What is push and pop instruction?

What is push and pop instruction?

Instructions that store and retrieve an item on a stack. Push enters an item on the stack, and pop retrieves an item, moving the rest of the items in the stack up one level.

What is push instruction in 8086?

PUSH — Push Operand onto the Stack PUSH then places the operand on the new top of stack, which is pointed to by the stack pointer. The 80386 PUSH eSP instruction pushes the value of eSP as it existed before the instruction. This differs from the 8086, where PUSH SP pushes the new value (decremented by 2).

What is push ax?

These first instruction shall push the value stored in AX (16-bit register) to the stack. This is done by subtracting a value of 2 (2 bytes) from SP. The new value of SP becomes 0xF81E. The CPU then copies the value of AX to the memory word whose physical address is 0x1F81E.

How is push B instruction executed?

It is a 1-Byte instruction. The result of execution of this instruction is shown below with an example. Summary − So this instruction PUSH B requires 1-Byte, 3-Machine Cycles (Opcode Fetch, Memory Write, Memory Write) and 12 T-States for execution as shown in the timing diagram.

What does push a instruction do?

The push instruction places its operand onto the top of the hardware supported stack in memory. Specifically, push first decrements ESP by 4, then places its operand into the contents of the 32-bit location at address [ESP].

What is push and pop Instruction in 8051?

When the 8051 is initialized, the SP register contains the value 07H. This means that the RAM location 08 is the first location used for the stack. The storing operation of a CPU register in the stack is known as a PUSH, and getting the contents from the stack back into a CPU register is called a POP.

Is push ax a valid instruction?

4. Which of the following instruction is not valid? a) MOV AX, BX b) MOV DS, 5000H c) MOV AX, 5000H d) PUSH AX Answer: b Explanation: both the source and destination operands cannot be memory locations except for string instructions.

What will not be in the place of destination of instruction?

Explanation: Only one memory operand can be specified in one instruction. Explanation: 8-bit or 16-bit operand cannot be used as a destination operand.

Which of the following is a invalid instruction?

Which of the following instruction is not valid? Explanation: Both the source and destination operands cannot be memory locations except for string instructions. Explanation: Since PUSH operation transfers data to stack from a register or memory location.

What are the instruction set of 8086?

x86