Massbus - was: Re: VAX 11/750

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. 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. I have heard that the difference between what comes out of a MBA (which is huge, several quad height boards in an interface box) and true SMD is the inversion of some differential signals. Whatever it is the changes to a 9762 were very minimal, probably just one of the cards in the card cage. It's quite possible there is no difference, I'll leave that to someone else. My guess is they removed the TM03 formatter from the TU81 and just put in a SDI formatter which was nothing more than yet another closed source version of a Pertec formatter. Maybe DEC lost the contractor who built MASSBUS cables as they were better used to tie ships to a dock. (Yes, I did use a MASSBUS cable to tow a car once. Worked fine) I still have an RM80 drive in my house here, I fire it up every 5 years or so. Mostly for when I get my Decsystem/20 back together. It has the RM80 personality module which is the difference between the R80 and RM80. To be honest I'd bet that one could put an RA81 personality module into it and make an RA80 drive.... Far more interesting would be to see if one could put the RM80 personality module into an RA81 drive and turn that into a 456mb MASSBUS drive. THAT would be interesting.... C