Thread: Amiga Vs ST
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Old 11 September 2014, 18:07   #477
mc6809e
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Join Date: Jan 2012
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Quote:
Originally Posted by Cyprian View Post
interesting point.
do you know how many blitter registers CPU have to write to do such a operation and how many cycles it eats?
Am I right that, you have to repeat that blitter init operation for each bitplane?
Bitplane rasters can be interleaved on the Amiga. Bitplane one's first raster is followed by bitplane two's raster is followed by bitplane three's first raster, etc.

This mean that when blitting to a standard 16 color display, you can treat the screen as a single 320x800 bitmap and blit once.

Not sure how many cycles it eats, but in some cases those cycles are free since the the blitter is capable of accessing memory every two CPU cycles while the CPU is only fast enough to access memory every four CPU cycles. This means that DMA cycles that would be wasted on other platforms (like the ST) can be used by the blitter on the Amiga.
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