Hitachi, Ltd.

Koichi Mayama

Shigeru Yoshizawa

Mamoru Sugie

Yuzo Kita

Nobuo Saito

Noboru Yamaguchi

Hirokazu Aoki

Takashi Toyooka

Atsushi Asano

Shinsaku Chiba

A timing signal generating circuit including a clock source which generates clock pulses of a predetermined period, a binary counter which divides the frequency of the clock pulses from the clock source by n, a logical array which decodes an output of the binary counter and which is composed of semiconductor elements and flip-flop circuits which are set or reset by outputs of the logical array in response to the clock pulses from the clock source with the outputs of the flip-flop circuits being used as timing signals.

Timing signal generating circuit

In a memory device which has a plurality of recirculating type storage loops and in which information of the same addresses of the respective storage loops can be read and written in parallel, a memory device wherein information representing whether or not the corresponding storage loop is a bad or defective loop is written in a specified address of each of the storage loops.

Memory device with circulating storage loops

The present invention provides an improved method and apparatus for driving a magnetic bubble device, in which a d-c voltage supply and drive coils are connected to a bridge circuit consisting of four bi-directional switches, and alternating currents with steps (such as currents consisting of triangular waves or trapezoidal waves) are produced in the drive coils by suitably controlling the turn on or off of the bi-directional switches. As a result, the d-c level in the alternating current is not shifted by the variation in width of pulses which control the opening and closing of the bi-directional switches, and the magnetic bubble device is provided with a greatly improved operation margin.

Drive circuit for magnetic bubble device

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Mobara, Japan

Koichi Mayama