1. The means by which an encoding process is effected (see code). It may be implemented in hardware or software, the process being algorithmic in nature.
2. A logic circuit, usually an integrated circuit, that generates a unique n-bit binary word, indicating which of its 2n input lines is active, i.e. at logic 1. A keyboard encoder, for example, may be required to generate a unique binary code indicating which key on the keyboard has been pressed.
If two or more of the device inputs can be active simultaneously then a priority encoder is required, which usually encodes only the highest-order data input.