I know a lot about these chips and learned something new:
There is a single cycle NOP on the 65C02! Spiffy!
---Excerpt Below---
There aren't really any undocumented instructions on the 65C02--any instructions not listed above are documented as performing no operation.
However, these alternate NOPs are not created equal. Some have one- or two-byte operands (which they don't do anything with), and they take different amounts of time to execute.
Funny, because I was just using this yesterday to adapt my rust 6502 emulator to 65C02. It's not as useful as for the 6502 since the 65C02 instructions are much less regular, but I like that way of looking at the instruction set, I feel like it shows the underlying logic of the designers.
Programming in JavaScript feels like being adrift in a realm of pure thought. Programming in 6502, you can feel the electrons pulsing through the thin carpet beneath your feet.
As somebody who's been learning about 6502 internals recently, this web page has been incredibly helpful. It's not a silver bullet, there's a lot of instructions that don't fit the pattern, or they do fit the pattern and there's only one or two of them so there's little point, but for the most regular operations (Group 1: ORA, AND, EOR, ADC, STA, LDA, CMP, SBC) it makes things so much easier.
I know a lot about these chips and learned something new:
There is a single cycle NOP on the 65C02! Spiffy!
---Excerpt Below---
There aren't really any undocumented instructions on the 65C02--any instructions not listed above are documented as performing no operation.
However, these alternate NOPs are not created equal. Some have one- or two-byte operands (which they don't do anything with), and they take different amounts of time to execute.
Instruction Bytes Cycles