Yes, that will be difficult with your kernel, particularly as you probably have to reposition both P0 and P1? This technique is used in the 24 character text routines, but the distance for repositioning is fixed. Is the sprite position for the fruit always the same? It might be possible to draw the fruit using a single sprite by hitting RESP0 mid line? In any case, your kernel looks very nice!
Thanks. The fruit/key/pill position does change between zones. Right now I'm doing all the repositioning in the 2-line gap between fruits.
The problem with firing RESP0 midline is that in about half the cases it's fruits + something else (keys, power pills, super pills), and I don't think there's enough time to both switch graphics and reposition. The super-pill line, for example, takes 72 cycles to do this:
1. Load fruit graphic/color into P0
2. Load pill graphic/color into P1
3. Load pill graphic/color into P0 (now that the P0 fruit has been written)
4. Set left vertical door color (on or off) in PF
4. Set right vertical door color (on or off) in PF
5. Restore normal maze color in PF
6. Load fruit graphic/color into P1
7. Increment/loop to step 1
Squeezing anything else in there will be tricky.
I may have to resign myself to making this an emulator-only game if non-interlaced 30Hz won't look decent on real hardware. Finding enough cycles to interlace might be beyond my programming capabilities. :/