View Full Version : Adding more RAM on an unknown 286 board

August 29th, 2017, 08:12 PM
I'm trying to install more RAM on this board.
Currently it has 1 MB in DIP chips.
I installed 4 x 1 MB SIPP modules, but the board couldn't see them, and still counted to 1024 KB.
Obviously I need to set the DIP-switches, but can't find any info on this board.
Anybody recognizes it and can help?

August 29th, 2017, 08:33 PM
Did you remove the DIP chips before installing the SIPPs? Most motherboards could not have both filled. The SIPPs I can read the label on say its Bank 1 which would duplicate the Bank 1 containing 18 chips. Well, if the SIPP slots work at all and aren't just marketing decoys. Flip it over and make sure there are lots of traces running out of them.

Other motherboards of the era had the choice between 256kB SIPP and 1 MB SIPP in a jumper that was not part of the main switch block if unable to recognize SIPP size. Maybe following traces from the SIPPs could lead you there.

August 30th, 2017, 10:23 AM
So I've removed all 36 DIP chips, but no change - still counted to 1024 KB.
There's only one jumper on this board, next to the 8042 keyboard controller, unlikely to have anything to do with DRAM setup.
So it must be in the 8 DIP-switches block... and if it's just a single bit to change... so I toggled all those switches, one at a time, and after switching #4 to OFF, it counted to 4096 KB, SUCCESS!

As the forum scaled down my image (BTW, is it possible to avoid?), let me explain something more:

Apparently, this board only has two banks:
* empty DIP sockets at the top are marked BANK0 and BANK1
* occupied 36 DIP sockets in the middle are marked BANK0 and BANK1
* SIPP sockets at the bottom are marked BANK0 and BANK1

So I guess no chance to install even more RAM here?

Anyway, if somebody finds the manual for TI-286 or QT-129, I'm still interested.

August 30th, 2017, 10:45 AM
The forum resizes all uploaded images larger than 99k so that they are 99k or less in size. The only way to "avoid" that is to manually shrink/recompress an image to 99k or less file size before uploading it.

August 30th, 2017, 10:53 AM
Glad you got it working. That is a new design to me. So much for relying on it working like other Taiwanese clones.

You would need to locate an expansion card to install more memory. Finding one out of an existing computer is a challenge. However, most of the applications that can frequently use more than 1 MB run quite slowly on 286. 4 MB is adequate if one sticks to what a 286 did well as that should allow you to run multiple applications and have a decent disk cache.