I have a couple of 30-pin SIMM RAM pieces. On their labels, it reads:
Z44400DJ
I looked this code up online, and it says:
TI Z44400DJ -70 1M x 4 FPM
What does 1M x 4 mean? Thanks a lot.
Chip density times bus width.
So this is a 4Mbit (512kByte) chip, with 4 data lines. A 30p SIMM is 8b wide, so you'd expect two of these on a 1MB (non parity) SIMM. A 72p SIMM is 32b wide, so you'd expect eight on a 4MB (non-parity) SIMM.
SIMMs can also be double-sided, with the same number again on the other side, so 2MB 30p or 8MB 72p.
You can use these codes both to identify capacity and compatibility - all memory controllers have a maximum supported chip density, and several also have limit on the number of chip per bank. That said, these 4Mbit FP chips are so bog standard it's highly unlikely that any board they fit into wouldn't be able to use them.
Thanks! I should have included a pic, and so here it is!
1MB each then, although there are 3 chips on one piece. Is that for parity? Thanks.
