Although algebraic expressions may be processed by simulating a stack on any computer, very few computers are true stack machines at the hardware level. Most computers are one- or two-address machines. The IBM 1130 was a one-address computer. The IBM 360 and its successors are two-address computers. Burroughs (Unisys) medium systems are three-address computers.
Stack machines are zero-address computers.
The number of addresses is specified with respect to the number of operand addresses included in a typical instruction.
A zero-address machine ADD instruction contains no operand addresses because the operands are implicitly the top two items in the stack.
A one-address machine ADD instruction contains one operand address because the other operand is implicitly the accumulator.
A two-operand machine ADD instruction contains the address of the first operand which is added to the second operand with the result being stored in one of the two operands.
A three-address ADD instruction contains the address of the first operand which is added to the second operand and stored in the third operand.
Burroughs stack mainframes use the stack for both data and control information. All operations, arithmetic, logical, and control, are performed using the stack.