The TI-99/4A went on sale in June 1981 at $525, half the price of the TI-99/4 it replaced, with a full-travel keyboard swapped in for the calculator-style pad that had put buyers off the original. Under the hood it was still running a TMS9900, the same 16-bit processor family Texas Instruments used in its minicomputers, at a time when most home computers on the shelf next to it were built around 8-bit chips.
Why it matters
The 99/4A was TI’s second attempt at solving a problem entirely of its own making: a genuinely capable 16-bit CPU wrapped in a console TI had deliberately hobbled with GROM-based software and a closed cartridge system, sold at a price nobody wanted to pay. Cutting the price and fixing the keyboard worked. TI was shipping around 5,000 consoles a day from its Lubbock, Texas plant by late 1982, chasing Commodore’s VIC-20 and then the C64 down to street prices under $100. It shipped roughly 2.8 million units before TI pulled out of the home computer business in March 1984, having taken a $111 million loss in a single quarter getting there.
What to check before you buy
- Power it from a known-good original brick or a verified modern replacement. The internal PSU board expects 8V and 16V AC input, and wrong voltages have taken out logic chips on more than one forum thread.
- Ask about a recap. The power supply board's electrolytic capacitors are original-spec 1981-83 parts and a common source of no-power or wrong-voltage faults after four decades.
- Check for screen corruption or a picture that degrades after the first minute of use. Both point at either failing 4116 DRAM or a drifting video clock capacitor, two of the most commonly reported faults.
- If unlicensed or homebrew cartridges matter to you, check the title screen: consoles marked "(C)1983 TEXAS INSTRUMENTS V2.2" carry the later cartridge lockout chip.
- Cartridge and Peripheral Expansion Box card contacts oxidise with age; a "no response" cartridge is often a cleaning job, not a dead board.
- If buying a Peripheral Expansion Box setup rather than a bare console, confirm which cards are fitted and tested. The box and its disk/memory expansion cards are sold and priced separately from the console itself, and a bare console won't get you past 8 KB of usable RAM.
