pthiesse@jarthur.Claremont.EDU (Paul Thiessen) (02/01/89)
Hello. Can anyone out there tell me how to program the palette on a
Paradise VGA Plus card? It's capable of 262144 colors (15 at a time, of
course), and I'm sick of the 15 colors the IBM uses by default. I'd love to
have, say, 15 shades of red. I have a good knowledge of assembly and DOS/BIOS
programming.
Also, how do I go about writing directly into the video memory, instead of
having to use the (relatively) slow BIOS putpixel routine? I know where the
memory is, but when I write to it, I can only get black and white.
Thanks for any help. If you don't want to post any info on the network,
e-mail to me at pthiessen@hmcvax.bitnet or pthiesse@jarthur.claremont.edu
Thanks again,
Paul Thiessenannala@neuro.usc.edu (A J Annala) (02/02/89)
I thought the CGA adaptor was capable of 256 simultaneous colors ... or is that another IBM PC adaptor? In any case, can someone fill me in on the capabilities of the 256 color IBM PC adaptor? Can it generate 256 grey scales ... 256 independently controlled colors ... or is it simply confined to whatever existing palette it comes with. Thanks, AJ .
toma@tekgvs.LABS.TEK.COM (Tom Almy) (02/02/89)
In article <109@jarthur.Claremont.EDU> pthiesse@jarthur.Claremont.EDU (Paul Thiessen) writes: > Hello. Can anyone out there tell me how to program the palette on a >Paradise VGA Plus card? [...] > Also, how do I go about writing directly into the video memory, instead of >having to use the (relatively) slow BIOS putpixel routine? [...] There is one book that tells all for the VGA, EGA, CGA, and various Hercules cards: Programmers Guide to PC & PC/2 Video Systems Richard Wilton Microsoft Press I don't care for the format of the book (it discusses all cards in parallel), but I sure like the contents -- it has saved me more times than you can imagine. Tom Almy toma@tekgvs.labs.tek.com (new address) Standard Disclaimers Apply
mfinegan@uceng.UC.EDU (michael k finegan) (02/03/89)
In article <15102@oberon.USC.EDU>, annala@neuro.usc.edu (A J Annala) writes: > I thought the CGA adaptor was capable of 256 simultaneous colors ... or VGA > Can it generate 256 grey scales ... 256 independently controlled colors ... While 256 colors are available in 320 x 200 (columns x rows) mode, the IBM VGA uses 6 bit DAC's, so it is impossible to get more than 64 grey shades, since grey implies R = G = B, leaving 0 to 2^6 - 1 as possible unique LUT locations ... An excellent reference (complete w/ source code to program palette's, etc., etc.) is : Programmer's Guide to PC & PS/2 VIDEO SYSTEMS by Richard Wilton (Microsoft Press). I had to use a current ROM BIOS reference (Ray Duncan -- also Microsoft Press) for the VGA palette save/load routines, but it was fast enough for what I wanted ... Hope this helps, Mike Finegan mfinegan@uceng.uc.edu
naughton%wind@Sun.COM (Patrick Naughton) (02/03/89)
In article <15102@oberon.USC.EDU> annala@neuro.usc.edu (A J Annala) writes: >I thought the CGA adaptor was capable of 256 simultaneous colors ... or >is that another IBM PC adaptor? In any case, can someone fill me in on >the capabilities of the 256 color IBM PC adaptor? Can it generate 256 >grey scales ... 256 independently controlled colors ... or is it simply >confined to whatever existing palette it comes with. CGA must have been a typo (or a joke). The CGA can only display four colors in a 320x200 pixel mode. (There are four different sets of four ugly colors to choose from) The VGA displays 256 colors from a palette of 262144 colors. You can control which of the 256 colors are displayed by setting the palette with the 256 R, G, B triples you want. The major restriction of this is that IBM wanted to save money on parts so they used 6 bit DACs rather than 8 bit DACs. So each channel can only have 64 levels, (1<<6), thus you cannot have 256 grey scales, or 256 blue scales, only 64. One good thing is that most VGAs on the market today will drive MultiSync monitors to 800x600 and 1024x768 pixels, although the IBM standard only specs 640x480 as the highest resolution. -Patrick ______________________________________________________________________ Patrick J. Naughton ARPA: naughton@Sun.COM Window Systems Group UUCP: ...!sun!naughton Sun Microsystems, Inc. AT&T: (415) 336 - 1080
silver@eniac.seas.upenn.edu (Andy Silverman) (02/03/89)
I think the original author was confusing CGA and MCGA. MCGA is an enhancement to the original CGA spec which is used only in the PS/2 models 25 and 30. The MCGA includes an extra video mode which allows 320x200x256. Andy Silverman Internet: silver@eniac.seas.upenn.edu CompuServe: 72261,531