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Originally Posted by ImmortalA1000
I was searching for something I would assume was going to be an easy result to get out of Google but turns out there really isn't a thread on it anywhere I could find. I searched for extra half brite on here too as a title only search and got nothing.
I know you are manipulating 6 bitplanes and so it would be 1/5 additional CPU time or chipset time to finish graphic operations but I am reasonably certain that was not the only drawback of using EHB to try and do a 50fps scrolling game engine with blits all over the place (like an EHB version of SF2 would require).
Does anybody know of a site that goes into technical details about this sort of issue?
(I should probably search for that EHB arcade style game Bullfrog released but then again Bullfrog were no Shaun Southern/Adrian Edmonson class of Amiga 68k hardware bashing coders).
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It depends on how the Amiga architecture works.
To put it simply (it is more complex than that, but it is to give a general idea): with 6 bitplanes the processor access to shared memory (chip ram) occurs at half speed compared to when there are 4 bitplanes.
Furthermore, also the blitter has fewer cycles available to move more data.
And unlike the double playfield mode, which uses also 6 bitplanes, much more data need masking because there is no separation in the color table.
So yes, half-brite mode is very slow.