OR (Chip)

The OR gate is a digital logic gate that implements logical disjunction. A 1 (high) output results if at least one of the inputs to the gate are 1 (high). If all inputs are 0 (low), a 0 (low) output results.

If no signal is connected to an input pin, the input is read as 0 (low). This is done by internal pull-down resistors that pull the signal to low in the absence of an input signal. Using this mechanism the OR gate can be used with 2 or 3 inputs in the exact same way.

Play with the 3 buttons to see the function of the OR gate. You will see that the output is only 0 (low) if all 3 inputs are 0 (low), in any other case the output will be 1 (high).