PDP-11/05 microcode dump?

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri May 6 17:32:25 CDT 2016

    > From: Mattis Lind

    > Thanks Noel for sorting this out.

Eh, de nada. But thank you.

    >> I wonder if the ucode in the two versions is identical? The uROM chip
    >> numbers should give it, (if they are the same on both versions, albeit
    >> in different locations on the board), but I have yet to check. Does
    >> anyone happen to know?

OK, so the situation here is pretty complicated. To start with / make things
worse, that CPU uses lots of PROMs. Lots and lots and lots and lots of PROMs.

For the data paths board (M7260), both major versions appear to contain the
same PROMs (going by the DEC part numbers), but the chip location (Exx)
numbers are all different.

For the control board (M7261), the C, E ('early' version) and F ('late'
version) etch revisions each contain mostly the same PROMs, but apparently
with slight differences between the sets of PROMs in each (as reflected in
different DEC part numbers). For details see:


to which I have just added all the gory details.

As to getting the contents of all of them dumped in machine-readable form -
oi vey!

    >> on the earlier version (prints for that version are in the GT40 prints
    >> online

It turns out that I have hard-copy prints for the "C" etch revision of the
M7261, which do not yet appear to be online; the GT40 prints have the "E"
etch revision.

I will scan the pages for that revision of the board, and put them up 'soon'.
(I'm not doing the whole print set, it's about 1" thick, and most of them are
for other things anyway, like MM11-L memory, etc.)


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