the present invention relates , in general , to an electronic and measuirng circuits are located remotely from the test head . a low device count circuit at each pin performs the necessary high speed switching . the force and measure lines are relatively long , but the signal rates are low enough to be accurately transmitted . the only high rate signals are on lines coupled to the gates of fet switches at the test head . thus , multiple pin , high speed testing can be accomplished using relatively small and inexpensive test heads .