Originally Posted by Shawn68z

If I wrote my microcontroller in this fashion I would have been fired. The bit addressing you are describing is used in hardware design to address external chips, not the way you would use the memory inside the microcontroller. Space is limited in a microcontroller, but by using 1 byte of ram you could have upto 255 steps if you wish.
Most likely 64 is just easier for the math calculations, where 100 percent is a pain in the butt when the microcontroller doesnt have an FPU. (Multiplication and division are clock intensive operations. )

In the worse case scenerio, HW has used look up tables for each of the step values, that would be a major memory hog.

Cheers,
Shawn.