Application of microprocessor in digital testing with special reference to magnetic core memory systems
The reduced size and cost and the ability to program microprocessors make them ideal for use in test instruments.
As most available microprocessors are MOS devices, their application in testing high speed digital and analog units is usually restricted by their relative slow operating speed. This speed limitation can be overcome either by modifying the controller structure or by altering the test method. The fonner approach,
in general, requires additional or expensive high speed components whereas the latter includes the application of test methods which can be described as 'dynamic' or 'semidynamic'.
These two test methods are discussed in this dissertation and a quantitative analysis shows that if a high speed test pattern repetition rate is not a necessary requirement, the semidynamic method which tests and analyzes a 'unit under test' on a real-time basis will result in a faster and simpler configuration. Comparison of both methods under specific conditions are also made and the possibility of modifying the systems to fit different requirements are investigated.
In the present study, a microprocessor-based magnetic core memory test system is constructed to illustrate the proposed semidynamic test method which incorporates a controller and the associated test interfaces. Design criteria for the controller for various applications are covered, and the test interface design and implementation for the present application is discussed. The test interfaces include functional test and environmental
test parts, which generate the necessary test patterns and monitor a set of corresponding environmental parameters respectively. Although the environmental parameters may differ in nature for
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different 'units under test', it can be seen that essentially they can be controlled by analog signals. Hence control of these parameters merely becomes the control of some prograrrunable analog voltages. The idea is implemented by constructing the required environmental test interfaces in the present project.
For the system software, factors governing choice of
a suitable programming language to meet different testing needs are examined and the design of the monitor and test programs is discussed. Some possible modifications to improve the operation of the test system under certain conditions are also suggested.
Operation of the test system built along the lines of the earlier proposals is verified by testing a magnetic core memory module and the results obtained show that it performs the specified tests in a satisfactory manner which suggests that the proposed semidynamic approach is a viable solution to the problem of testing high speed units using a relatively low speed microprocessor. In addition, the test system provides facilities for testing different 'units under test' by changing the program memory, and by making small modifications to the system hardware.
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School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:microprocessors electric testing digital electronics magnetic memory calculating machines
Date of Publication:01/01/1979