# Zilog Z80

> 8-bit microprocessor

**Wikidata**: [Q203315](https://www.wikidata.org/wiki/Q203315)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Zilog_Z80)  
**Source**: https://4ort.xyz/entity/zilog-z80

## Summary
The Zilog Z80 is an 8-bit microprocessor introduced in 1976 that became one of the most successful and widely used CPUs in computing history. It was designed as a compatible upgrade to the Intel 8080 and powered many early personal computers, game consoles, and embedded systems.

## Key Facts
- Introduced in March 1976 by Zilog, founded by former Intel engineer Federico Faggin
- Compatible with Intel 8080 instruction set but added approximately 80 new instructions
- Clock speeds ranged from 2.5 MHz to 8 MHz in various versions
- Manufactured by multiple companies including Zilog, Mostek, NEC, Toshiba, and Hitachi
- Used in iconic systems like the ZX Spectrum, Amstrad CPC, Sega Master System, and Game Boy
- Discontinued in 2024 after nearly 50 years of production
- Featured 16-bit address bus allowing access to 64 KB of memory
- Included built-in DRAM refresh controller and single +5V power supply

## FAQs
### Q: What computers used the Z80 processor?
A: The Z80 powered many classic computers including the Sinclair ZX Spectrum, Amstrad CPC series, MSX computers, Radio Shack TRS-80, and early CP/M machines. It was also used in game consoles like the Sega Master System and Game Boy.

### Q: Why was the Z80 so successful?
A: The Z80 succeeded due to its backward compatibility with the Intel 8080, improved instruction set, lower cost, and simpler power requirements. It became the processor of choice for many manufacturers and remained in production for nearly five decades.

### Q: Is the Z80 still used today?
A: The Z80 was officially discontinued in 2024 after almost 50 years of continuous production. However, it remains popular in retro computing projects, emulators, and some legacy industrial systems that continue to operate.

## Why It Matters
The Z80 represents a pivotal moment in computing history, bridging the gap between early 8-bit processors and the personal computer revolution. Its design philosophy of maintaining compatibility while adding features became a model for processor development. The chip enabled affordable home computers and gaming systems that brought computing to millions of people worldwide. Its longevity - nearly half a century of production - speaks to its robust design and the vast ecosystem of software and hardware that developed around it. The Z80's influence extends beyond its direct applications, as its architecture and instruction set informed later processor designs and established conventions still relevant in modern computing.

## Notable For
- Longest production run of any 8-bit microprocessor (nearly 50 years)
- Most successful second-source CPU, manufactured by over a dozen companies
- Foundation for CP/M operating system ecosystem and early software development
- Used in both home computers and game consoles, bridging two major computing markets
- Maintained backward compatibility while significantly expanding capabilities

## Body
### Technical Specifications
The Z80 featured an 8-bit ALU with a 16-bit address bus, allowing it to address up to 64 KB of memory. It included 16-bit registers (IX, IY, PC, SP) alongside 8-bit registers, providing enhanced addressing capabilities compared to its predecessor. The processor operated on a single +5V supply voltage, simplifying hardware design compared to the 8080's multiple voltage requirements.

### Architecture and Design
Designed by Federico Faggin and his team at Zilog, the Z80 maintained object code compatibility with the Intel 8080 while adding approximately 80 new instructions. This included block move operations, bit manipulation instructions, and improved interrupt handling. The chip featured a built-in DRAM refresh controller, reducing the complexity of memory systems.

### Manufacturing and Distribution
Unlike Intel's exclusive manufacturing model, Zilog licensed the Z80 design to multiple second-source manufacturers including Mostek, NEC, Toshiba, Hitachi, and others. This widespread manufacturing helped drive down costs and ensured availability, contributing to the processor's ubiquity in the late 1970s and 1980s.

### Applications and Legacy
The Z80 found use in diverse applications from home computers and game consoles to industrial controllers and scientific instruments. Its role in the CP/M operating system ecosystem made it central to early software development. The processor's influence extended to later designs, with derivatives like the Z180 and eZ80 maintaining backward compatibility while adding modern features.

### Derivatives and Successors
Zilog developed several Z80-compatible processors including the Z180 (with integrated peripherals), Z280 (16-bit internal architecture), Z380 (32-bit registers), and eZ80 (enhanced Z80 with 24-bit addressing). These maintained software compatibility while addressing evolving computing needs.

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## References

1. [Source](http://www.computerhistory.org/collections/catalog/102658073)
2. Freebase Data Dumps. 2013
3. [Source](https://www.techspot.com/news/102684-zilog-discontinuing-z80-microprocessor-after-almost-50-years.html)
4. National Library of Israel Names and Subjects Authority File