First, in 2007 Matrix covered Greg Danner’s restoration of the notorious Sal-Mar Construction, an obscenely complex synthesizer from 1969 controlled by digital logic sequencers. What you didn’t know: Greg has a Flickr account full of photos of the restored Sal-Mar.
Also in 1969, Joel Chadabe had Moog build a modular synth along roughly similar lines–no keyboard, lots of sequencers. The innards of the CEMS are documented here.