[HECnet] Drives for a VAX-11/730

[John Wilson]

From: "Bob Armstrong" <bob at jfcl.com>

As I remember, the RM02/3/5 were CDC 9760-something drives, which were SMD.
Of course it's possible that the DEC OEM versions had customized interfaces.

Yes, DEC made a bunch of gratuitous changes, although it might be possible
to duplicate them with another drive.   IIRC they reversed the polarity of
most/all of the signals on one cable (it's differential so you can fix that
by swapping wires), and the direction of the unit-select lines is reversed
(so the plug in the drive tells the RM adapter what Massbus unit to be,
rather than telling the drive what SMD unit to be).   I think there are
a few other things but the basic I/O interface is the same.

My 11/730 has a UDA50 + RA81 instead of the RB730, and was bootable last
time it was anything-able, FWIW.   So I'd think a CDU720/etc. would work
fine too.

John Wilson
D Bit