# stack register

> computer central processor register whose purpose is to keep track of a call stack

**Wikidata**: [Q7595963](https://www.wikidata.org/wiki/Q7595963)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Stack_register)  
**Source**: https://4ort.xyz/entity/stack-register

## Summary
A stack register is a processor register whose purpose is to keep track of a call stack. It is a form of immediately accessible working storage inside a central processor used to record the position and state of the call stack during program execution.

## Key Facts
- The stack register is a subclass of "processor register," the immediately accessible working storage available as part of a digital processor.  
- Primary purpose: represents and keeps track of a call stack.  
- Common aliases include: stack pointer, SP, registro de stack, Stapelzeiger, Kellerzeiger, Stapelregister, Регистр стека.  
- Wikipedia title: "Stack register"; available in languages: de, en, es, fa, it, pl, zh, zh_yue.  
- Freebase ID: /m/027xm12.  
- Google Knowledge Graph ID: /g/121sxkmz.  
- Wikidata description: "computer central processor register whose purpose is to keep track of a call stack."  
- Sitelink count for the stack register entry: 9.  
- Parent class "processor register" has a sitelink_count of 46.  
- Implementations/related processors listed: Zilog Z80 (8-bit microprocessor; inception: 1976-03-00; sitelink_count: 41) and Intel 8080 (8-bit microprocessor; sitelink_count: 42).  
- Microsoft Academic ID (discontinued): 155355845.

## FAQs
### Q: What does a stack register do?
A: A stack register keeps track of a call stack. It records the processor-accessible position used to track calls and returns during program execution.

### Q: Is "stack register" the same as "stack pointer"?
A: Yes. "Stack pointer" and "SP" are listed aliases for the term "stack register."

### Q: Which processors use a stack register?
A: The stack register is used in many processors; the provided material lists the Zilog Z80 (8-bit microprocessor, inception 1976-03) and the Intel 8080 as related processors.

## Why It Matters
A stack register provides a hardware-level, immediately accessible location inside a processor to track the call stack. Because the call stack records return addresses, nested call depth, and related runtime state, the stack register plays a central role in how a processor manages subroutine calls and returns. As a dedicated register rather than memory-only bookkeeping, it enables efficient, low-latency updates and access to stack position during execution. This makes the stack register a foundational element of processor control flow and runtime state management. Its presence and behavior are often documented and named consistently across architectures (for example as "SP" or "stack pointer"), and it appears in historic 8-bit microprocessors such as the Zilog Z80 and Intel 8080, reflecting its long-standing role in CPU design.

## Notable For
- Explicitly represents and tracks the call stack at the processor-register level, rather than as purely external memory data.  
- Widely re-used naming and aliasing (e.g., "SP", "stack pointer") across languages and architectures.  
- Present in historically significant 8-bit microprocessors referenced in the source, including the Zilog Z80 (inception 1976-03) and the Intel 8080.  
- Identified in multiple knowledge systems (Freebase ID /m/027xm12, Google KG /g/121sxkmz, Microsoft Academic ID 155355845).

## Body
### Overview
- A stack register is a computer central processor register.  
- Its stated purpose is to keep track of a call stack.  
- It is categorized under the broader class "processor register."

### Naming and aliases
- Common aliases: stack pointer, SP.  
- Multilingual aliases provided: registro de stack (Spanish), Stapelzeiger / Stapelregister / Kellerzeiger (German variants), Регистр стека (Russian).  

### Relationship to processor register
- Subclass_of: processor register.  
- The parent class "processor register" is defined as immediately accessible working storage available as part of a digital processor (parent sitelink_count: 46).

### Implementations / occurrences
- The source lists specific related processors:  
  - Zilog Z80 — 8-bit microprocessor (inception: 1976-03-00; sitelink_count: 41).  
  - Intel 8080 — 8-bit microprocessor (sitelink_count: 42).  
- These listings indicate the stack register concept is associated with real CPU architectures in the provided material.

### Identifiers and metadata
- Wikipedia title: "Stack register" (available in de, en, es, fa, it, pl, zh, zh_yue).  
- Freebase ID: /m/027xm12.  
- Google Knowledge Graph ID: /g/121sxkmz.  
- Microsoft Academic ID (discontinued): 155355845.  
- Wikidata description: "computer central processor register whose purpose is to keep track of a call stack."  
- Sitelink_count for the stack register entry: 9.