Laurie Spiegel's Appalachian Groove I from 1974:
The composer's web pages: http://www.retiary.org/
More specifically here:
but the entire web site is hers.
Some of her work at Bell Labs:
The Early Computer Arts at Bell Labs: http://www.retiary.org/ls/btl/btl.html
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko