PDP-11 Memory

[Allison Parent]

Most Probable cause is interrupt grant is broken.  For most microspheres backplanes the first three slots are different than remaining.


Phoned this in!


On Jan 11, 2019, at 12:28 PM, Bill Gunshannon via cctalk <cctalk at classiccmp.org> wrote:


Well, it has been so long since I had to put together an
entire system I forgot what fun it can be.

With almost documentation I was able to configure 4 1meg
memory modules and I tested them all in my 11/23+ box.


KDJ11-B with 4 different (but similar) memory cards.
"MAP" option of the KDJ11 shows 4 meg (minus the I/O
Page) and all the right CSR's for the first four blocks.

Really wanted to make this a deskside so I moved the
cards to a MicroPDP box (Yes, I have a coule of the
deskside pedestals).  Power on, Memory CSR error.
Move then back to the 11/23+ works fine.  If I only
put the first three in the MicroPDP box it works.
But as soon as I try to put in a fourth module I
get the memory CSR error.  Tried different cards
(although working in the 11/23+ box would make me
think it is not a problem with the card) no help.

Anybody care to take a stab at what might be causing
this problem?

bill