Hi Kurt,
> Does anyone know more about that display list? Which things can
>the ANTIC change in each scanline without CPU interaction?
OK ANTIC *IS* a CPU, albeit one with a very simple instruction set,
dedicated to generating the display (with help from C/GTIA). The display
list is the program which tells ANTIC how to generate the display.
AFAIR, without intervention from the 6502, all ANTIC can change on a
scanline by scanline basis is the display mode.
>....Does anyone know recourses on the Internet about that? I'd like
>to learn more about it...
Have a rummage around some of the Atari sites which search engines like
"Lycos" throw up. Look for a copy of "De Re Atari" or one of the many
programmer's guides floating around.
> Well...as far as I know, the Atari ST didn't have that text mode either.
Correct, all three screen modes are bitmapped.
>....There were many smooth scrolling C-64 games....
>....I don't know how this worked on the Ataris....
You simply enabled horizontal and/or vertical fine scrolling on a line by
line basis in the display list - meaning only those lines you wanted to
scroll would be scrolled and only in the planes you specify - and then wrote
the appropriate values into HSCROL and/or VSCROL.
Once you've reached the maximum fine scroll value (depends on display mode)
you update the LMS instructions in the display list (these tell ANTIC from
where in RAM to fetch display data) so that data is fetched from a new part
of RAM, your "hard scroll"....this means you don't have to shift any of your
screen data around.
TTFN - Pete.
--
Hardware & Software Engineer. Sound Engineer.
Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC)
peter.pachla@xxxxxxxxxxxxxxxxx | www.wintermute.org.uk
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