On 2021-02-24 11:06 a.m., Jon Elson via cctalk wrote: > On 02/24/2021 08:06 AM, Chris Zach via cctalk wrote: >> >> Sort of. MASSBUS was a very overpriced and to be honest weird system >> that DEC developed in an attempt to be like IBM and charge very high >> markups for generic peripherals. While it did support a variety of >> interface formats (I don't think the RS03 and 04 were SMD, and I know >> the RP07 was *not* SMD) the industry quickly centered on SMD and that >> was that. >> > OOOOhhh, the RP07! I have stories about that drive! > It was a Burroughs mainframe drive they reprogrammed for DEC. It had > a number of issues. > The worst one was that due to some microcode bugs, it was possible to > trash an occasional track descriptor record. When a bad TDR was read, > the drive totally locked up, you had to cycle power to reset it. VMS > recovered from it quite gracefully, however. They finally fixed it, > it required replacing about 10 boards. Then, there was a procedure to > rewrite all the TDRs. The DEC FE assured me it would not touch user > data. Well, after running the procedure, it came up as a blank disk! > YIKES! A quick check at the binary level showed data was still on the > drive, but the RMS-11 home block had been overwritten. Well, I had a > program that could examine the home blocks, and I knew where to find > the backup home blocks. So, I hacked that program to copy the backup > block to the main one, and then change the checksums to agree. > > The other issue is the voice coil could suck dirty air in during long > seeks, so they had ti replace the HDA and put a filter over the air > exhaust from the voice coil. >> Yes, the TM02 and TM03 formatters allowed MASSBUS to connect to >> Pertec drives, but I don't think you could run a tape drive and a >> disk drive on the same MASSBUS channel anyway. Wonder why, >> technically the MASSBUS cable is just an extension of the Unibus, so >> it shouldn't matter much what combination of cables you used. Maybe >> they just wrote different drivers or something. >> > MASSBUS was not anything like a UNIBUS, it was a lot closer to an IBM > channel bus and tag cable. >>> Anybody knows if there was conversion kit to equip CDC 9762 and 9766 >>> type SMD drives into MASSBUS drives much like the TU81 could be >>> turned into a TA81 (SDI)? >> > Well, just the guts inside an RM05, that was a 9762 drive relabeled by > DEC. > Actually the RM05 was a 9766 - the 9762 was an RM03 when DEC re-packaged it
> Jon