8080 Assembler-Text Editor (ATE)

Roy J. Tellason schrieb: Undocumented instrs are not the whole story, particularly not for 8085 vs z80 issues, and especially not for RIM and SIM. I have had hard times finding any 8085 system at all that required and used them; the typical application seems to be a bit-banger RS-232 interface - usually any 808x system that has a serial interface will employ a 8251 or alike for that. Maybe some embedded two-chip system (8085+8355) will take advantage of it, but this is probably only interesting for forensic analyses, not really a hobbyist/conservation issue. No, a really nasty difference comes from the different use of the parity bit in the 8080 vs the same PSW bit in a Z80. Although I thought this would also just be used for calculating/checking the parity bit for bit-banger serial, it often appears in rather obscure scenarios where one wouldn't expect it. At least, in a disassembly one often finds incidents by searching for the JPE/JPO instructions. I know of a least one software (which I had disassembled myself for curiosity long ago) that actually uses undocumented Z80 instructions, namely the ones that allow access to the higher and lower haves of the index registers: this is the 12K-Zapple-Basic by TDL. Concerning these instructions, they seem to work on most common Z80s, including Z80A, B, and H variants, tried those myself. I haven't verified, due to lack of HW, where they also work on the 64180, the z180 or z280. Holger