Binary or Boolean logic is a way of combining gate signals (on or off voltages) to create new outputs. Each section of a logic module typically includes 1 to 3 inputs, with 2 being the most common. Here are some of the most common logic functions:
- An OR function says if there is a gate on (or “high”) signal at any of the inputs (i.e. input 1 or input 2 or input 3, etc.), to output a gate on signal.
- An AND function says only output a gate on signal if all of the inputs see “high” gate signals (i.e. input 1 and input 2 etc. all have gate ons).
- Adding an “N” to the front of a function’s name says “not” this function – in other words, a NOR function would only output a high signal if all inputs were low (not input 1 nor input 2 are high).
Other common logic functions are inverters (often symbolized with a bar over the top of a letter corresponding to the input), and flip-flops that toggle between high and low every time they receive an input trigger (i.e. the first trigger would set the output high, the second trigger sets it low again, and so on).
(Logic is also the name of a popular and long-lived MIDI sequencing program and DAW. But this site is about modular synths, and there are logic modules available.)