SPECIAL TEST CHIP FOR TESTING IC TESTER.

IC testers having a limited number of tester pins have been improved in the prior art by multiplexing the connection of the testers' test pins to two or more of the input/output pads on the chips. A problem has arisen in the use of such multiplexed tester arrangements in testing the integrity of the electrical connections between the tester and the multiplexed I/O pads on the chips to be tested. If a short or open condition has occurred in one of the multiplexer switches between a tester pin and the IC pads, the only existing way to isolate and confirm the defective multiplexer switch is to disassemble the multiplexer. This problem is overcome, in accordance with the invention disclosed, by providing a special chip whose input/output pads are connected to either a first potential, for example, plus 5 v, or a second potential, for example, 0 v. All input/output pads corresponding to the 'A' side of the multiplexer switches can be connected to the first potential, and all input/output pads corresponding to the 'B' side can be connected to the second potential.