Moog modular synthesizer
The first prototype Moog Modular Synthesizer, designed by Bob Moog was built in 1964 and by 1967 was a commercially available product line. These were walnut cabinets housing Moog 900-series modules.
The 900-series modules modules use S-Trigger and not the more widely used Gate. This drops +5V to 0V when a trigger is sent, the opposite of what’s commonly used in other synths, which raise 0V to a higher voltage.
- Wikipedia:Moog modular synthesizer