On Wed, Dec 20, 2017 at 4:45 PM, Douglas Taylor via cctalk <[email protected]> wrote: > There is a CPU board for sale on ebay, M8189, and it has the usual 3 chips > CPU, MMU, FPU. However, there are 2 extra chips and I've never seen that > before.
https://en.wikipedia.org/wiki/PDP-11_architecture#Optional_instruction_sets Microcode ROMs for the CIS (Commercial Instruction Set)
