Glenn Saunders wrote:
> At 11:11 AM 11/10/2001 +0100, you wrote:
>>...you could reduce the vertical resolution (not the positioning!) to two
>>pixels. Then you would need four (2x2) kernels, depending if your missiles
>>start at an odd or even line. That way you could reduce the missile
>>cycles down to 52, plus a few extra cycles (~6..10) because you have to
>>clear the HMMx registers.
> If you aren't going to reduce the vertical positioning then how do you get
> both missiles to start on the same scanline?
As I said, you need four kernels:
1. both missiles start in the first row
2. missile 0 starts in first row, missile 1 in second row
3. missile 0 starts in second row, missile 1 in first row
4. both missiles start in the second row
> I think the problem with your math is that you aren't taking into account
> the timing-critical playfield code. The two little windows of time between
> the playfield load/stores are very short. I'll experiment a little and see
> if I can wedge the sprite code in there. I don't know what else I could
> use that area for. Right now each area is only 16 cycles long.
Well, you can reorganize your playfield writes:
LDA <PF1DataRAM-1,X ; 4
STA PF1 ; 3 @27 (just in time :-)
LDA <PF2DataRAM-1,X ; 4
STA PF2 ; 3 @34
LDA <PF1bDataRAM-1,X ; 4
STA PF1 ; 3 @41
LDA <PF2bDataRAM-1,X ; 4
STA PF2 ; 3 @48
That way you can move the cycles before the PF writes and merge them
with other cycles.
Have fun!
Thomas
_______________________________________________________
Thomas Jentzsch | *** Every bit is sacred ! ***
tjentzsch at web dot de |
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