Z80 emulator beta for Mac OS/X
 

A few years ago I wrote a Z80 emulator for Mac OS/X as an exercise to teach myself NextStep (Cocoa) programming. It has a front panel GUI and can save/restore memory to a file. It does not have any emulated peripherals.

The front panel looks something like the old IMSAI 8080 FP with several added features bus cycle/instruction cycle step select, an eight Hz slow step capability, A register LED display, and a hexadecimal display of all the primary registers. The emulation runs at about one tenth the clock rate of the host CPU. There is no documentation (yet) other than mouse-over tool-tips.

I'm looking for a couple of beta testers who are proficient in front panel operation and who have an Apple Macintosh running OS/X. If you're interested, send a PM or email and specify PPC or Intel host machine.

z80 caveat
 

I should also mention that I've made a reasonable effort in my emulator to implement all of the undocumented z80 opcodes to allow the widest variety of programs to run. However, some of these undocumented opcodes have different interpretations on differently sourced chips, so of course there's no promise that a particular non standard program will work.

Also, some 8080 code may not work properly on any z80, real or emulated. The original MITS Basic is reported to need patches for z80 operation, and there are surely more suspect programs. The main culprit is dependence on the parity flag bit behavior; Zilog thought that this was "broken" on the 8080, so they "fixed" it on the z80.