[comp.sys.atari.st] Color Confusion

MacDonald.pa@XEROX.COM (08/24/87)

I'm writing some MIDI controlled graphics in Forth.  I have rudimentary
access to A-line, VDI, AES and xbios.  I have read Internals and Gem
Programmers Reference but I do not understand how color actually works
in the ST.  

I would like to use the A-line commands but...

What does the term PLANE actually mean?  I can only figure that you use
4 32bit words to describe 4 bits.  
If you use Setpallette from xbios why does the example indicate 18 words
to describe 16 colors?  Are these other words commands?  The A-line
description of color/resolution says something about an inverse video
command in color palette register 0???
xbios talks about colors having values between $000 and $777 with 777
being white, VDI/AES talk about 1000 levels each of R,G, and B.  What's
the story here.

I would be happy to summarize responses to keep digest traffic down.

Thanks,
Dale.  

ARPA: <MacDonald.pa@Xerox.COM>