Date   : Tue, 05 Sep 2000 15:00:23 -0700 (PDT)
From   : Thomas Harte <t.harte@...>
Subject: Re: FRAK!

On Tue, 05 Sep 2000 09:42:02 +0100, Joel Rowbottom wrote:

>  > Zalaga's sprite routines were written almost solely with undocumented
6502
>  > opcodes which just happened to do the right things
>  
>  Ah yes, I think that's why it seemed to hate the Rockwell 6502 and any
attempt to
>  run it on an Electron ;)

There is an Electron version of Zalaga which seems to run fine on my
Electron emulator, and I've not really done any undocumented opcodes on that
at all. The sprites move really horribly though.

So, does the Rockwell not do the unofficial opcodes? The only documentation
I have seen claims that the only way not to get the unofficial opcodes is to
switch NMOS to CMOS (or the other way, I forget), which also changes which
instructions do care about low byte to high byte carry, and therefore is not
what Acorn have done.

So, what exactly is the deal with the Rockwell & the unofficial ops?

-Thomas





_______________________________________________________
Say Bye to Slow Internet!
http://www.home.com/xinbox/signup.html