Tandy T100 info

substrates with 4 off 2K*8 static RAMs soldered to them. There were separate chip select pins for each RAM, all the address decoding was on the mainboard. These modules were 0.7" (I think) wide. But it's possible, with a bit of careful bending, to get a normal 0.6" wide IC into the socket. You can put a nromal 8K*8 static RAM into the top 12 pins of each side of the socket (wiith pins 1,2,27,28 of the RAM haning off the end) and most of the signals match up. I did this in my Model 100. I then did some cut-n-jumper mods to get A11 and A12 straight off the address bus, to modify the address decoder appropriately (while still keeping the original 8K module in the lowest address possition), and to handle the power-down memory protection. I should still have notes on this, but I was working on a UK model, which doesn't have the intenral modem, and where different sections of ICs are used in some positions (what I mean here, is that if the US schematic shows, say, U6a as a '00 NAND gate in some position in the circuit, then the UK version still uses a '00 NAND gate, but it might well be U21c (the component references are totally ficticious here!)). -tony