dumping Western Digital Microms (PDP-11, WD16, Pascal Microengine)

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Dec 21 10:48:32 CST 2015

    > From: Eric Smith

    > So far I have dumped the following LSI-11 Microms:
    > 3010D, DEC P/N 23-001B5 (also designated CP1631-10) - addr 0x000-0x1ff
    > 3007D, DEC P/N 23-002B5 (also designated CP1631-07) - addr 0x200-0x3ff

Excellent work!

I was going to point out that there is another uROM (KEV11) for the LSI-11,
for the EIS/FIS, and also that there is some variation in the numbers of
the uROM chips, but along the way, I ran into a puzzle.

DEC documentation differs on the location of the two uROM's in the LSI-11/2
(KD11-HA, M7270): the 'Microcomputer Products Handbook' gives the order (from
the handle end) as KEV11, uROM 1, uROM 0, Control, Data Path; the print set
for the KD11-HA gives KEV11, Control, uROM 1, uROM 0, Data Path!

>From which I conclude that either: i) one of the documents, perhaps the
Handbook, is wrong, or ii) the 'Control' chip must also be a uROM, and that
there is some variation in how the 3 chips can be plugged in?

Here is more data from a couple of boards I have access to (from the handle

- 2007C 23-002C4, 3010A 23-001B5, 3007D 23-002B5
- 2007C 23-002C4, 3010D 23-001B5, 3007D 23-007B5
- 2007C 23-003C4, 3010D 23-008B5, 3007D 23-007B5

Anyone know what's up here? 

Getting back to the KEV11, the one I have seen is a 3015 23-003B5.

    > the control chip also contains PLAs that can force microcode jumps under
    > various conditions despite there being no corresponding jump instruction in
    > the Microms.

Hmm. Any idea/way to read them out?


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