Ok I have 2 M00001's if I missed or added a zero or two I'm sorry. Here is my issue. Both do not say 128 on front or back. Both motherboards part numbers end in 0101. Bothe motherboards have different roms. Ram on one board is soldered to the board and the other are chips inserted. The back plastic on one says apple and th other back says Macintosh. I made a boot disk 2.0 finder 4.1 and on the lower left of the window about this says 512k on both units. I am confused. No info I can find on the net to determine if the OS is the issue or it's reading wrong, or they are both upgraded to the 512 boards. I don't know how to tell the difference. Will os 3 tell me more about the Mac? Thanks. Actually I'm pretty happy they both work. 400k disk creation I have found is more an art than science lol.