Texas Instruments TI-99/4A

The TI-99/4 series holds the distinction of being the first 16-bit personal computer. The TI-99/4A has a 16-bit TMS9900 CPU running at 3.0 MHz



The Texas Instruments TI-99/4A is a home computer, released June 1981 in the United States at a price of $525.

The TI-99/4 has a calculator-style chiclet keyboard and a character set that lacked lowercase text. The TI-99/4A added an additional graphics mode, “lowercase” characters consisting of small capitals, and a full-travel keyboard. Both use 16-bit processors, making the TI-99/4 series the first 16-bit home computers.

The TI-99/4A’s CPU, motherboard, and ROM cartridge (“Solid State Software”) slot are built into the keyboard. The power regulator board is housed below and in front of the cartridge slot under the sloped area to the right of the keyboard. This area gets very hot so users commonly refer to it as the “coffee cup warmer”. The external power supply, which was different according to the country of sale, is a step-down transformer.

Available peripherals included a 5ΒΌ” floppy disk drive and controller, an RS-232 card comprising two serial ports and one parallel port, a P-code card for Pascal support, a thermal printer, an acoustic coupler, a tape drive using standard audio cassettes as media, and a 32 KB memory expansion card. The TI-99/4 was sold with both the computer and a monitor (a modified 13″ Zenith color TV) as Texas Instruments could not get its RF modulator approved by the U.S. Federal Communications Commission in time[citation needed]. The TI-99/4A did ship with an RF modulator.

In the early 1980s, TI was known as a pioneer in speech synthesis, and a highly popular plug-in speech synthesizer module was available for the TI-99/4 and 4A. Speech synthesizers were offered free with the purchase of a number of cartridges and were used by many TI-written video games (notable titles offered with speech during this promotion were Alpiner and Parsec). The synthesizer uses a variant of linear predictive coding and has a small in-built vocabulary. The original intent was to release small cartridges that plugged directly into the synthesizer unit, which would increase the device’s built in vocabulary. However, the success of software text-to-speech in the Terminal Emulator II cartridge cancelled that plan. In many games (mostly those produced by TI), the speech synthesizer has relatively realistic voices. For example, Alpiners speech includes male and female voices and can be quite sarcastic when the player made a bad move.


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