> On the 80x86, there's another cool trick=20
> Where it allows 3 different  entry points to the same code...=20

The 6510 has quite a few undocumented opcodes that the really
nerdy thought would bewilder casual users. For example there
were several that could be strung together in the middle of bona
fide-looking ML which looked like data (came up as ??? in a
disassembly) and looked nonsensical. But one function was to
actually operate as a computed branch and NOPs. So you
could appear to jump into the middle of a series of data bytes
without a crash, ending up in a common routine from one of
several entry points

Some opcodes were seemingly useless or innocuous, like one
that just did LDX $#0A, or LDY (X),Y. Some were NOPs,
like the official one, $#EA

Others were not so cool. There were no opcodes ending in 2
(02, 12, ... F2). If you happened to execute an x2 byte the
processor/machine would just freeze and only a h/w reset could
get you out of it

Joe
--=20
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