Re: 6502 illegal opcodes questions

["mdj" <mdj.mdj@gmail.com>]

Michael J. Mahon wrote:

> Errata are always a special case.  The designers always hope that code
> that runs correctly on the original, buggy processor will still run
> correctly on a fixed processor.  In other words, they hope that no
> one has written code that *depends* on buggy behavior.
>
> To summarize, code written to the specifications of a processor will
> work correctly on all implementations, *except* where an implementation
> is faulty.  Code written to work around a fault can still be written
> to the specifications, but avoiding the faulty case(s).

A classic example of this from the real 6502, is the Indirect Absolute
JMP bug. It's trivial, once you know it's there to work around it. But
if you pick a workaround that exploits the bug, your code won't work on
any of the later parts.

Did anyone actually do this? I certainly hope not

Matt