Date   : Mon, 05 Sep 2005 12:41:52 +0100 (BST)
From   : Tom Walker <tommowalker@...>
Subject: Re: Beeb games using illegal 6502 opcodes

Repton 2 uses ANC # at one point, though I'm unsure as
to whether it's a bug or space-saving. It at one point
executes the following bit of code :

asl a
asl a
rol $0B  (ANC is $0B)
asl a
rol $0B
asl a
rol $0B
sta $0A
etc

but calls right into the middle of it, after loading A
with 0. It has the effect of skipping an ASL and
loading the carry with 0.

I also remember Android Attack using loads of
undocumented NOPs, though I'll have to check that.

Tom


               
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