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Method-and-apparatus-for-testing-a-magnetic-bubble-memory

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Method and apparatus for testing a magnetic bubble memory

Details

Inventors: Yamaguchi, Nakahiko; Hibi, Susumu; Yoshizawa, Shigeru; Yoshimoto, Shoji; Kobayashi, Akira;
Assignee: Nippon Telegraph and Telephone Public Corporation (both of, JP); Hitachi, Ltd. (both of, JP)
Primary Examiner: Moffitt; James W.
Assistant Examiner:
Attorney, Agent or Firm: Craig & Antonelli

Method and apparatus for testing a magnetic bubble memory are disclosed wherein a most severe magnetic bubble domain arrangement which fully causes the ununiformity of magnetic interaction between magnetic bubble domains is experimentally determined, and a basic pattern [P] and a test information pattern determining an arrangement of the basic patterns [P] and complementary patterns [P] thereof for realizing that magnetic bubble domain arrangement are stored in memory units, respectively, and the basic patterns [P] and the complementary patterns [P] are sequentially read out in accordance with the test information pattern to generate magnetic bubble domain trains in a storage area of the magnetic bubble memory. The magnetic bubble domain trains are then read out by a magnetic bubble detector and the read-out signals are converted to logical signals by a sense amplifier unit and the logical signals are synchronized with logical signals corresponding to the test information pattern and compared therewith to produce an identity or non-identity signal and thus the disclosed method and apparatus for testing the magnetic bubble memory can exactly evaluate a memory characteristic of the magnetic bubble memory.

DETAILED DESCRIPTION It is an object of the present invention to provide a method and apparatus for simply and exactly evaluating the memory characteristic of the magnetic bubble memory.
More particularly, it is a first object of the present invention to provide a method for testing the magnetic bubble memory by utilizing a magnetic bubble domain arrangement pattern which realizes a worst condition magnetic bubble domain arrangement pattern.
It is a second object of the present invention to provide an apparatus for testing the memory performance of the magnetic bubble memory comprising a circuit device for generating a magnetic bubble arrangement pattern to the storage area of the magnetic bubble memory with a worst condition, a signal input circuit device for introducing said pattern in the storage area; a signal output circuit device for deriving the pattern as electrical signal pattern after the pattern is circulated once or plural times, and a comparing circuit for comparing said electrical signal pattern with the magnetic bubble arrangement pattern input with worst condition.
According to one aspect of the present invention, there is provided a method for testing the magnetic bubble memory comprising the steps of storing a basic pattern [P] represented by binary notation in a first memory unit and storing a test information pattern determining the arrangement of the basic patterns [P] and complementary patterns [P] thereof in a second memory unit; sequentially reading the basic patterns [P] and the complementary patterns [P] in accordance with the test information pattern; converting those patterns into logical signals corresponding to the binary notation and then producing a magnetic bubble pattern corresponding to the test information pattern in a storage area of the magnetic bubble memory by a driver through a test mode switching unit; converting magnetic bubble domain trains of the magnetic bubble pattern into logical signals through a magnetic bubble domain detecter unit and an output amplifier unit; comparing the logical signals corresponding to the magnetic bubble domain trains with the logical signals corresponding to the test information pattern by a comparator unit to determine identity or non-identity thereof; and evaluating a memory characteristic of the magnetic bubble memory by an output of the comparator unit

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