Leaderboard

OK, what you have to note here is the 6561 is a 256 byte x4 whereas the others are 1kb x 4 albeit they have the same footprint. You can tell the smaller RAM machines as they have a 74LS03 instead of a 74LS12 for IC24. These are most likey to be MOD 1 and possibly 2, 3 and upwards use the larger RAM. There are others though that have a daughter board with a 6116 chip and this either plugs into the existing RAM sockets or is soldered directly to the board. You can make your own daughter board up with the 6116 chip (or equivalent) as these are easily obtainable and cheap.