Sinclair QL - Displaying Bitmaps & Text

Direct video memory

Video memory starts at 0x20000

In Mode 4 (512×256 4 colour) the memory is laid out in byte pairs (or words)

//Red// byte    | //Green// byte
7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0

Those 16 bits set a series of 8 pixels. The values of the Red and Green byte are AND-ed to get the final colour:

Red | Green | Result
1   | 0     | Red
0   | 1     | Green
1   | 1     | White
0   | 0     | Black