Here are some sound clips of a Hammond X66 with MIDI capability

MIDI, which stands for Musical Instrument Digital Interface, is an interesting technology whereby various MIDI-equipped musical instruments can communicate with and control other MIDI compatible instruments. For our purposes here, MIDI makes it possible for a MIDI-equipped Hammond organ to control and play other instruments, such as keyboards, digital pianos, MIDI sound modules and even the sound cards in computers.
For example, a MIDIfied organ console can simultaneously play all the sounds and effects in a modern keyboard. This means that one person sitting at such an organ console can play and use all of the many sounds that the organ produces and also simultaneously play MIDI instrument sounds from the keys and pedals of the organ. This makes it possible to combine the two different instruments and place both under the control of just one person. It also makes possible a virtually infinite variety of possible sounds as the two instruments can be combined in any imaginable way regarding their individual tonal possibilities.
At Main Street Music, we have the capability of adding MIDI functionality to older Hammond organs, which results in a new instrument that combines all of the great features of Hammond organs with the means to exploit and use all of the excellent instrumental sounds that are possible with a modern digital keyboard.
Listen closely to these sound clips and you will soon realize that there is virtually no limit to the musical possibilities.

Keyboards and controls of a Hammond X66