People often seem to confuse 16-bit colour with images that are generated by a 16-bit processor. They're not the same.
The NES had an 8-bit processor, but it only had 6-bit (64) colours. DOS also had 6-bit (64) colours, I believe. The SNES had 15-bit colour.
The NES had an 8-bit processor, but it only had 6-bit (64) colours. DOS also had 6-bit (64) colours, I believe. The SNES had 15-bit colour.