Date   : Tue, 21 Jul 1992 16:17:09 GMT
From   : micro-heart-of-gold.mit.edu!wupost!sdd.hp.com!zaphod.mps.ohio-state.edu!hobbes.physics.uiowa.edu!iowasp.physics.uiowa.edu!syswtr@bloom-beacon.mit.edu
Subject: Re: Miscellaneous Replies

In article <9207201042.AA09020@LL.MIT.EDU>, sage@LL.MIT.EDU (Jay Sage) writes:
> 
> 
>    On the subject of undocumented Z80 opcodes, Dag Erik Lindberg recently
> wrote, "Zilog recognized that some useful things could be done with those
> op-codes, but flat stated that if their manufacturing process changed, or
> micro-code was modified, those op-codes may not work any more.
...
>    Not at all!  The Z80 was far from dead-ended.  The Z180 and Z280 chips
> have followed it.  Both are Z80-code-compatible.  They are supposed to run
> everything written properly for the Z80.  Thus, they are not guaranteed to
> run programs that used the undocumented codes (and I don't know if the Z180
> or Z280 run those codes or not).
> 
  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...

Willy