The PGM-4X4 is a multi-functional module that performs two different tasks. The main function is that of a programmer. Four columns of four separate control voltages can be individually chosen via the manual push-button or external gate inputs under each column. There is also an internal bus that allows direct normalized connection to the 4 gate outs of a separate FSR-4 (FSR-4 or FSR-4C family). The CV output range is selectable via internal jumpers to be either 0V to +5V or 0V to +10V (approximately) so that some rows can be set to be better suited for controlling more voltage sensitive destinations (such as the pitch of VCOs). When all four push-buttons are held for a couple of seconds, the PGM-4X4 converts into sequencer mode. In this mode the four column gate inputs and manual pushbuttons switch to sequencer duty. Their functions are shown on the front panel in parenthesis. These are the classic Clock in, Reset in, Run/Stop, and Manual Stepcontrols found on most sequencers. The PGM-4X4 can be chained to another PGM-4X4 to create a 4x8 programmer or a 4x8 sequencer. PGM-4x4s can also be stacked to add as many row outs as you have room in your cabinets, allowing such things as a 4 column by 12 row programmer or a 8 step by 8 row (or more) sequencer.