Wikipedia
One-hot
Binary
Gray code
One-hot
000
000
00000001
001
001
00000010
010
011
00000100
011
010
00001000
100
110
00010000
101
111
00100000
110
101
01000000
111
100
10000000
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). A similar implementation in which all bits are '1' except one '0' is sometimes called one-cold.