Stack register
Encyclopedia
A stack register is a computer central processor register
whose purpose is to keep track of a call stack
. On an accumulator-based architecture machine, this may be a dedicated register such as SP on an Intel x86 machine. On a general register machine
, it may be a register which is reserved by convention, such as on the PDP-11
or RISC machines. Some designs such as the Data General Eclipse
had no dedicated register, but used a reserved hardware memory address for this function.
Machines before the late 1960s—such as the PDP-8
and HP 2100
—did not have compilers which supported recursion
. Their subroutine instructions typically would save the current location in the jump address, and then set the program counter to the next address. While this is simpler than maintaining a stack, since there is only one return location per subroutine code section, there cannot be recursion without considerable effort on the part of the programmer.
A stack machine
has 2 or more stack registers — one of them keeps track of a call stack
, the other(s) keep track of other stack
(s).
Processor register
In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are addressed by mechanisms other than main memory and can be accessed more quickly...
whose purpose is to keep track of a call stack
Call stack
In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, control stack, run-time stack, or machine stack, and is often shortened to just "the stack"...
. On an accumulator-based architecture machine, this may be a dedicated register such as SP on an Intel x86 machine. On a general register machine
Register machine
In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine...
, it may be a register which is reserved by convention, such as on the PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
or RISC machines. Some designs such as the Data General Eclipse
Data General Eclipse
The Data General Eclipse line of computers by Data General were 16-bit minicomputers released in early 1974 and sold until 1988. The Eclipse was based on many of the same concepts as the Data General Nova, but included support for virtual memory and multitasking more suitable to the small office...
had no dedicated register, but used a reserved hardware memory address for this function.
Machines before the late 1960s—such as the PDP-8
PDP-8
The 12-bit PDP-8 was the first successful commercial minicomputer, produced by Digital Equipment Corporation in the 1960s. DEC introduced it on 22 March 1965, and sold more than 50,000 systems, the most of any computer up to that date. It was the first widely sold computer in the DEC PDP series of...
and HP 2100
HP 2100
The HP 2100 was a series of minicomputers produced by Hewlett-Packard from the mid-1960s to early 1990s. The 2100 was also a specific model in this series. The series was renamed HP 1000 by the 1970s and sold as real-time computers, complementing the more complex IT-oriented HP 3000, and would be...
—did not have compilers which supported recursion
Recursion (computer science)
Recursion in computer science is a method where the solution to a problem depends on solutions to smaller instances of the same problem. The approach can be applied to many types of problems, and is one of the central ideas of computer science....
. Their subroutine instructions typically would save the current location in the jump address, and then set the program counter to the next address. While this is simpler than maintaining a stack, since there is only one return location per subroutine code section, there cannot be recursion without considerable effort on the part of the programmer.
A stack machine
Stack machine
A stack machine may be* A real or emulated computer that evaluates each sub-expression of a program statement via a pushdown data stack and uses a reverse Polish notation instruction set....
has 2 or more stack registers — one of them keeps track of a call stack
Call stack
In computer science, a call stack is a stack data structure that stores information about the active subroutines of a computer program. This kind of stack is also known as an execution stack, control stack, run-time stack, or machine stack, and is often shortened to just "the stack"...
, the other(s) keep track of other stack
Stack (data structure)
In computer science, a stack is a last in, first out abstract data type and linear data structure. A stack can have any abstract data type as an element, but is characterized by only three fundamental operations: push, pop and stack top. The push operation adds a new item to the top of the stack,...
(s).