Date   : Mon, 15 Jan 1996 20:18:29 GMT
From   : Nigel Barrett <nigel@...>
Subject: Re: Illegal opcodes

In message <Pine.SOL.3.91.960115045134.24761A-100000@...>
you wrote:

> 
> Has anyone figured out Orlando's code from the Zalaga loader - as far as I
> can tell the loader *code* jumps to the start of an ascii message which is
> an author credit/copyright message. (Most of the start compromises
> non-standard opcodes.) Presumably somewhere in this mess we jump to some
> more sensibly code, but it's difficult to tell. It also looks like there 
> might be a tune-player in there of sorts, but that's hard to tell also.
> 
I once had a BASIC disassembler which I modified to do all the illegal
opcodes. Don't ask me to find it, it's long gone, but a new one shouldn't
take you more than a few hours to knock out.

I had a cmos 65c02 in my beeb because the standard one used to overheat.
The _only_ program that was affected by this was Zalaga, which used to 
leave trails behind all the moving sprites. I assume he was using the 
illegal opcode to store zeros on the screen. Git.

Nigel

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