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) http://www.ffd2.com/fridge/docs/6502-NMOS.extra.opcodes 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. ftp://ftp.funet.fi/pub/cbm/documents/chipdata/64doc >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 > >-----BEGIN PGP SIGNED MESSAGE----- >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) >which > > would have bypassed this and the game would have worked the same. > >Is there a good complete opcode reference that includes all the >undocumented >instructions? > >http://www.s-direktnet.de/homepages/k_nadj/opcodes.html >pro: discusses undocumented opcodes >con: difficult to search, doesn't list status flags affected succinctly > >http://www.6502.org/tutorials/6502opcodes.html >pro: hyperlinks for easy navigation >con: no undocumented opcodes, doesn't list status flags affected succinctly > >http://members.chello.nl/taf.offenga/illopc31.txt >pro: lists alternate names for undocumented opcodes >con: doesn't list status flags affected succinctly > >http://www.xmission.com/~trevin/atari/6502_opcodes.html >pro: big chart has lots of information >con: difficult to read, doesn't list status flags succinctly > >http://www.oxyron.de/html/opcodes02.html >pro: nice charts, status flags affected are listed >con: descriptions are terse, unclear which opcodes are not available on >6502 > >http://axis.llx.com/~nparker/a2/opcodes.html >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? > >- -- >adam@xxxxxxxxxxxxxxxx http://cuddlepuddle.org/~adam >KG6GZR http://cuddlepuddle.org/~adam/resume.html > > >-----BEGIN PGP SIGNATURE----- >Version: GnuPG v1.2.1 (GNU/Linux) > >iD8DBQFCne7UyvXf5Z0z5zERAn09AKDNEOEPW9LaG8ZQDfO8JjmtRzObLACfQaOf >+k/6JWY7e7QY1ZdRyBgs3aM= >=QcmB >-----END PGP SIGNATURE----- > >Archives (includes files) at http://www.biglist.com/lists/stella/archives/ >Unsub & more at http://stella.biglist.com > Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
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