> which must have been tricky to emulate on the Dec10

I don't see why it would be tricky. I don't know how Allen's 8080 emulator on the PDP-10 worked, but it seems straightforward to emulate 8080 I/O.

Well, I found it a bit hard on my Dec10-based emulator. I never got the memory-mapped stuff to work properly - I just mocked up some of the I/O instructions. But it was actually a spare-time project, intended to let my students do stuff like sorting, searching in strings, so I didn't feel too guilty. It had an assembler, debugger and other stuff. And it was portable - completely standard FORTRAN77!