One-hot

In digital circuits, one-hot refers to a group of bits among which the legal combinations of values are only those with a single high (1) bit and all the others low (0). For example, the output of a decoder is usually a one-hot code, and sometimes the state of a state machine is represented by a one-hot code. A similar implementation in which all bits are '1' except one '0' is sometimes called one-cold.