# Texas Instruments TI-99/4A

> home computer by Texas Instruments

**Wikidata**: [Q454390](https://www.wikidata.org/wiki/Q454390)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/TI-99/4A)  
**Source**: https://4ort.xyz/entity/texas-instruments-ti-99-4a

## Summary
The Texas Instruments TI-99/4A is a home computer developed and manufactured by Texas Instruments, released as an improved version of the earlier TI-99/4 model. It was produced from June 1981 to October 1983, with production officially ending in March 1984. The system runs on a 16-bit TMS9900 microprocessor and features a TMS9918 Video Display Controller for graphics.

## Key Facts
- Released: June 1981 as an improved version of the TI-99/4
- Discontinued: March 1984 after economic production ended in October 1983
- CPU: Texas Instruments TMS9900 16-bit microprocessor
- Manufacturer: Texas Instruments, an American multinational semiconductor company founded December 6, 1930
- Graphics: Uses TMS9918 Video Display Controller (introduced 1979)
- Sound: Features Texas Instruments SN76489 programmable sound generator chip (introduced 1979)
- Development: Created by Texas Instruments
- Classification: Home computer, computer model
- Origin: United States
- Software: Supports UCSD Pascal programming language system

### Q: What is the Texas Instruments TI-99/4A?
A: The TI-99/4A is a home computer produced by Texas Instruments from 1981 to 1984, featuring a 16-bit TMS9900 processor and improved graphics capabilities over its predecessor, the TI-99/4.

### Q: When was the TI-99/4A released and discontinued?
A: The TI-99/4A was released in June 1981 and economic production ended in October 1983, with official discontinuation in March 1984.

### Q: What processor does the TI-99/4A use?
A: The TI-99/4A uses the Texas Instruments TMS9900, a 16-bit microprocessor that was also used in the earlier TI-99/4 model.

## Why It Matters
The TI-99/4A represents an important chapter in the early home computer era, showcasing Texas Instruments' attempt to enter the consumer computing market with a system built around their own semiconductor technology. As a 16-bit home computer released during the early 1980s boom, it competed with other systems like the Commodore 64 and Atari computers, though it ultimately struggled in the marketplace. The system is notable for using TI's proprietary components, including the TMS9900 processor and TMS9918 graphics chip, demonstrating the company's vertical integration strategy. Its development and eventual discontinuation also reflect the challenges faced by major electronics companies attempting to diversify from their core businesses into the volatile home computer market of the early 1980s.

## Notable For
- First home computer to feature a 16-bit processor (TMS9900) in a consumer-priced system
- Used Texas Instruments' proprietary TMS9918 Video Display Controller for advanced graphics capabilities
- Featured the SN76489 sound chip, which became widely used in other computer and game systems
- Represented Texas Instruments' significant but ultimately unsuccessful entry into the home computer market
- Served as the successor to the TI-99/4, addressing many of that model's limitations

## Body
### Technical Specifications
The TI-99/4A is built around the Texas Instruments TMS9900 16-bit microprocessor, operating at approximately 3.0 MHz. This processor choice was notable for the time, as most home computers used 8-bit processors. The system includes 16 KB of VRAM for video display and 256 bytes of CPU RAM, with additional memory available through expansion.

### Graphics and Sound Capabilities
The computer uses the TMS9918 Video Display Controller, capable of displaying 16 colors with a resolution of 256x192 pixels in graphics mode. This chip was also used in other systems like the MSX computers and Sega consoles. For audio, the TI-99/4A incorporates the Texas Instruments SN76489 programmable sound generator, capable of three square wave channels and one noise channel.

### Software and Development
The system supports UCSD Pascal, a structured programming language system introduced in 1978. The TI-99/4A runs a proprietary operating environment and has its own BASIC programming language variant. Texas Instruments developed a range of software and hardware peripherals for the system, including a Peripheral Expansion Box for adding memory and interface cards.

### Market Position and Legacy
Released during the competitive early 1980s home computer market, the TI-99/4A faced stiff competition from more established players. Despite Texas Instruments' efforts to promote the system through retail channels and educational markets, it struggled to gain significant market share. The system's proprietary architecture and higher price point compared to competitors like the Commodore VIC-20 and later the Commodore 64 limited its commercial success.

### Related Systems and Components
The TI-99/4A directly follows the TI-99/4, addressing many of that model's limitations including the addition of lowercase character support and improved graphics capabilities. Both systems share the same TMS9900 processor and many architectural elements. The TI-99/4A's design philosophy reflects Texas Instruments' strategy of using in-house developed components across their product line.

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## 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