Propeller Chip

By Dale Dougherty

The head guy at Parallax, Chip Gracey, is truly self-taught, which means that he has had to find his own way. Twenty years after teaching himself to program the first generation of personal computers, the creator of the new Propeller microcontroller still speaks with the enthusiasm and amazement of a bright teenager: “The tools are out there. These days with the internet, it is so easy; you can learn anything. What used to be obscure stuff that only a few people were interested in — well, today those people put it on the net to share among themselves, and the rest of us have access to it.”

Lately he’s been “playing around” with speech waveforms because speech is really a spectral synthesis. “I’ve put about two steady years of work phenomenon.” So he believed the key to his into it. Just now, I’m on the cusp of having a working approach was to write programs that allowed him voice synthesizer.” He immediately starts walking to visualize speech patterns in more detail. “If you down the idiosyncratic path he took to get where can visualize it accurately then you know what he is today, and I do my best to follow along. He you have to do to re-create it.” conveys all the details as though they are keys to “I kept reading about digital resonators. Every-finding the levels of an adventure game he created. body talked about them but no one explained how

He explains how the key to speech synthesis they work. I couldn’t find a recipe. Then I finally is to reproduce vowel sounds, which are vocal came upon CORDIC math, which means coordinate resonators. The long sounds, the oohs and ahhs, rotation. [CORDIC is an acronym for Coordinate resonate inside the hollow spaces in our skulls Rotation Digital Computer.] It was developed in when we say words like “food” or “bath.” If he’s able the 50s. Real interesting stuff and very simple.” to replicate vocal resonance in software, the result He points to the computer screen where there will be something much closer to normal speech. are lines of code that don’t explain themselves. “I

“I used to look at the human voice on a scope realized that a CORDIC rotation algorithm could in high school and you can see the waveforms of be used to create a resonator. You just add in the speech. But you can’t look at speech in terms of stimulus vector (add x’s and y’s) and then rotate the

Photography by Robyn Twomey

76 Make: Volume 10