# segment descriptor

> used for memory addressing in x86 computer architectures

**Wikidata**: [Q355694](https://www.wikidata.org/wiki/Q355694)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Segment_descriptor)  
**Source**: https://4ort.xyz/entity/segment-descriptor

## Summary
A segment descriptor is a data structure used for memory addressing in x86 computer architectures. It defines the properties and location of a memory segment, enabling features like protection and segmentation.

## Key Facts
- Used specifically for memory addressing within x86 computer architectures.
- Functions as a data structure defining the properties and location of a memory segment.
- Is a subclass of the computing component class "cache".
- Has the alias "Interrupt-Deskriptor".
- Is facet of the operating system domain.
- Has a Freebase ID: `/m/02pks4v` (source: Q15241312, 2013-10-28).
- Has a Microsoft Academic ID (discontinued): 2777779916.
- Is documented in 6 Wikipedia languages: de, en, ko, nl, pl, ru.
- Has 6 sitelinks across Wikipedia projects.

## FAQs
### Q: What is the primary function of a segment descriptor?
A: Its primary function is to define the properties and location of a memory segment for use in memory addressing within x86 computer architectures.

### Q: How does a segment descriptor relate to memory protection?
A: By defining segment properties like base address, limit, and access rights, segment descriptors enable memory protection mechanisms in x86 systems, preventing unauthorized access to memory areas.

### Q: Is a segment descriptor a type of cache?
A: No, segment descriptors are not cache themselves. However, they are classified as a subclass of the "cache" class within the provided knowledge hierarchy, which likely refers to the broader concept of data storage or management components.

### Q: Why are segment descriptors important in operating systems?
A: They are fundamental to the memory management and protection schemes implemented by operating systems running on x86 hardware, allowing for controlled and segmented access to the system's memory resources.

## Why It Matters
Segment descriptors are critical components in x86 architecture, forming the backbone of its memory management and protection systems. They allow operating systems to define and control access to different regions of memory (segments), enabling features like isolating code, data, and stack areas, enforcing privilege levels (rings), and preventing unauthorized memory access. This structured approach to memory addressing underpins system stability, security, and multi-tasking capabilities on billions of x86 processors worldwide. Without segment descriptors, the sophisticated memory protection and segmentation features characteristic of x86 systems would not be possible.

## Notable For
- Defining memory segment properties (base, limit, access rights) specifically for x86 addressing.
- Enabling hardware-enforced memory protection and privilege levels (rings) in x86 systems.
- Being a core data structure in the x86 segmentation memory model.
- Having a documented alias "Interrupt-Deskriptor".
- Being documented across 6 different language Wikipedias.

## Body
### Definition and Core Function
A segment descriptor is a data structure used exclusively for memory addressing in x86 computer architectures. Its primary purpose is to define the characteristics and location of a memory segment.

### Technical Role
- Defines key properties of a memory segment, including its base address, size (limit), and access permissions.
- Forms the basis for the x86 segmentation memory model.
- Enables hardware features like memory protection and privilege level enforcement.

### Relationships
- Classified as a subclass of the "cache" class within the provided knowledge hierarchy.
- Is considered a facet of the "operating system" domain.
- Has the alias "Interrupt-Deskriptor".

### Documentation
- Documented in the following Wikipedia languages: German (de), English (en), Korean (ko), Dutch (nl), Polish (pl), Russian (ru).
- Has a Freebase ID: `/m/02pks4v` (source: Q15241312, publication date: 2013-10-28).
- Has a Microsoft Academic ID (discontinued): 2777779916.
- Appears in 6 sitelinks across Wikipedia projects.

## References

1. Freebase Data Dumps. 2013