Abstract: An automatic test apparatus coupled to a bit-directional internal data and control bus of a programmed microprocessor-based system tests the performance of the system in real time. Signal responses of the bus within a known good system are compared in real time to signal responses on the bus of an unknown system in order to identify faults. Faults are isolated by a sequential algorithm which stops operation at the occurrence of the first fault and thereupon traces the error to the subsystem or components supplying the indicated error signal to the bi-directional bus.

Abstract: A driver circuit for controlling the excitation of a multi-phase stepping motor is described which includes a switching power supply providing two average power output levels. The switching power supply provides a high voltage at the initiation of each excitation of a motor winding and a modulated voltage having an average at the normal operating level. The driver according to the invention eliminates need for dual power supplies and damper resistors.

Abstract: An apparatus for testing circuit board systems utilizing microprocessors which includes means for selectively exercizing each terminal or pin of the board system during each step of the testing protocol. Each step of the protocol can be preselected to operate according to an automatic sequence or according to a preprogrammed manner, or the apparatus may be conditioned to receive a response from the circuit board system at a selected terminal during a selected step of the testing protocol. The testing apparatus further includes an interactive interface to permit the board system under test to control the speed and sequence of the test procedure. The testing apparatus is capable of exercizing the board systems under test in a simulated environment at typically normal operating speeds so that degradation of system performance related to operational speed and other factors found in an operating environment can be analyzed.

Abstract: A device for testing the logic states of integrated circuits while operating in-circuit. The device includes a hand-held housing containing a pair of spaced circuit boards to which a clip is electrically coupled, the clip having terminals for making electrical contact with the pins on a test IC. The device has a circuit programmed for a particular IC by a socket having removable pins of different lengths. The socket has means for receiving a reference IC against which the test IC is to be compared. Switch means coupled with the circuit permit individual testing of the pins of the test IC.