The name and function of the flag of register F of 8086/8088

Cf -- carry flag ). If cf = 1, carry or borrow digits are generated during arithmetic operations. Otherwise, cf = 0. The shift instruction affects cf.

PF -- parity flag (parity flag ). If pF = 1, the number of "1" in the operation result is an even number. Otherwise, pF = 0. This flag is mainly used to check errors during data transmission.

Af-secondary carry flag (Auxiliary carry flag ). If AF = 1, the byte operation generates carry or borrow bits for the lower half-byte to the higher half-byte. Otherwise, AF = 0. The secondary carry is also called the half carry mark, which is mainly used for decimal adjustment of BCD code operations.

ZF -- zero flag ). If ZF = 1, the operation result is all zero; otherwise, ZF = 0.

SF -- sign flag ). If Sf = 1, it indicates that the result after the symbol number operation is a negative number; otherwise, Sf = 0.

Of -- overflow flag ). If of = 1, The result exceeds the maximum value when performing an arithmetic operation. Otherwise, of = 0.

If -- interrupt enable flag ). If if = 1, the CPU can respond to external requests that can block the interrupt. If if = 0, the CPU cannot respond to the interrupt request. The IF status can be set by the interrupt command.

DF -- Direction Flag ). If df = 1, the string operation is performed from the high address to the low address. Otherwise, df = 0. DF bit can be controlled by commands.

TF-trace flag ). It is also called a tracking flag. This flag can directly control the CPU running status during program debugging. When TF = 1 is a single-step operation, each time the CPU executes a command, it enters the internal one-step Interrupt Processing to check the execution of the command; If TF = 0, the CPU continues to execute the program.