Hold
And
Modify (HAM) is a graphics mode on the
Amiga computer which allows you to get more
colors from the
hardware by using two
bits from each
pixel to control a "hold" and "modify"
feature of the base
colors. 6-bit HAM (
HAM6) used 4 bits for base colors, while 8-bit HAM (
HAM8) used 6.
The HAM feature was hacked by Jay Miner, who almost removed from the early model Amiga architecture due to it's slowness. It is fortunate to have survived since it was one of the first graphic modes on a personal computer to show photorealistic images.
It would be awesome if someone could write a really detailed description of how HAM works.