Hi Tony,
Mike Riley's RcAsm has a .def file for Z80s, so you can use that if you wish.
There is an assembler called asmx (available on Herb's retrotechnology site) that can handle Z80 instructions as well as 1802 of course.
My usual goto Z80 assembler is zmac.? There are a couple variants around on the web, one source is .
Of course there are many others out there, but those are the ones I use most often.
-Bob
