On Thursday, August 10, 2017 at 3:48:55 PM UTC-4, chitselb wrote:
> If you needed 141 bytes of zero page on a C-64, what addresses would
you use?  BASIC is switched out, Kernal is still switched in, so anything
BASIC uses can be reallocated.  Having it all be contiguous so I can go in
and out of BASIC is important too.
>
> On a PET (4.0 ROM) I'm just using $00-$8C (everything below jiffy
clock) and there's a little ML routine ('aloha') to swap the half page in
and out, but I want to port PETTIL to the C=64

On a C64, the BASIC ROM uses ZP addresses $02-$8F, but you can use kernal
ZP locations you don't need in your program.  For example, $83-$8B and
$AE-$B6 are used for tape and RS232 and $F7-$FF are for RS232 and free
space.  Does this help?

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