The flag register in the 8086 microprocessor is a 16-bit register that contains status and control flags. It has 9 flags that indicate the status of arithmetic or logical operations performed by the ALU. The 6 status flags are: the carry flag (CF), parity flag (PF), auxiliary carry flag (AF), zero flag (ZF), sign flag (SF), and overflow flag (OF). These flags provide information about the results of operations, such as whether there was a carry out, if the result was even or odd parity, or if the operation resulted in a zero value.

1. Flag Register in 8086
Microprocessor
Presented by
Khairnar sayali

2. What is a flag register in
8086 microprocessor?
 8086 has 16-bit flag dividing two parts:
 16-bit flag :- 1) 9 flag = i) status flag ii) control flag
2) 6 flag=unused
 Flag register is a 16-bit register, but there are only 9 flags avalaiable in the
8086 microprocessor.

3. Flag register of 8086

4. Types of flags of flag register in 8086
microprocessor
 flags:-There are two types of flags of flag register in 8086 microprocessor:
1) status flags 2) control flags
 Status flags
In the flag register, 6 out of 9 flags are used as status flags. When the microprocessor performs
an arithmetic or logical operation in ALU, then depending upon the status of the result, the
microprocessor will store corresponding status bits 0 or 1 in status flags. The status flags are,
 Carry flag (CF)
 Parity flag (PF)
 Auxiliary carry flag (AF)
 Zero flag (ZF)
 Sign flag (SF), and
 Overflow flag (OF).

5. CF:
It stands for carry flag.
If CF = 1 ; it means carry is generated from the MSB.
If CF = 0 ; no carry is generated out of MSB.
Example :
PF:
it stands for parity flag.
If PF =1 ; it means it is even parity in the result (there are even numbers of 1’s).
If PF =0; it means it is odd parity.
In example 1, there are 4 ones’ which is even , in the second example there are 5 ones’ which is odd in count.

6.  AF
AF stands for auxiliary flag. As 8-bits form a byte, similarly 4 bits form a nibble. So in 16 bit operations there are 4
nibbles.
If AF = 1 ; there is a carry out from lower nibble.
If AF = 0 ;no carry out of lower nibble.
ZF:
This is zero flag. Whenever the output is 0 this flag is 1.
If ZF = 1 ; output is zero.
If ZF = 0 ; output is non zero.
OF:
OF stands for overflow flag.
The are two types of numbers
1.Signed
2.Unsigned