What Makes a PDP-11/35 or 40 Tick?

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Jun 12 10:11:19 CDT 2019


    > From: Liam Proven

    > This is what makes a PDP-11/35 or PDP-11/40 tick. It turns out to be
    > 441 ICs.

I wondered if it was fair to list the DEC 23B00A2, etc that hold the ucode
as separate parts; they might have been a bunch of 256x4 PROMs, and the
separate part numbers were just for the different programming. (Whether
differently programmed PROMs count as 'different' parts for the purposes
of this table I leave aside.)

Looking at my M7232 card, though, I think they may be masked ROMs; the
only part number on them looks like a manufacturer applied one with the
DEC number.

Interestingly, about a third are MMI parts, and the rest are NS. I wonder
if neither manufacturer had enough capacity alone, or if DEC just wanted
multiple sourcing. (The parts appear to be basically the same, in terms of
speed, format, etc so it appears either could have provided any of them,
modulo the programme.)

	Noel


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