I have discovered out how to make a standard 2 Meg or 1 Meg 30 pin SIMM work in the T3200sx.
What you have to do is cut the trace that is connected to the CASP line (pin 28 ) and connect that to the CAS line (pin 2). This will result in a 1 Meg module that will work with out the parity error that you will get with out this modification. I have noticed that your 2 Meg Toshiba SIMMs have only 4 chips on them instead of the usual 9 or 3. It would be interesting to try and find the datasheet for the chips and try and figure out the pinout of a 2 Meg Toshiba SIMM. In my T3200sx my 2 Meg modules have 6 chips and I have only been able to find the datasheet for 4 of them. I think that the other 2 are the parity chips but I am not sure. I have found out that pin 19 is grounded on the 2 Meg Toshiba SIMM. I am also guessing that pin 28 on the 2 Meg Toshiba SIMM is A10 but I am not sure.
Then i "discovered" that modules that don't work by themselves can be mixed to the others and they will work anyway.
The reason the modules need to be installed in pairs is because the 386SX has a 16 bit data bus. 30 pin SIMMs are only 8 bits wide, you need two of them to make up the 16 bit bus.
If you had a 386DX, you'd need four 30 pin SIMMs to make up the bus, though some chipsets had a mode where you could limp along on two modules at the cost of speed.
I expressed myself incorrectly sorry for my English is not very good.
What mean to say is that a type of SIMM module that will fail to work using two identical types of this same incompatible simm, may work if mixed to another SIMM that worked in identical pairs.
Not sure why this happens, but i have good look doing this to expand the ram.
Very nice. That looks beautiful. Any chance of some pictures of just text based programs running? Maybe Microsoft edit? That one gives me headaches on mine.