The Model 220 programmable current source, and the Model 230 programmable voltage source are each supplied with a standard IEEE-488 interface. This interface adds an extra measure of versatility by allowing the transmission of data and commands over the IEEE-488 bus. The built-in IEEE interface provides all the logic necessary to interface the Models 220 and 230 to the bus using standard IEEE-488-1978 protocol. Additionally, the interface board incorporates a separate digital I/O port that may be used to interface the Models 220 and 230 to other digital instrumentation.