Pdp cpus

Eric Smith spacewar at gmail.com
Tue May 5 13:14:04 CDT 2020

On 5/2/20 5:10 PM, Kevin Lee via cctalk wrote:
> Interesting stuff
> https://github.com/1801BM1/cpu11

On Sun, May 3, 2020 at 4:23 AM Al Kossow via cctalk <cctalk at classiccmp.org>

> Eric Smith's work on the WD CP1600 chipset's
> various microcode


I've verified that the microcode dumps of the Soviet 581 LSI-11 clone* are
identical to the DEC microcode. That's not particularly surprising, but it
does give me confidence that the control chip PLAs should be identical as
well. Since they have decoded the control chip PLAs, I should be able to
use that to update my LSI-11 microcode disassembly.

John took photos of the LSI-11 control chip for me, but I had somewhat more
difficulty reading the PLA bits than I did with the WD9000 (Pascal
Microengine) control chip, so I didn't complete transcribing the LSI-11
PLAs.  I haven't really looked at the WD16 microcode or PLAs yet.

* The multi-chip clone. The 1801BM* single-chip PDP-11 microprocessors are
not directly based on any DEC design.

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