11/70 board set on e-bay. . .
mcguire at neurotica.com
Tue Jan 15 10:31:34 CST 2008
On Jan 14, 2008, at 10:02 PM, Richard wrote:
>> The 11/70 CPU is *not* a unibus backplane. It is a *very* large
>> backplane that fills an entire BA11F.
> Interesting, I just assumed it was unibus. Is the /70 the only PDP-11
> that has a custom backplane? I thought the PDP-11 family had standard
> backplanes: unibus and Q-bus.
No, (most) PDP-11s have standard *peripheral buses*, Unibus and Q-
bus. In fact, most (all?) Unibus PDP-11s have backplanes that are
specific to the processor being used, as nearly all of them are multi-
board sets (LOTS of boards in the case of the 11/70) and the card-
edge connectors carry processor-internal signals, not high-level
Some PDP-11s have their memory on the Unibus or Qbus, and some
don't. The 11/70 (which I mention because that's what started this
thread) does not.
Some of them are "close relatives" like the 11/04 and 11/34, which
share the same backplane. In those systems, for example, the first
few slots are not Unibus, but carry CPU-internal signals. Later
slots are Unibus.
Qbus PDP-1s are more standardized across the product line. Most
(all?) of them use an all-Qbus backplane and the CPU is contained on
Port Charlotte, FL
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