disassembling Western Digital microcode (PDP-11, WD16, Pascal Microengine)

Eric Smith spacewar at gmail.com
Fri Dec 25 03:25:14 CST 2015

On Fri, Dec 25, 2015 at 2:10 AM, Paul Birkel <pbirkel at gmail.com> wrote:
> Report back with your findings :->!

OK. I'm really much more interested in the Pascal Microengine
firmware, but I'm starting with the LSI-11 because it's the same
chipset and better documented, so I can more easily gain practical
experience with its microcode, then move on the the PM.

At first I thought the microinstruction example in my previous email
was to decode the 000000-000007 (octal) instructions, which are HALT,
WAIT, RTI, BPT, IOT, RESET, RTT, and unused. That's possible, and it
may make sense that RTI and RTT jump to the same routine, but it seems
unlikely that the unused opcode should jump there.

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