Abstract: An electronic musical instrument has the switch contacts associated with the keyboard and with the other user operated controls arranged in a single matrix with the switch contacts being grouped in the matrix such that, for example, all of those switches associated with keys are in one corner of the matrix. This arrangement and grouping of switch contacts allows the matrix to be scanned, under the control of logic circuitry, such that those switch contacts associated with the keyboard keys are more frequently scanned than are those switches associated with the other inputs. Information for controlling an audio tone generator is provided in digital form as a function of the state of the contacts of the switches comprising the matrix, the audio frequency signals being digitally synthesized.