The SUB instruction subtracts the "B" register from the "A" register, and stores the result to a register, counter, or location in memory. This is a twos compliment subtraction, so it includes an additional minus 1. For the latter, the address pointer must be setup before the SUB writes to memory.

460A - Store the result to the "A" register.
460B - Store the result to the "B" register.
460C - Store the result to the "C" general purpose register.
460F - Store the result to the "F" output high register.

4600 - Store the result to memory, at the current active address.
4601 - Store the result to address pointer 1.
4602 - Store the result to address pointer 2.