Abstract: An electronic testing system can test an electronic device which has more signal pins or pads (i.e., contacts) than the maximum number of tester probes. The testing system connects the contacts to the tester such that groups of contacts share individual tester signal lines. The testing system uses special selector logic on the device to be tested to determine which particular contacts of the groups are "currently output active", or capable of transmitting data. At each step in the testing procedure, the system can vary the sets of contacts which are chosen to be currently output active, thereby resulting in a high percentage of the possible states of the device being tested.