What are flag manipulation instructions in 8086?
Flag Manipulation and Processor Control Instructions
| Instruction | Description |
|---|---|
| CLC | Clear Carry Flag: This instruction resets the carry flag CF to 0. |
| CLD | Clear Direction Flag: This instruction resets the direction flag DF to 0. |
| CLI | Clear Interrupt Flag: This instruction resets the interrupt flag IF to 0. |
What are flag manipulation instructions give examples?
Instructions to transfer flag registers LAHF − Used to load AH with the low byte of the flag register. SAHF − Used to store AH register to low byte of the flag register. PUSHF − Used to copy the flag register at the top of the stack. POPF − Used to copy a word at the top of the stack to the flag register.
What is Flag instruction?
Arithmetic and Logic Instructions. Most Arithmetic and Logic Instructions affect the processor status register (or Flags) As you may see there are 16 bits in this register, each bit is called a flag and can take a value of 1 or 0. Carry Flag (CF) – this flag is set to 1 when there is an unsigned overflow.
Which flag is used by string manipulation instructions?
CMPS flag
What are the string manipulation instructions?
String is s series of data byte or word available in memory at consecutive locations. It is either referred as byte string or word string. Their memory is always allocated in a sequential order. Instructions used to manipulate strings are called string manipulation instructions.
How do you set a zero flag?
Zero Flag (Z) – After any arithmetical or logical operation if the result is 0 (00)H, the zero flag becomes set i.e. 1, otherwise it becomes reset i.e. 0. 00H zero flag is 1. MOV B 39 (load 39H in register B)
Which flag get set when the result is zero?
Zero flag (ZF) – the zero flag is set(1) when the result of an arithmetic operation is zero. Sign flag (SF) – the sign flag is set(1) when the result of an arithmetic operation has a 1 in the most significant bit (msb).
What is auxiliary carry flag?
Auxiliary Carry Flag (AF) is one of the six status flags in the 8086 microprocessor. This flag is used in BCD (Binary-coded Decimal) operations. This flag is set to one if there is a CARRY from the lower nibble or BORROW for the lower nibble in binary representation. Else it is set to zero.
How do I find my Auxiliary carry?
Auxiliary carry flag (Ac): Now let us consider the addition of any two 8-bit (2-hex digit) numbers, a carry may be generated when we add the LS hex digits of the two numbers….And they are:
- Carry flag (Cy),
- Auxiliary carry flag (AC),
- Sign flag (S),
- Parity flag (P), and.
- Zero flag (Z).