Quote:
Originally Posted by sandruzzo
16 colors for 1x1 would suffice. Why use 2x2?
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Because we are are using fast memory the DMA will have no effect on the speed of the CPU. It's more about what the 68000 running from fast can write into fast memory. A byte is still used for the chunky buffer so by cutting the colour depth down will not actually speed the writes up because you still process the same amount of data. And in the case of 1x1 pixels you x4 the amount of data to shovel around. An example of this is the copy to chip takes .5 frames to happen. So 2x1 pixels will take a frame and 1x1 pixels will take 2 frames... it would not be worth doing.
But saying all that it would be nice to detect CPU speed and adapt for better quality. But the whole purpose of this exercise is to get something that would work on a Amiga 1000 with fast memory at a nice frame rate.
Edit:
Also to note is the blitter time. In realistic terms the more data we need for the chunky buffer means the more the blitter has to convert. The hard limit on this is that over 3 frames the blitter can convert 2x1 pixels for 6 bit-planes. Using 1x1 pixels the blitter will not have enough time for the conversion.
The test I've been doing is just to see what bandwidth is available for the blitter as well as the 68000 running in fast. The reason why fast memory helps is because we can use parallel processing - the blitter and the 68000 can run in tandem with no DMA contentions.