Date   : Wed, 10 Jan 1996 18:20:27 GMT
From   : Nigel Barrett <nigel@...>
Subject: Re: Illegal opcodes

In message <7C43A4F0755@...> you wrote:

> (I meant to put this in my e-mail yesterday but I forgot.)
> 
> At home I have an old Acorn User (I can't remember which issue) which 
> has a listing of all the 6502 illegal opcodes. Apparently they are 
> valid for 6502s marked 'SY6502A', and there is a small test program 
> to test if your 6502 implements the more useful ones. The 
> descriptions are also more helpful than 6502.txt (instead of LAX this 
> listing gives LDA-LDX for example) although it isn't as complete. 
> There are also no cycle timings, although these would be easy enough 
> to find out.
> 
> Is anyone interested? If people are I'll scan it in as a bitmap (the 
> page is black on yellow so it should come out OK) next time I'm at 
> home (end of January I should think) and e-mail it to people.

The illegal opcodes are probably manufacturer-dependent. I remember the 
CPU in the 6502 2nd processor had a different set.


Nigel

-- 
"Do something, Gromit!"                          Nigel Barrett
                - AClose Shave                  nigel@...