* ADC is the only command for addition. To perform an addition without carry, the carry flag must be cleared manually first. Same with SBC for subtract.
* The TXS instruction does not affect any flag, while all other transfer instructions do.
* The BIT instruction copies bit 6 of the memory location to VF, regardless of any arithmetic overflow concept.
* The CLV (Clear Overflow Flag) instruction exist but not the SEV (Set Overflow Flag) instruction.
* On NMOS, INC A and DEC A instructions do not exist. They do exist on CMOS.