21 Apr
2006
21 Apr
'06
10:25 a.m.
Holger Veit wrote:
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.
I think I have read that some versions of floating point routines
made use of the un-documented instructions. One version of Small-C
for the Z80 made use of this.
Holger