VECTORLIST - The Mailing List For The Technical Discussion of Vector-Based Arcade Games

October_1999
RE: vector programming...


From: Clay Cowgill ( )
Date: Mon Oct 04 1999 - 18:21:38 CDT


> Hmmmm... had to comment on this line of code. Looks like Atari didn't
> respect the stack page as being holy. Maybe they figured that $0180-01FF
> was good enough to the stack. In pouring through the Tempest code, I see
> numerous game variables that are stored between $0100-0180.
>
Hee-hee... Just saw this. Yeah, that "reserved for stack" is really more
like one of those yellow "warning" signs on a curve, people can and do
exceed it if you're careful and know what the code really does... ;-)

When you want to annoy hackers trying to follow your code doing indirect
writes to the stack and then RTS'ing out into new routines is pretty
entertaining...

Actually, I think the IRQ in Tempest has something of an un-intentional
recursion catcher built-in. Look for some funky-ness with a HALT
instruction a few lines into it.

-Clay


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