blitter speed and fmode

jotd · 19 June 2021, 10:26

if you have a game that blits using OCS FMODE = 0 and you have AGA is that possible to blit faster by changing FMODE? or is it unrelated?

mcgeezer · 19 June 2021, 11:22

Quote:

Originally Posted by jotd

if you have a game that blits using OCS FMODE = 0 and you have AGA is that possible to blit faster by changing FMODE? or is it unrelated?

It depends on what the game is doing. If it's a static screen game then you should be able to change to fetch x 4 and modify the display modulo and DDF start and stop values.

That would the blitter more slots and therefore would be faster.

a/b · 19 June 2021, 15:38

It's unrelated. Blitter is 16-bit, and you need proper alignment/size for double CAS and/or 32-bit which is something you can guarantee with sprites and bitplanes but not with the blitter.
It's only faster indirectly, by having more dma slots available for blitting.

19 June 2021, 10:26	#1
jotd This cat is no more Join Date: Dec 2004 Location: FRANCE Age: 51 Posts: 6,961	blitter speed and fmode if you have a game that blits using OCS FMODE = 0 and you have AGA is that possible to blit faster by changing FMODE? or is it unrelated?

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19 June 2021, 15:38	#3
a/b Registered User Join Date: Jun 2016 Location: europe Posts: 806	It's unrelated. Blitter is 16-bit, and you need proper alignment/size for double CAS and/or 32-bit which is something you can guarantee with sprites and bitplanes but not with the blitter. It's only faster indirectly, by having more dma slots available for blitting.

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