Hitachi, Ltd.

Nippon Telegraph and Telephone Public Corporation

Nakahiko Yamaguchi

Shigeru Yoshizawa

Yutaka Sugita

Nobuo Saito

Akira Kobayashi

Shoji Yoshimoto

Yuji Arai

Susumu Hibi

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.

Method and apparatus for testing a magnetic bubble memory

A field access magnetic bubble memory device including a memory chip applied with an in-plane magnetic field at need is disclosed. At a transient stop operation of the device before its interrupted state, an in-plane field is removed after it has been held for a predetermined period following the cessation of rotation thereof. The in-plane field may be increased upon the cessation of rotation thereof. At a transient start operation of the device after the interrupted state, an in-plane field having no rotation and the same direction as at the transient stop operation is applied for a predetermined period before the initiation of rotation thereof. The applied in-plane field may be increased upon the initiation of rotation thereof.

Field access magnetic bubble memory device

Growing community of inventors

Sayama, Japan

Nakahiko Yamaguchi