Texas Instruments TI-99/4A

The TI-99/4A refined Texas Instruments’ home-computer design with a full-travel keyboard, improved TMS9918A video hardware and a broad cartridge software library. The console retained the unusual 16-bit TMS9900 processor and serial expansion system.

Aggressive price competition made the 99/4A one of the best-selling American home computers of the early 1980s, but heavy discounting also contributed to TI’s withdrawal from the home-computer market in 1983.

Notable Features

• Full-travel keyboard replacing the TI-99/4’s calculator keys
• TMS9918A colour video with sprites
• Distinctive sidecar peripherals and optional Peripheral Expansion Box

Historical Significance

• Aggressive price competition made the 99/4A one of the best-selling American home computers of the early 1980s, but heavy discounting also contributed to TI’s withdrawal from the home-computer market in 1983.

Collector’s Notes

• Silver-and-black and later beige consoles exist. Power supplies, video standards and keyboards differ by region and revision.
• Memory, storage, displays and expansion hardware should be documented because configurations often changed during a system’s working life.

Specifications

Technical Information
Name	Texas Instruments TI-99/4A
Manufacturer	Texas Instruments
Launched	Monday, June 1, 1981
Discontinued	1984
Launch Price	$525
Country	United States
CPU	Texas Instruments TMS9900
Units Sold
Form Factor	Keyboard console
Power	External power supply
Networking	Optional RS-232 and third-party networking
Operating System	TI BASIC; optional Extended BASIC and p-System
Expansion / I/O	Cartridge, cassette, joystick and side expansion connector
Keyboard	48-key full-travel keyboard
Storage	Cartridge and cassette; optional floppy disk
Sound	TI SN76489-family three-voice sound plus noise
Colours	16
Graphics	TMS9918A: up to 256 x 192 pixels with 32 sprites
Display	Television or composite monitor
ROM	System ROM and GROM with TI BASIC
RAM	16 KB CPU RAM plus 16 KB video RAM; optional 32 KB expansion
CPU Speed	3 MHz