Chord organ is a kind of home organ that has a single short keyboard and a set of chord buttons, enabling the musician to play a melody or lead with one hand and accompanying chords with the other, like the accordion with a set of chord buttons which was originated from a patent by Cyrill Demian in 1829, etc.
Initially, the chord organ was invented as a kind of electronic home organ by Laurens Hammond in 1950. This was followed by the reed chord organ (c. 1959) and Optigan (c. 1971). The sound of the reed chord organ is somewhat similar to the harmonium or the accordion.