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Apparatus for the dynamic in-circuit element-to-element comparison testing of electronic digital circuit elements

  • US 4,484,329 A
  • Filed: 08/10/1981
  • Issued: 11/20/1984
  • Est. Priority Date: 08/18/1980
  • Status: Expired due to Fees
First Claim
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1. Apparatus for the dynamic in-circuit, element-to-element comparison testing of an electronic digital test circuit element while operative in its circuit comprising:

  • means for accessing at least the operative terminals of the test element for its connection to the apparatus and consequent receipt from the said operative terminals thereof of the respective electric signals produced in the usual operation of the circuit in which the test element is connected;

    library means including a plurality of different reference elements and memory means having therein information as to the operating parameters of each of the said reference elements, each reference element being the same as or equivalent to the test element, and each having terminals corresponding to the respective terminals of the respective test element;

    computer means for interrogating the memory means and subsequently effecting powering of a selected reference element in accordance with the said information read by the computer means in the memory means for the selected reference element;

    signal comparison means for comparing the usual operation electric signals at the said operative terminals of the test element with the corresponding signals at the respective terminals of the reference element and for producing a fault indication if the comparison indicates the presence of a fault;

    means for feeding a signal which is an input signal at a terminal of the test element from said accessing means to the corresponding terminal of the reference element, and for feeding a signal which is an output signal at a terminal of the test element to the signal comparison means; and

    means for feeding a signal which is an output signal at a terminal of the reference element to the signal comparison means for comparison with the respective output signal from the test element.

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