Listening to "Atavachron" by Allan Holdsworth today, I was reminded of the unique design and capabilities of the SynthAxe, a system (much more than an instrument) that for a while in the late 1980's threatened to rewrite the landscape of guitar playing and guitar-based composition.
Sadly, today, the SynthAxe is approaching the status of a museum piece. Like the Synclavier, the cost and complexity of the instrumental package limited it to a small number of leading artists and musicians with money to spend. Fewer than 100 complete SynthAxe systems were produced, the company that made them went out of business a long time ago, and, like the Synclavier, the remaining operational and usable examples are being kept going by hobbyist ingenuity, and are truly labours of love. Holdsworth himself, a key SynthAxe endorsee in the early days, and the owner of 2 systems, only uses his sparingly in the studio, and will no longer use it live because of its fragility. Fortunately, you can hear the enormous potential of the instrument all over Holdsworth's recorded output over the last 25 or so years.
Here is an overview of the SynthAxe with promotional materials, maintained by an engineer who worked on it when it was being designed and built.