pixel-modes.txt

# Memory Map

0000-7FFF - ROM / Video
8000-FFFF - RAM

# Video Memory
0000-779F - Video memory

??A0 - ??FF not visible on screen
7800 - 7FFF not visible on screen

0-159 (00-9F) x-coord
0-119 (00-77) y coord

# Pixel modes
8 bits per pixel

1. 64 colour mode
Sets a pixel to one of 64 colours
	00 rr gg bb
e.g. 00 11 11 00 = 3C - Yellow

2. 64 colour background	

Sets a background colour register on the VGA board to
one of 64 colours, as above
	01 rr gg bb
	
e.g. 01 00 11 11 = 4F - Cyan
	
3. Text mode
Sets a patern of 4 sub-pixels to either the forground colour
or the background colour set by the background colour register.
The forground colour is one of 8 colours and set in the 
pixel data.

	1 rgb ABCD
	
CD
AB

e.g Red diagonal: 
O is set, . is unset

 .O
 O.

1 100 1001 = C9
100 = Red (r=1, g=0, b=0)

e.g Yellow diagonal: (other way)

 O.
 .O
 
1 110 0110 = E6
110 = Yellow (r=1, g=1, b=0)

00110000 = red square
01110000 = red square (background)
11001111 = red square
1100???? = red square (if background = red)