Tony wrote:
Unibus and Qbus use the same double-sided 36 pin
(18 pin per side) 0.125"
pitch connectors. Q bus boards are normally dual or quad, Unibus are
normally quad or hrx.
To be overly pedantic:
Unibus boards are normally dual. The only real Unibus boards you're likely
to find are the terminators and bus jumpers. If someone tries to tell you
that a quad or hex board is a Unibus board, they're almost certainly
mistaken, and it is probably really an SPC or MUD/SPC board. Normally
the only Unibus slots in a PDP-11 backplane are the A-B positions of the
first and last slots, though there are exceptions to that in various
places such as the PDP-11/45 and RH11 backplanes.
Overly pedanyic, yes....
Since the signals on an SPC slot are essentially those on the backplane
interconnecting slots (which is what you're calling Unibus), I think it
would be reasonable to say that the SPC boards are Unibus devices.
Certainly DEC manuals do this (they talk about a Unibus serial board
which is actually an SPC board, etc).
-tony