Q. Evaluation Stack Architecture?
A stack is a data structure which implements Last-In-First-Out (LIFO) access policy. You can add an entry to the with a PUSH(value) as well as remove an entry from the stack with a POP( ). No explicit operands are there in ALU instructions however one in PUSH/POP. Illustrations of these computers are HP 3000/70, Burroughs B5500/6500 etc.
On a stack machine 'C = A + B'may be implemented as:
PUSH A
PUSH B
ADD // operator POP operand(s) and PUSH yield(s) (implicit on top of stack)
POP C
Stack Architecture: Pros and Cons
- Small instructions (don't require many bits to specify the operation).
- Compiler is easy to write.
- Lots of memory accesses needed - everything that's not on stack is in memory. So the machine performance is poor.