Apparatus for the dynamic in-circuit element-to-element comparison testing of electronic digital circuit elements
First Claim
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.
1 Assignment
0 Petitions
Accused Products
Abstract
Apparatus for the dynamic in-circuit testing of digital electronic devices employs a hardware testing circuit that is set by a microcomputer which takes no direct part in the test, so that the test hardware speed is not limited by the computer speed. The apparatus comprises a library of devices equivalent to the devices to be tested, the library including a ROM containing the information regarding the devices needed by the microcomputer for its purpose. An internal interface or router receives signals from the test device that are input signals to its terminals and routes them directly to the corresponding selected device in the library where it becomes an input to that device also. Signals from the test device that are output signals are routed instead to a comparison block where they are compared with the respective output signals from the library reference device. The signals at each corresponding pin of the two devices are compared and upon the presence of a fault the apparatus stops and identifies the pin or pins on which a fault has been detected. An external interface is provided to shift the signal levels as required between the test device and the transistor-transistor logic devices of the apparatus. The signals are sampled during timed periods to account for different propagation times through the apparatus, and different operating speeds of the devices. Provision is made for external or internal clocks, reset and ground connections.
-
Citations
28 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. 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 respective electric signals produced in the usual operation of the circuit in which the test element is connected; library means including a plurality of reference digital electronic elements each the same as or equivalent to a respective test element and having terminals corresponding to the respective terminals of the said respective test element, the library means also including memory means having therein information as to the operating parameters of each of the said reference elements; means for selecting a reference digital element from the said plurality thereof corresponding to the respective test element to be tested, comprising computer means for interrogating the memory means of the library means and subsequently effecting powering of the selected reference element in accordance with the information read by the computer means in the memory means for the selected reference element; and 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 corresponding terminals of the selected reference element and for producing a fault indication if the comparison indicates the presence of a fault. - View Dependent Claims (13, 14, 15, 16, 17, 18)
-
-
19. 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 respective electric signals produced in the usual operation of the circuit in which the test element is connected; library means including a reference digital electronic element the same as or equivalent to the test element to be tested and having terminals corresponding to the respective terminals of the test element, and memory means having therein information as to the operating parameters of the reference element; computer means for interrogating the memory means and subsequently effecting the powering of the said reference digital element to a powered state corresponding to that of the said test element; signal comparison means for comparing the signals at the said operative terminals of the test element with the corresponding signals at the respective corresponding terminals of the reference element in the library means and for producing a fault indication if the comparison indicates the presence of a fault; and means for feeding signals that are input signals to the test element from the accessing means to the library means and to the signal comparison means and for feeding signals that are output signals from the reference element from the library means to the signal comparison means.
-
-
20. A library module for use in apparatus for the dynamic in-circuit element-to-element comparison testing of a plurality of different electronic digital test elements while operative in their respective circuits and to which the apparatus is selectively connected, the library module comprising:
-
a circuit board having thereon a plurality of busbars; a plurality of electronic digital reference elements connected to the said busbars to permit the selective access to the terminals of each reference element; and a memory means connected to the said busbars for access by a memory interrogation means, said memory means having therein information for each reference element consisting of; (a) identification of the respective reference element, (b) identification of the busbars that are accessed for access to the respective reference element, (c) identification of the status of each operative contact of the respective reference element as to whether it is an input terminal, an output terminal, or a bidirectional terminal which may in operation be alternatively an output terminal or an input terminal. - View Dependent Claims (21)
-
-
22. Apparatus for the dynamic in-circuit, element-to-element comparison testing of an electronic digital circuit element while operative in its circuit comprising:
-
means for accessing at least the operative terminals of the test element for the connection of the test element to the apparatus; library means including a plurality of individually selectable different reference digital elements, each of which can constitute a reference digital element the same as or equivalent to a respective test element and having terminals corresponding to the respective terminals of the respective test element, and memory means having therein information as to the operating parameters of each of the said reference elements; 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; means for comparing a test signal at each operative terminal of the test element produced in the usual operation of the circuit in which the test element is connected with a corresponding signal which is a reference signal at the respective terminal of the reference element and for indicating a fault condition when the compared test and reference signals are different; means for connecting said accessing means, said selected, powered reference element and said comparing means; and routing means routing test signals which are input signals, test signals which are output signals and test signals which are bidirectional signals from said accessing means to the said comparing means, and routing test signals which are input signals and test signals which are bidirectional signals in input signal mode from the accessing means to the respective terminals of the said reference element; said connecting means connecting the reference element and the comparing means for transmission of reference signals which are output signals and reference signals which are bidirectional signals in output mode to the comparing means. - View Dependent Claims (23, 24, 25, 26, 27, 28)
-
Specification