Date   : Tue, 21 Jul 1992 14:56:16 -0400
From   : Jay Sage <sage@ll.mit.edu>
Subject: Undocumented Z80 Opcodes

Willy answered me with:

>> Both the '180 and '280 have expanded instruction sets that make use of
>> the so-called un-documented instructions, particularly in the ED-xx
>> group...

Thanks for the reply, but I did not completely understand it.  I knew, of
course, that the Z180 and Z280 had expanded instruction sets, and I would
have guessed that most if not all of the so-called undocumented Z80 opcodes
would have been used.  The question is, do none, some, or all of the
formerly undocumented codes work on the Z180 and Z280 chips as they do on
the Z80?  If some program authors made use of those undocumented opcodes,
will their programs no longer work properly?

-- Jay Sage