I'm also posting this response to classiccmp in case others are interested in some of the details.... You wrote... The media is still in transit, I haven't got it yet. He said it was on 7900A disk cartridge, but he might also send it on 1/2 tape. It will start out life running on two 2100A's. Then it will migrate to either my 2109B/2113B or if that fails the 2117F's. Eventually it will also run on a Unix or DOS/WIN PC via an emulator. The 7900A is 5mb (2.5 fixed, 2.5 removable). The 7906 is 20mb (10 fixed, 10 removable). Only the very earliest versions of TSB used a Drum; since the Access version is the last version of TSB ever made, it will run fine without a drum (probably can't use a drum either). Even if I ever got a drum unit, I think that would be beyond my capabilities to repair. The 7900 uses a 12940 cartridge. This is a single platter, 24 hard sector cartridge. It has a raised area on the top that opens to accept the heads when inserted into the drive. From what I understand about RK05's, the disk cartridge is mechanically/cosmetically similar. The 7906 uses a similar cartridge (12989), but there is only one sector notch on the hub instead of 24. The 7920 (which I'm not really familiar with) I think used a 10 platter top loading cartridge. PS - I might have 12940 and 12989 interchanged above - poor memory :) Also, I don't recall the mils measurements, but the internal media platter is a different thickness between the 12940 and 12989. The 7900 drive hooked up to a 13210 controller in the cpu backplane. You could daisychain 3 more drives off the main 13210 controller. The 7906 used a different arrangement. In the cpu backplane was a 13037 card, which went to a rackmount box called a 13037 disc control unit (about 5 inches tall). Cables from the 13037 went to each 7905/7906/7920 drive. ISTR that the 13037 disc control unit (rev C at least) could support up to eight drives, and could support two separate computers. It also supposedly supported HP-IB drives too (but I don't think TSB would use the HP-IB drives, even through the 13037). I haven't settled on which systems I'll run it on yet (2100, 21MXE or 21MXF), Because I haven't, I will likely have some equipment left over from my scavenging. If so, it will be offered on classiccmp. Mucho Appreciation! Jay West