Charles H. Dickman wrote: Chuck, this is good information! After reviewing your supplied info, I got to fiddling with my board. As it turns out, there was a hand-written sticky label (with just the number "225" on it) on the module handle. Must have been some previous owners ID tag. Well, it's old enough that with my handling, it started to fall off, so I just peeled it away. Underneath I found a small, but machine printed, label that reads "44B". Though the etched markings indicate "11B", I must have the same board that you have! With that found out, I was confident in your information and tried the board in an 11/73 system. Sure enough it works great! All 2MB (1MW) is visible and though I haven't run any serious memory tests, STRTRK runs fine under RT11. For the record (and if you don't mind that I borrow your artwork) here are my jumper configurations for 000000 base address; 256Kb chips; 2MB (1MW) memory size; parity CSR at standard; and 22-bit bus: 1 0 | A o== | | B o== 3 | o== 2 | o== 1 | | C ==o b1 | ==o b0 | | D o== 1M | o== 512k | o== 256k | | E o== 21 F ==o | o== 20 ==o | o== 19 ooo | o== 18 | ---| | | ----------------------------- A: 18 bit Q-Bus 1 = 18bit, 0 = 22bit B: Parity Memory CSR Address base address is 17772100 + bit jumpers C: Chip size select b1: bank 1: 1 = 256k chips, 0 = 64k chips b0: bank 0: 1 = 256k chips, 0 = 64k chips D: Memory Size 1M: 1 = 2M, 0 = 1M 512k: 1 = 1M, 0 = 512k 256k: 1 = 512k, 0 = 256k E: Base address 1 = adr bit, 0 = adr bit F: ? I don't know how your F jumpers are set, but mine (as indicated above) don't seem to hurt. Until we can find some documentation, I'm just going to leave them the way they are. (Yes, F1 and F2 are jumpered to the left (1), and F3 is removed altogether.) Thanks a lot! J