|-
| P (Processor Status) || 8-bit ||
* bit7 - NF - Negative Flag: 1 when result is negative* bit6 - VF - Overflow Flag: 1 on signed overflow* bit5 - Unused (: always set to 1)* bit4 - BF - Break CommandFlag: 1 when interrupt was caused by BRK* bit3 - DF - Decimal Mode Flag: 1 when CPU is in Decimal Mode* bit2 - IF - Interrupt Disable Flag: when 1, no interrupt will occur (except BRK and NMI)* bit1 - ZF - Zero Flag: 1 when all bits of a result are 0* bit0 - CF - Carry Flag: 1 on unsigned overflow
|| Flags are affected by most operations.
BF is not a physical flag implemented in a register. It only appears on the stack when the P register is pushed to it.