Abstract: The present invention includes a device for providing connections to a plurality of inputs of a circuit to be tested. A computer stores test vectors comprising data representing stimulus signals to be applied to the circuit and data representing response signals to be sensed from the circuit. The stored test vectors are applied through a driver associated with each input of the circuit to be tested. The driver has an output capable of assuming a high state, a low state or a floating state. A driver control causes the driver to assume a high or low output state in response to data representing stimulus signals and causes the driver output to assume a floating state in response to data representing response signals. Response signals from the device to be tested are compared to the data representing response signals to determine the occurrence of a fault.