Early Computer Audio

Audio used to be easy. I remember programming the 6-bit DAC on the Tandy Color Computer in 6809 Assembler, and thinking… there’s nothing to this.

I then learned to program the Commodore SID chip. It introduced me to concepts like ring modulation, waveforms, and volume envelopes; it had a concept for the last of ADSR (attack-decay-sustain-release) that allowed you to control how long each stage of the sound’s volume lasted. Amazingly powerful stuff.

Later, I learned how to program the AY3-8913 sound chip in the Speech/Sound Pak. This chip was an amazingly powerful bit of kit for the time. It ultimately ended up powering the sound for the Atari ST – a machine favored by musicians because of the built-in MIDI controllers.

Here’s the sound demo that came with the Sound Pak for doing effects:

Some people have even used the hardware, torn apart and repurposed to do some beautiful things. Here is hacker Eric Archer’s reuse of the speech chip (SP0256-AL2) from a Tany Speech/Sound Pak to sing chords:

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