PDP-11/84 Qbus slots for memory
Noel Chiappa
jnc at mercury.lcs.mit.edu
Sun Jul 22 12:54:25 CDT 2018
> From: Mark Matlock
> With the 11/83 the position of the memory board ... above the CPU uses
> PMI
Yes, through the C-D interconnect; described in detail here:
http://gunkies.org/wiki/CD_interconnect#Use_by_PMI
The 'above' is because the CD interconnect is not a true bus, it only
interconnected pairs of slots.
> In the 11/84 the CPU is above the MSV11-JE memory
The PMI is still on the CD connector in this machine, but the PMI is wired as
a true bus on the backplane, allowing that ordering.
> there are 3 Bus slots in the 11/84 above the Unibus map board, would it
> be possible to put a dual width Q22 I/O board in the second memory slot
> (not the PMI side of the slot) and have it able to DMA into the
> MSV11-JE?
It is speculated that this should be possible, but there are jumpers on the
backplane you'd need to pull. See the writeup here:
http://gunkies.org/wiki/PDP-11/84#QBUS_slots
Noel
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