# WDC W65C816

> 8/16-bit microprocessor

**Wikidata**: [Q512020](https://www.wikidata.org/wiki/Q512020)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/WDC_65C816)  
**Source**: https://4ort.xyz/entity/wdc-w65c816

## Summary
The WDC W65C816 is an 8/16-bit microprocessor developed by Western Design Center and MOS Technology. It functions as a central processing unit (CPU) based on the MOS 6502 instruction set and is notably used in the Apple IIGS computer.

## Key Facts
*   **Classification:** The W65C816 is classified as a microprocessor and a central processing unit (CPU).
*   **Architecture:** It is an 8/16-bit processor utilizing the MOS 6502 instruction set.
*   **Developers:** The processor was developed by Western Design Center and MOS Technology.
*   **Manufacturer:** It is manufactured by Western Design Center.
*   **Notable Application:** It is related to the Apple IIGS, a 16-bit computer in the Apple II series.
*   **Aliases:** The entity is also known as the W65C816S, the 65816, and by the Arabic script name دبليو دي سي ٦٥٨١٦/٦٥٨٠٢.
*   **Identifiers:** It holds the Library of Congress Authority ID `sh86007999` and the National Library of Spain ID `XX531717`.

## FAQs
### Q: What type of processor is the WDC W65C816?
A: The WDC W65C816 is an 8/16-bit microprocessor designed to function as a central processing unit for computers.

### Q: Which computer system is associated with the WDC W65C816?
A: The processor is specifically related to the Apple IIGS, which is a 16-bit model within the Apple II series.

### Q: Who manufactures and develops the W65C816?
A: The microprocessor is manufactured by the Western Design Center. It was developed jointly by Western Design Center and MOS Technology.

## Why It Matters
The WDC W65C816 represents a significant evolution in microprocessor architecture by bridging the gap between 8-bit and 16-bit computing. Based on the widely adopted MOS 6502 instruction set, it provided a pathway for legacy systems to adopt more powerful processing capabilities without abandoning existing software ecosystems. This capability made it a strategic component in notable computing hardware, such as the Apple IIGS. By offering 16-bit performance while maintaining ties to the 6502 architecture, the W65C816 served as a versatile component for developers and manufacturers during a transitional period in personal computing history. Its continued documentation across multiple languages and library authorities underscores its enduring relevance in the history of microprocessor development.

## Notable For
*   **Hybrid Architecture:** Distinguished as an 8/16-bit microprocessor, allowing for flexibility between older 8-bit and newer 16-bit computing tasks.
*   **Instruction Set Heritage:** Utilizes the MOS 6502 instruction set, connecting it to one of the most influential processor lineages in early computing.
*   **Hardware Integration:** Served as a core component in the Apple IIGS, a significant model in the Apple II series.
*   **Global Recognition:** It is cataloged by major international libraries, including the Library of Congress and the National Library of Spain, and has Wikipedia entries in over 10 languages.

## Body
### Development and Classification
The W65C816 is a microprocessor, a class of computer processor contained on an integrated-circuit chip. It is further classified as a central processing unit (CPU), the central computer component that executes instructions. The device is attributed to developers Western Design Center and MOS Technology, with Western Design Center serving as the primary manufacturer.

### Technical Specifications
The processor is defined by its hybrid 8/16-bit architecture. It is built upon the MOS 6502 instruction set, which serves as its foundation for executing commands. This design places it within the lineage of the 6502 family while expanding its data-handling capabilities.

### Usage and Relations
The most prominent hardware relation for the W65C816 is the Apple IIGS. The Apple IIGS is identified as a 16-bit computer belonging to the Apple II series. The integration of this CPU into such a system highlights its utility in bridging the gap between the 8-bit era and the 16-bit era of personal computing.

### Identification and Documentation
The microprocessor is documented under various identifiers and titles across academic and technical repositories.
*   **Titles/Aliases:** W65C816S, 65816.
*   **Library IDs:**
    *   Library of Congress Authority ID: `sh86007999`
    *   National Library of Israel J9U ID: `987007531942105171`
    *   National Library of Spain ID: `XX531717`
*   **Digital Presence:** It maintains a presence on Wikipedia across multiple languages including English, German, French, Spanish, Japanese, and Arabic, and is categorized under "Western Design Center 65C816" on Wikimedia Commons.

## References

1. [Source](https://github.com/JohnMarkOckerbloom/ftl/blob/master/data/wikimap)
2. Freebase Data Dumps. 2013
3. National Library of Israel Names and Subjects Authority File