status register

A status register is a collection of flag bits for a microprocessor that indicates the status of various mathematical operations. These flags are commonly used during conditional testing and program branching. Different microprocessors have their own sets of status flags. Many times, these flags are unique to the microprocessor, due to specific device configurations, et cetera.

Common Status register flags

Z = Zero flag. The result of a mathematical operation is zero
C = Carry flag. The result of an operation has produced an answer greater than the number of available bits. (This flag may also be set before a mathematical operation to provide a "Borrow" bit)
N = Negative flag. The result of a mathematical operation is negative
V = Overflow flag. A register or memory location has overflowed its number of available bits. (Similar to the carry flag)
I = Interrupt flag. Interrupts can be enabled/disabled by setting or clearing this flag.

Status Register

Common Status register flags

See also