Products go out of production for a lot of reasons. Sometimes critical components or materials become obsolete and unavailable. In other cases economics change and another device comes along that does the same job better or at lower cost. None of these products are currently in production but this doesn't take away from the influence that they had when they were introduced. We often get email from builders involved in restoring these and other early products and we're pleased to help in any way possible.
The PAiA OZ Mini-organ included a capacitive hand pad which converted pressure into pitch bends. It was a great Gnome "front end" as a polytonic pitch source (external audio input signal/trigger source). Here's the original Radio Electronics article in pdf format.
The PAiA P4700/J, modular analog synthesizer kit package, featured a 6503 processor-based micro-controller and firmware for polyphony. Sequencer and algorithmic composition programs were among others also available. Modules from this series are often sold on eBay and other on-line auction sites. Old Crow's restoration in the Hall of Fame has many detailed photos.
John Simonton (left) and Marvin Jones (Editor of Polyphony magazine) at the Anaheim NAMM show in about 1974. - it's this set-piece, see, and you pay a buck and get a picture that makes your friends think you were on the cover of Rolling Stone. Don't recall the exact date - it was the 70's ... ya' know?