Texas Instruments TI-99/4

The TI-99/4 was a home computer built around Texas Instruments’ 16-bit TMS9900 processor and custom video, sound and system chips. Its console connected to a television or dedicated monitor and accepted software cartridges through a front slot.

It was the first mass-market 16-bit home computer, but its calculator-style keyboard, restricted BASIC environment and high introductory price limited its appeal. The design established the architecture later refined in the far more successful TI-99/4A.

Notable Features

• 16-bit TMS9900 CPU in an early consumer home computer
• TMS9918 video processor with sprites and colour graphics
• Speech, disk, memory and other options available through external expansion hardware

Historical Significance

• It was the first mass-market 16-bit home computer, but its calculator-style keyboard, restricted BASIC environment and high introductory price limited its appeal. The design established the architecture later refined in the far more successful TI-99/4A.

Collector’s Notes

• The original TI-99/4 is much less common than the 4A; its matching monitor, power supply and early software add context.
• 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-99/4
Manufacturer	Texas Instruments
Launched	Thursday, November 1, 1979
Discontinued	1981
Launch Price	$1,150
Country	United States
CPU	Texas Instruments TMS9900
Units Sold
Form Factor	Keyboard console
Power	External power supply
Networking	Optional through Peripheral Expansion Box
Operating System	TI BASIC
Expansion / I/O	Cartridge, cassette, joystick and expansion connector
Keyboard	41-key calculator-style keyboard
Storage	Cartridge; cassette; optional floppy disk
Sound	TI TMS9919 / SN94624 three-voice sound plus noise
Colours	16
Graphics	TMS9918: up to 256 x 192 pixels with 32 hardware sprites
Display	Television or dedicated composite monitor
ROM	System ROM and GROM containing console software and BASIC
RAM	16 KB CPU RAM plus 16 KB video RAM
CPU Speed	3 MHz