On Thursday 27 November 2014, 10:53:56 Marko Mäkelä <firstname.lastname@example.org> wrote: > On Thu, Nov 27, 2014 at 09:11:27AM +0100, Gerrit Heitsch wrote: > >So far my impression was that all NMOS-6502 behave the same, including > >the ones from UMC (I have a 1581 with a UM6502A somewhere). The > >differences started with the CMOS variants. > > I read somewhere that Nintendo used an unauthorized copy of the 6502, > where the BCD mode was intentionally disabled in order to avoid > violating the patent that Chuck Peddle got for it. > > I wonder how that was done. Is the D flag still working, but just being > ignored? Does anyone have a NES? Were undocumented opcodes used in any > NES games? iirc the flag is ignored... and there are illegal opcodes, but they dont exactly match the known ones -> http://en.wikipedia.org/wiki/2A03 -- http://www.hitmen-console.org http://magicdisk.untergrund.net http://www.pokefinder.org http://ar.pokefinder.org boah im ganzen scheiss Internet is nix los, ich such mir bald Freunde wenn das so weitergeht! Message was sent through the cbm-hackers mailing listReceived on 2014-11-27 10:00:03
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