The simplest form of combination action memory.
Consists of a matrix array of switches for each department (Pedal, Accompaniment, Great, etc.) where the rows correspond to the pistons (so if there are 10 pistons to a department, then there are 10 rows of switches) and where the columns correspond to the stops (so if there are 55 stops in a department, then there are 55 columns of switches). Each switch can be placed in an ‘on’, ‘off’ or ‘neutral’ position, so determining which stops are moved on or off when a particular piston is pressed.
The neutral position leaves the stop position unaltered when the piston is pressed, useful (for example) in the control of tremulants.
On smaller instruments the setter-board can be located in the back of the console or behind the knee-board. Larger instruments can have quite massive setter boards which may be located in a separate room.
As well as the setter-board, this type of combination action also requires a multi-contact relay for each piston, the number of contacts equalling the number of stops controlled by each piston. These are located close to the setter-board to reduce wiring runs.