time it had only 1mb total. Back then i had written down some of the dip switch settings, as i had done it by trial and error. One of the times i had the system running i put the 4 1mb simms in and it kept beeping, then i figured out what switch i set to on or off then all of a sudden i had 4mbs total. In my quest to try even more i think i even tried 4 4mb simms as i thought that a 286 should easily handle 16mb due to the memory address limits.
Either way, i dont think 16mb worked, but 4 did. The only thing is i put it up and just recently wanted to mess with it. Now i had written down some of the dip switch settings but seem to have lost or misplaced them. I would be happy just getting 4mb back on it, and a 287 math co pro i recently acquired. I want to set this up as a unit to play with windows 286, and maybe os2 1.3.

Thanks

 

[krebizfan]

The 286 has 24-bits to handle physical memory in protected mode which translates to 16 MB, slightly less will be available for use. The motherboard is probably limited to 4 MB but if you could find a memory adapter card you could install additional memory. I had an AST expansion card that could handle 8 MB plus another 8 MB on a very expensive daughter card. Install that combination and wind up with 1 MB conventional RAM, 15 MB XMS, and 4 MB that have to be converted to EMS because they can't be used as XMS. Makes for a nice setup if planning to run Lotus 1-2-3 v2.2 for DOS under Windows 3.x. Well, from a system memory standpoint at least since there is more than enough memory for both Windows and Lotus but DOS apps were inconvenient when run under standard mode Windows 3.x

I had access to several CompuAdd 286 systems (my own and ones bought on my recommendation). I don't have the documentation anymore. Didn't expect to ever need it again. I did see several different motherboards.

Note: Windows 286 does not use XMS directly except for the 64k HMA unless that is used by DOS. Some applications could be designed to store data in XMS but Windows 286 itself swaps code segments into EMS. Win 3.x needs lots of XMS for standard mode but a small amount of EMS is helpful for certain DOS apps. OS/2 1.3 is all about the extended memory. Yes, this does mean you may have to go into either setup program or BIOS and change the memory settings to alter the amounts of XMS and EMS available every time you switch OS.

 

[286user]

attached are some pics of the motherboard, to help identify it. I'm still trying to figure out the switches, especially so
I can goto 4 mb ram and install the 287 math coprocessor.

Thanks in advance