Re: [stella] Games using unofficial opcodes

Subject: Re: [stella] Games using unofficial opcodes
From: "Fred Quimby" <c9r@xxxxxxxxxxx>
Date: Wed, 1 Jun 2005 19:56:32 -0400
Emulator source code (Stella or Z26, not PCAE) will reveal most of what you 
need to know.  However, I have found that even these emulators don't do all 
of the exotic opcodes (in particular, neither seems to do RRA, which I tried 
to use in one of my games.)

Other than that, my source of info for my superoptimizer was these pages:

This page gives info on what each opcode does (but note that the mnemonics 
on this page are different from dasm's)

and this page had detailed info on a few weird opcodes and uses the same 
mnemonics as dasm.  Also it has some cycle-by-cycle information, including 
2-byte operations that take 8 cycles... might be useful for something.

>From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
>Reply-To: stella@xxxxxxxxxxxxxxxxxx
>To: stella@xxxxxxxxxxxxxxxxxx
>Subject: Re: [stella] Games using unofficial opcodes
>Date: Wed, 1 Jun 2005 13:23:01 -0400
>Hash: SHA1
>On Wed, 1 Jun 2005, Dennis Debro wrote:
> > I looked at this and I think it uses one by accident. It does a jmp to
> > LF01F which would cause the sax (opcode $83) instruction to be called.
> > They could have jmp'd to LF021 (which is the Veritcal Sync routine) 
> > would have bypassed this and the game would have worked the same.
>Is there a good complete opcode reference that includes all the 
>pro: discusses undocumented opcodes
>con: difficult to search, doesn't list status flags affected succinctly
>pro: hyperlinks for easy navigation
>con: no undocumented opcodes, doesn't list status flags affected succinctly
>pro: lists alternate names for undocumented opcodes
>con: doesn't list status flags affected succinctly
>pro: big chart has lots of information
>con: difficult to read, doesn't list status flags succinctly
>pro: nice charts, status flags affected are listed
>con: descriptions are terse, unclear which opcodes are not available on 
>pro: nice charts, nice explanation of how opcodes are decoded
>con: few english descriptions
>Is there a web page somewhere that combines the best of all these?
>One geared for atari 2600 programmers?
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