Question

A stack is organised such that SP always points at the fourth empty location on the stack. List the micro operation for push and pop operations

Answer 1

Answer:

Stack Organization

A useful feature that is included in the CPU of most computers is a stack or last-in, first-out (UFO) list. A stack is a storage device that stores information in such a manner that the item stored last is the first item retrieved.

The stack in digital computers is essentially a memory unit with an address register that can count only (after an initial value is loaded into it).

The register that holds the address for the stack is called a stack pointer (SP) because its value always points at the top item in the stack.

The two operations of a stack are the insertion and deletion of items. However, nothing is pushed or popped in a computer stack. These operations are simulated by incrementing or decrementing the stack pointer register.

Register Stack A stack can be placed in a portion of a large memory or it can be organized as a collection of a finite number of memory words or registers. Figure 3 shows the organization of a 64-word register stack. The stack pointer register SP contains a binary number whose value is equal to the address of the word that is currently on top of the stack. Three items are placed in the stack: A, B, and C, in that order. Item C is on top of the stack so that the content of SP is now 3.