Preferred OpCodes

trisman · Post by **trisman** » Sun May 11, 2008 2:42 pm

Hey, I'm writing an assembler/linker/dis set of programs that targets among other things the nes. What are the preferred opcodes for mnemonics that there are many possibilities for like nop?

Thanks

Nessie · Post by **Nessie** » Sun May 11, 2008 2:56 pm

$EA is the official NOP, the other NOPs are not documented.

trisman · Post by **trisman** » Sun May 11, 2008 3:44 pm

Gratci.

blargg · Post by **blargg** » Sun May 11, 2008 5:12 pm

The other NOPs aren't official. They are documented, often called DOP (2-byte) and TOP (3-byte). See one of the documents about unofficial instructions (often erroneously called undocumented or illegal instructions). I don't think there's much opinion about how they are disassembled for NES, since they are rarely used by anything.