The A-164.1 has 3 push buttons that are used to generate three separate manual gate signals.
Gate 1 is a bit different: provided that no plug is connected to the input socket it behaves like the other two manual gates. If a control signal (e.g. rectangle output of an LFO) is fed into the input socket, the gate button 1 is working as a momentary on/off switch that is used to turn the signal on/off that appears at the two output sockets (mute function). Each Gate output has two sockets available (twin multiple).
Internal jumpers can be used to connect Gate 1 or Gate 3 to the gate line of the internal A-100 bus. That way the module can be used to control one or more envelope generators (such as the A-140) that are connected to the same bus board as the A-164. The gate outputs are "smoothed" to avoid contact bouncing.