On Wed, 21 May 2008 15:29:28 +0100, "Colin Piggot" <[EMAIL PROTECTED]> wrote: > Andrew Collier wrote: >> If I used IM1 this would require that either, a) the screen goes in > sections A >> and B, and the interrupt routine is actuially visible in pixels - or b) > the >> moveable window goes in sections A and B, and I have to duplicate the >> interrupt routine in nearly every page of memory. > > That's the approach I was taking years ago for Chrome, I'd have a couple K > dedicated to the main core of the code and interrupt routines at the start > of many 32K chunks of code and sprite data, so AB pages could be shifted > around keeping the screen in CD - with the 8K above the screen holding > other data.
You'd only need 3 bytes in each page to jump to 57344 (or 57400, maybe). So that's 96 bytes taken rather than 256, although they're spread out through memory which could cause problems... You're right, though, Andrew - your example hadn't occurred to me. I did say I was happy to be wrong :) Geoff
