On 01/06/2016 18:50, Henk Gooijen wrote:
-----Oorspronkelijk bericht----- From: Noel Chiappa Sent: Wednesday,
June 01, 2016 7:24 PM To: cctalk@classiccmp.org Cc:
j...@mercury.lcs.mit.edu Subject: Re: PDP-11/94-E
> From: Henk Gooijen
> The first 4 (5?) slots are QBUS
Technically, PMI, which is more-or-less QBUS on the left (A/B) side
(modulo
not having grants, unless the appropriate backplane jumpers are set to
send
grants to those slots), and it uses the standard CD interconnect (as
in Q/CD
backplanes) on the right (C/D) side to carry PMI.
> The RX211 must have the NPR/NPG open. Check the documention which
DIP
> switch must be set in the correct position. However, not sure if
that
> would cause the RX211 to be "invisible".
Right; DMA would not work, but normal master/slave UNIBUS read/write
cycles
to the device registers should still work.
Noel
---------
You can of course read and write the CSR and all other registers of
the RX211,
You could if you were able to get into ODT. I have yet to discover how
you get there.
*if* it is in the memory space where you expect it. Making sure is
easy: check
the jumpers / DIP switches on the RX211.
Note that the RX11 (for RX01 drives) does *not* use DMA, and what's worse
(IIRC) that module does NOT jumper CA1-CB1 on the module itself!
The RX211 does use DMA, so the NPG should be open. As said, there is no
need to cut the NPR/NPG wire, because those two pins go to that first
module
at the right side, and has a DIP switch to open / close the NPR/NPG
for *all*
UNIBUS slots).
But this is all from memory ... you can read the manual from bitsavers
too ;-)
BTW, yes I have an 84 and an 94 in that box (power supply at the right
side
of the box). Very similar in all aspects. In fact, DEC did "rebrand"
an 84 to
an 94 by swapping the CPU module (and removing the memory modules),
and glueing a label saying PDP-11/94 over the original panel's PDP-11/84.
I have such a box too. Hmmm, should take a picture of that ...
- Henk
