====== Sinclair QL - Displaying Bitmaps & Text ======

Direct video memory

Video memory starts at 0x20000

In Mode 4 (512x256 4 colour) the memory is laid out in byte pairs (or words)

<code>
Red byte        | Green byte
0 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0
</code>

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

<code>
Red | Green | Result
1   | 0     | Red
0   | 1     | Green
1   | 1     | White
0   | 0     | Black
</code>

Example 1:
<code>
0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
</code>

...would draw an 8 pixel horizontal line in //Green//.

Example 2:
<code>
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
</code>

...would draw an 8 pixel horizontal line in //White//.

Example 3:
<code>
1 0 1 0 1 0 1 0 0 1 0 1 0 1 0 1
</code>

...would draw 8 alternating pixels of //Red// and //Green//.