Apologies if anyone already got this; I originally posted it during what seems to have been an outage, and I assume the original is lost... On Feb 5, 20:19, Chuck McManis wrote: ^^^ ete? :-) Nope, Pete was wrong again. It looks like MSCP support first appeared in 4.0. And I never did get my RQDX3 to work under RSX-11 (but I never had a version later than 4.2). can I've never done an install from tape, except to recover a backup, and then what matters is what standalone BRU or DSC supports. In 4.2 at least, BRU and BRU64K.SYS (the standalone) do support MSCP, but the manual only lists RA80/RA60/RA81/RC25/RD51/RX50 disks (and no MSCP tapes at all). DSC only supports the RA80; standalone DSC has no MSCP support at all in 4.2. I'd expect 4.0 supports even less. The list above implies RQDX1 support and other things, but not RQDX3. That might be a problem, because I think there's a bug in the early DU: handler that prevents it working with RQDX3s. I certainly never got RSX-11 4.2 to work with any RQDX3, and the same bug might apply to a 3rd-party controller. Best way to find out is to try it. I reckon there's a reasonable chance it will work, especially if your disk controller works with RT-11 5.1. In RT-11, full MSCP support post-dates even 5.1. 5.1 works with RQDX1/2, but not RQDX3, for example; because whoever wrote the DU: handler ignored the MSCP documentation and made an unwarranted assumption about the contents of the SA register during initialisation. It took me ages to trace the problem and fix it :-). -- Pete Peter Turnbull Dept. of Computer Science University of York