On 21 Feb 2009, at 21:38, Simon Cooke wrote:
Hey guys…
I was wondering… does anyone have a fully-detailed breakdown of
instruction timings for the SAM? Including at various points in the
screen?
I’m tempted to write a code-generator to render bitmaps in more than
the 16 colors available, using a genetic algorithm (or even a monte
carlo sim) to get as close as possible. The idea is that it’d
generate code to change the palette as the screen renders, and
adjust the bitmap to get the closest it could to the original
source. Kind of a little like hold-and-modify mode on the Amiga, but
done the hard way.
This is, of course, just a curiosity at this point… but I’d be
interested in seeing if anyone had any ideas…
There's a rather detailed list of instructions in issue 2 of Based On
An Idea... surely you would have subscribed to that magazine? ;)
I think the only question it doesn't answer is what happens to the 112
t-state difference between the number of t-states measured with the
screen off (119696) and the number that would be expected from the
timing characteristics of the screen display (119808). Perhaps the
SimCoupe source would show how those are accounted for? (because if it
doesn't, any code that depends on the difference would work improperly
on either SimCoupe or hardware Sams...) That said, I don't remember
noticing any differences between one horizontal line and any other
horizontal line, (that is, I coded a number of effects which used OUT
timings at specific horizontal points of the screen - ETunes player
from Fred 63, for example - and I didn't have to vary the delays when
the effect was moved between different vertical co-ordinates) so I
would guess the effect is contained within the top or bottom border
near the frame interrupt, and is unlikely to inflict any significant
disruption.
Another rather interesting prospect would be that you might be able to
literally improve the graphics by plugging in a mayhem accelerator...
Andrew
--
--- Andrew Collier ----
---- http://www.intensity.org.uk/ ---
--
