On Sun, Jan 8, 2017 at 6:46 PM, Robert Armstrong <b...@jfcl.com> wrote: >>Tony Duell <ard.p850...@gmail.com> wrote: >>R80 the lines are outputs from the drive giving the coding of the ready lamp >>cap > > I was always thought that the R80 had to be unit #0 to function, but I admit > that I've never tried > anything else. I wonder if that's not true?? The RL02 drive(s) on the IDC > can be any of units > 1, 2 or 3.
I don't know about the 11/730's IDC. I was just looking at the R80 schematics, the unit number lines are output on the 60 wire cable. Maybe the RM80's massbus box uses them or something? A quick look at the printset and technical manual suggests that the 11/730 IDC compares the drive select number from the appropriate output register with the unit number from the R80 (set by the ready lamp cap). If they match it uses the R80 logic, if not then it uses the RL02 logic. I have no idea if the nomal software will work if the R80 s anything but unit 0, but it looks like the hardware was designed to allow for it. > >>The HDA is the only major unit I can't repair (yet!). > > Yeah, same here. In addition to the 11/730 with one (dead) R80, one RA81 > and one RA82, > I have a MicroVAX-III with an RA82 drive. Keeping them all working has been > a real challenge. The only (other) SDI drive I have is an RA60, and I have no packs for it. I doubt I will ever use it. > Fixing the electronics and mechanical parts isn't too bad, and I have plenty > of spares, but the Apart from the ROMs (and those 8355s/8755s are not suported by most programmers/readers now available), there are no custom parts on the PCBs that I've spotted. There are custom chips on the PCB on the front of the HDA and unlike one Micropolis drive I work on, you can't replace them without dismantling the HDA (in a clean room). There are also plug and socket connectors on that PCB -- inside the HDA. I hope those don't suffer from bad contacts! > HDAs don’t seem to be very reliable. I get the impression that they were > designed with a finite > number of spin up/spin down cycles in mind, and once you exceed that limit > they die. Fortunately Quite likely. Which means we are less kind to them than we should be in that we don't keep them running (or at least I won't) > I've been able to find spares for the RA81 and RA82 HDAs, but R?80s seem to > be pretty rare. -tony
