Originally Posted by TroyWilkins
Ahh, ok, thank you, any idea what the correct number would be? That was the number I remember being used by everyone back in the day.
Technically HAM8 can access all 16,777,216 colours - though not in a way that's particularly useful.
In HAM8 mode every pixel can either select a base colour (in which case all eight bits per component of the base colour are used), or it can modify just the upper six bits of either the red, green or blue component. The lower two bits aren't touched, so they remain however the last base colour left them.
What this means is that once you've set a base colour, you can modify the upper 6 bits of each gun and access 262,144 colours in total. To access the colours in between you need to change the lowest two bits of each component, and you can only do that by selecting a different base colour. If you set the lower 2 bits of each component uniquely for all 64 colours in the base palette, it's possible for HAM8 mode to access any of the AGA chipset's 16,777,216 colours - but in practice this isn't particularly useful.