PUSH and POP Instructions

The instruction first decrements and then copies either a 16- or 32- bit source operand into the stack. A 16-bit operand causes to be decremented by 2. A 32-bit operand causes to be decremented by 4.

PUSH — Push Word(s) onto Stack

Usage: PUSH src

Flag O D I S Z A P C
Result                

Decrements by the size of the operand (two or four, byte values are sign extended) and transfers one or two words from source to the stack top.

Clocks
Operands 286 386 486 Size Bytes
reg16 3 2 1 1
reg32   2 1 1
mem16 5 5 4 2-4
mem32   5 4 2-4
segreg 3 2 3 1
immed 3 2 1 2-3


The instruction removes a value from the stack and places it in a register or variable. After the value is popped from the stack, the stack pointer is incremented to point to the next-highest location in the stack.

POP — Push Word(s) off Stack

Usage: POP dest

Flag O D I S Z A P C
Result                

Transfers word(s) at the current stack top pointed by to the destination then increments to point to the new stack top.

Clocks
Operands 286 386 486 Size Bytes
reg16 5 4 4 1
reg32     4 1
mem16 5 5 6 2-4
mem32     6 2-4
segreg 5 7 3 1





      “You win the gold, you feel good. You win the bronze, you think,    
      ‘at least I got something.’ But you win that silver, that’s like,    
      ‘Congratulations, you almost won! Of all the losers, you came in first!’”    
      ― Jerry Seinfeld