potter@speedway.DAB.GE.COM (Jeff Potter) (02/08/91)
Hi Jesper!
Your HiRes+8 color program is similar to my COLRVIEW system. I typed
in your program (after correcting the mistakes in your posting), and
it appears you page-flip between a red, green, and a blue screen.
This has a real annoying flashing effect on my system. I considered
doing this about a year ago to get 4096 colors out of graphics 9.
Then I invented COLRVIEW, a program to view three graphics 9 picture
files. Instead of displaying a whole screen in one color, I alternate
colors on adjacent lines. Then I page-flip to three different screens:
Screen 1 Screen 2 Screen 3
RRRRRRRR GGGGGGGG BBBBBBBB
GGGGGGGG BBBBBBBB RRRRRRRR
BBBBBBBB RRRRRRRR GGGGGGGG
RRRRRRRR GGGGGGGG BBBBBBBB
etc. etc. etc.
The three screens contain unique information, and thus take nearly
24k of screen RAM. A display list interrupt changes the color of
every line, and a VBI sets the screen number by changing the display list.
It sounds awkward, but I got it to work.
The results are more pleasing than mere page flipping. A less annoying
vertical "washing" effect occurs, rather than harsh flashing.
I wrote a GIF viewer (APACVIEW) for the 8-bit that can decode to this mode
(alas, it can't also display in that mode, as there is not enough RAM to
support both GIF decoding and the 24k of screen RAM). My COLRVIEW program
will then display pictures created with APACVIEW. Both programs work in
either graphics 9 (4096 colors, 80H x 192V) or graphics 15 (64 colors,
160H x 192V). I also wrote a Degas (Atari ST) viewer for the Atari 8-bit
which decodes and displays directly in this mode. It is called DEGASRD.
Send me email if you are interested in these programs, or more details on
how it all is programmed. The results of some of these decoded images is
fantastic (IMHO). These are all available on GEnie and CompuServe. Some
time ago, I think somebody may have posted UUEncoded versions of one or
more of these. If you simply cannot find them, I can mail to you direct.
--
Jeff Potter
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