> Assembler programming wasn't an unusually exotic skill in the early 70s ^^^ This. Back in the 80s I wrote a 8051 assembler running on a Z80 system. This inv

> Assembler programming wasn't an unusually exotic skill in the early 70s ^^^ This. Back in the 80s I wrote a 8051 assembler running on a Z80 system. This involves a parser, and also a bunch of tables with opcodes, operand formats & so on. Took a number of weeks parttime (not sure if I ever completed it, but the bulk of the functionality was there iirc). This was using just text editor, Z80 assembler, maybe a debugger, and 8051 family datasheet(s). Apart from emulating I/O (as simple or complex as that in emulated machine), difficulty-wise this should be similar to writing an emulator. 8051 and 8080 are not very different in complexity.