Date   : Thu, 04 Jan 1996 19:22:36 GMT
From   : Angus Duggan <angus@...>
Subject: Timings for 65c[01]2 NOP instructions

James Fidell writes:
>I'm putting 65c02 and 65c12 support into my Beeb emulator and I'd like to
>clarify a few things about the NOP instructions, which I can't find
>documented anywhere.
>
>Firstly, are all the NOPs single byte instructions ?  I'm assuming that
>they aren't and that they retain the same addressing mode that their
>positions in the tables of op-codes would imply.

There is only one "official" NOP for the 65c02, which is &EA, and is one byte.
The spare instructions are quite free to do different things for each
manufacturer's implementation of the processor (and did differ between the
Rockwell and Motorola 6502 implementations).

a.