The TRS‑80 Voice Synthesizer

written by Matthew Reed

TRS-80 Voice Synthesizer from a Radio Shack catalog

TRS‑80 Voice Synthesizer from a
1981 Radio Shack catalog

The TRS‑80 Voice Synthesizer (catalog number 26-1180) was a speech synthesizer unit sold by Radio Shack. Introduced in 1979 for a price of $399.00, the unit was only compatible with the TRS‑80 Model I; Radio Shack never sold a TRS‑80 Model III version.

The TRS‑80 Voice Synthesizer plugged directly into the Model I expansion port and worked with both Level I and Level II BASIC systems. Like most voice synthesizers at the time, it worked by outputting words already broken into phonemes, or very small units of sound. It was described this way by the product introduction (under the headline of “Your TRS‑80 Speaks!”):

The new TRS‑80 Voice Synthesizer gives your Level-I or II TRS‑80 the capability of simulating human speech under program control.

There are 60 phonemes (elementary sounds) which, under your program’s control, are joined together by the computer to produce words. The words, in turn, may be joined together to form sentences. If you are writing an interactive program like the ones used in computer-assisted instruction, the Voice Synthesizer will allow you to verbally comment, clarify, and direct the program user.

This may seem far-fetched, but you’ll be convinced when you hear the demonstration cassette that comes with the Synthesizer! An instruction manual is also included.

Communicating with the unit was done in an unusual way. It “paralleled” thirty-two bytes of video memory, corresponding to the right half of the bottom screen line. Each phoneme was mapped to a different ASCII character and the synthesizer would speak any string of ASCII phonemes (bracketed by question marks) that was displayed on that part of the screen.

This odd method of addressing made it as easy as possible to output speech from a BASIC program. For example, the word “compute” could be spoken using this BASIC program line:


Although Radio Shack sold at least one program designed for the TRS‑80 Voice Synthesizer (Talking Eliza, catalog number 26-1908) and a handful of third-party programs supported it (Hyperlight Patrol from Fantastic Software was a notable example), the unit was clearly intended for people who wanted to write their own talking programs. Here is another quote from the product introduction:

With the new Voice Synthesizer, in many interactive programs, you can substitute voice output for information you would otherwise have printed on the video screen.

And, if you’re really creative, you can try to develop a conversational program that will converse “intelligently” when it doesn’t know what you are going to say! We warn you, it’s not easy!

After you hear it, we’re sure you’ll agree that this is a peripheral right out of the next century!

Radio Shack sold the TRS‑80 Voice Synthesizer until it was discontinued in 1983.

Categories: Hardware