🚀 go-pugleaf

	I still don't seem to have the hang of video modes.
	By my recollection, there are 8 pixels/byte in EGA mode,
and to get a color, you add the bits from each plane to get the
color (plane 3 seems to be the high value, so for value/color
1010, or 9 decimal, it's stored in say bit 7 of plane 3 as 1,
2 as 0, 1 as 1 and plane 0 as 0).
	Also, i thought that mode $13 used only one plane which is
why it could only access 64k. Also, the mode is linear (all 8 bits
are always in the same plane).
	But according to Ferraro (pg 147):
	"Mode 13 hex uses all four bit planes...The four planes are
chained so that sequential bytes in host memory are loaded into 
alternating bit planes."
	So does that mean that mode $13 is planar, but color bits
aren't split between planes? If that is the case, why only 64k?
I guess if you had 6 colors, 0, 5, 15, 6, 8, 16, they would be stored
with color 0 and 8 in plane 3, 5 and 16 in plane 2, etc.
	Also, how is Mode X,Y,Z,etc laid out? I would think they're
like EGA and have 2 bits per pixel, with the bits making a color
spread over several planes. But in staring at the linear_to_pbm
functions in my excellent Egg archives, all the function seems to
do is take every fourth pixel/byte and place them next to each other,
repeated at the end for each plane. That means all 8 bits for a color
are in the same plane, like they say mode $13 is, but completely
unlike EGA modes.
	I still don't understand using color planes, and i hope to 
fairly soon do both a demo game in both EGA and Mode X, and thought
that knowing planes for one obviously moved over.
	And what is this Chain 4 thing I've heard of? I have all
Abrashes code from ftp, but never got the text of the article.
	Can anyone help? I have lots of vga source code (no ega
code unfortunately), but very little understanding as to how they 
work.
	Thanks	
							- baylor


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baylor@emx.utexas.edu   "There is no such thing as an innocent Kennedy"
I'm to sexy for $4.69 an hour...
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