Addressing

When using:

• the segmented memory model, the segment selector of the Stack Segment is the SS segment register
• the flat memory model, the stack can be located anywhere in the linear address space for the program.

Operations (PUSH|POP)

Items are:

• placed on the stack using the PUSH instruction
• removed from the stack using the POP instruction.

When an item is:

• pushed onto the stack, the processor decrements the ESP register, then writes the item at the new top of stack.
• popped off the stack, the processor reads the item from the top of stack, then increments the ESP register.

In this manner, the stack:

• grows down in memory (towards lesser addresses) when items are pushed on the stack
• and shrinks up (towards greater addresses) when the items are popped from the stack.