SP0256-AL2 IC picture

General Instrument SP0256-AL2

The SP0256-AL2 is a 1980s speech synthesizer chip manufactured by General Instrument. It is part of a family of ICs used to create computerized speech, and the most interesting as it can produce a variety of allophone sounds from input code. Combined with a controller of some sort (PC, microcontroller IC, dedicated chip, etc) to provide pronunciation, it can make a wonderfully trashy robot voice say whatever the user wanted. In your face, Alexa.

The difficulty of using such a chip is in the pronunciation: the chip accepts "phonemes" (short speech fragments) like "AY", "R", "OW", "ZH" etc. and needs a driver to hold its hand, dictating how it should combine these to form words. There was a standalone companion chip to do this - the CTS256 - but there's not much info on how that actually worked. Instead, I've adapted an existing algorithm from 1976 that uses simple rules to break speech into phonemes for the synth to use.

These days, nobody will check out your code unless it's IN TEH BROWSAR, so here's a webpage that lets you put in some text and get back .ogg audio of the chip reciting it. (This isn't an actual SP0256 or an emulator, it's using samples provided by little-scale. They are under CC-BY-NC 3.0 so think twice before you use this to voice a superhero in some mega-millions blockbuster.)

Also listen to what other people have submitted.

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