Subject: Re: [stella] zero page 6-digit routine From: Erik Mooney <emooney@xxxxxxxxxxxxxxxx> Date: Thu, 26 Mar 1998 15:18:19 -0500 (EST) |
> 57 bytes out of 128? :) I've never written a full game > for the A2600, but I'm sure that some games could get > by with the remaining 71... a few bytes could be saved > by saving the stack pointer externally to the routine, > I think... and normally 12 bytes are taken up by the > zero page pointers - that's integrated into the self > modifying code, so we're left with "only" 45 bytes > above a regular 6 digit display. > > Maybe some of the extra cycles could support some extra > jumps back into and out of ROM, for the non-selfmod > code, so we'd save RAM space, and still have a net gain > in cycles free? I'll have to try that, and get this > thing moving left and right :) That might actually work, though I really doubt you could gain enough cycles to make it worthwhile. You had 10 more than the ROM routine, right? JMPing to a different page takes four cycles if I remember correctly, so if you do one of those each way, you gain a whopping two cycles at a cost of still around 25 bytes of RAM. Let's not spend forever reinventing the wheel... there's a reason the original programmers used the routines they did. If we could improve on the wheel, letting it roll left and right (let me know when I carry this analogy too far :) ) it would be worthwhile, but I can already come up with plenty of ways to waste RAM :) It might well be worthwhile as/for a Supercharger-only game, though... saving those 10 cycles at a cost of zero bytes of RAM might help something. -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/stella.html Don't post pirate BINs to Stellalist. Be a programmer, not a pirate. Write the best game, win framed autographs of famous Atari alumni!!
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