Most MIDI sound-sources (expanders) have at least 128 sounds or, in organ terms, stops. Whereas organs have drawknobs, rocker-tabs, pushbuttons, etc., to allow organists to conveniently turn stops on and off during performance, MIDI expanders have precious few, if any, comparable controls. Furthermore, organ consoles provide one drawknob, rocker-tab, etc., for each stop on the organ. MIDI expanders usually do not! The musician using an expander must decide which of the 128 stops the controls provided will actually control. For an organ console to provide traditional organ-stop access to MIDI-stops, a console would need at least 128 drawknobs for the MIDI sounds. Obviously, this is rather impractical in most situations. It is very expensive and there is usually not enough space on a console.

Another characteristic of a MIDI expander is that it is rather like a unit organ. To get the most from it, you need as many keyboards and stop-controls as possible to independently and simultaneously access as many stops as possible. Grouping all the MIDI-stops on one division is undesirable. Much preferable is to have some MIDI-stops in each organ division.

The underlying philosophy of the Classic Organ Works MIDI implementation is to integrate external MIDI-stops into the console so that:

• It is as easy as possible for the organist to access the external MIDI sounds during a performance as additional stops of the organ,
• The resources of the expander can be exploited to the maximum by the musician, and
• There is no limitation as to what expanders the organist may choose to use.

The Classic Console Control Computer allows an organ to have MIDI-stops on any or all divisions. Drawknobs or rocker tabs, or whatever controls the organ is equipped with, should be provided for MIDI-stops on more than one division, with at least one control for the pedal division. Because the Classic system fully integrates the MIDI-stops into the console operation, the stops can be coupled, set on pistons or transposed via the transposer just like any normal organ stop. An organist already familiar with standard console operation can easily use the MIDI-stops without any special instruction.

Another major advantage of the Classic approach is that organ builders can use MIDI hardware to generate sounds such as chimes, harpsichord, etc., as a low-cost way of providing these sounds and in a way that the organist does not even have to know that these stops are connected to the organ via a MIDI connection.

Most MIDI sound generators allow a few characteristics of the sound to be adjusted. These might be the MIDI channel number, the pan, the volume level, modulation, etc. The MIDI term for this collection of settings is patch. For each MIDI drawknob or tab on a console with a Classic Console Control Computer, the organist can set these values. Subsequently, when the organist draws the stop or when the stop is turned on via a piston, all the appropriate patch information is sent to the MIDI expanders that are attached. A later version of the Console Control Computer allows up to four MIDI Expanders to be connected at the same time, so that a patch may also specify which Expander to use.

To help the organist use the 128 or more sounds in the MIDI sound-generator(s) attached to the organ and the multitude of combinations thereof, the Classic Console Control Computer provides multiple MIDI levels. For example, if a console had 8 MIDI drawknobs the organist could set a different group of 8 sounds for each MIDI level configured on the organ. At the organist’s option, the MIDI levels can be changed by changing the combination-memory level.