Re: R6502AP

From: Anders Carlsson <*anders.carlsson_at_sfks.se*> Date: Thu, 27 Nov 2014 10:56:41 +0100 Message-ID: <F6B1FD913BC54A5EB6D82D9273B062C7@ryds> · anders.carlsson_at_sfks.se

Groepaz wrote:

>> 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

See also this page discussing the 6502 decimal mode, which mentions that the 
2A03 handles setting and clearing the decimal flag, but doesn't implement 
the decimal mode. This is achieved by removing five transistors in the core.

http://visual6502.org/wiki/index.php?title=6502DecimalMode

Best regards

Anders Carlsson

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