Mac users interested in Z80 assembler generally download:
WabbitEmu integrates with the WabbitCode and provides you an extensible debugger.
Wabbitcode - An integrated development environment with auto-complete, syntax-highlighting, and comprehensive source-level debugging
The fastest Z80 assembler with extra features supporting TI calculator development
Additional suggestions for Z80 assembler by our robot:
Small C compiler for Z80 ported to Mac06.
to include a Z80 assembler, and a linker...optimizer asz80 - Z80 assembler aslink - linker
