Hitachi, Ltd.

Nippon Telegraph and Telephone Public Corporation

Kogyo Gijutsuin

Shigeru Yoshizawa

Nobuo Saito

Hirokazu Aoki

Takashi Toyooka

Mamoru Sugie

Minoru Hiroshima

Atsushi Asano

Koichi Mayama

Yuzo Kita

Noboru Yamaguchi

Nakahiko Yamaguchi

Yutaka Sugita

Masuo Kasai

Akira Kobayashi

Shinsaku Chiba

Minoru Saitoh

Shoji Yoshimoto

Hiroshi Suehiro

Yuji Arai

Keisuke Mise

Susumu Hibi

Itsuo Mikami

Gen-ichi Kamoshita

A series resonant drive circuit for a magnetic bubble memory includes X- and Y-coils arranged orthogonally to each other for generating a rotating magnetic field applied to a magnetic bubble memory chip, resonance capacitors each connected to a corresponding one of the X- and Y-coils for forming a series resonance circuit with the corresponding coil at a frequency of the rotating magnetic field, power supplies each connected to a corresponding one of the resonance circuits, and an inductance device connected in series with both of the resonance circuits and a capacitance device connected between the resonance circuits to compensate a mutual inductance due to the inductive coupling between the X- and Y-coils and a capacitance due to the capacitive coupling between the X- and Y-coils. Further, the temperature coefficient of the capacitance device is selected so that the temperature coefficients of the mutual inductance and capacitance between the coils can be compensated.

Series resonant drive circuit for magnetic bubble memory

A series resonance drive circuit for a magnetic bubble memory comprises a magnetic bubble memory chip or chips, X and Y coils arranged orthogonally to each other to form a rotating magnetic field in a plane of the chip or chips, resonance capacitors connected in series with the X and Y coils to form series resonance circuits with the X and Y coils at a frequency of the rotating magnetic field, A.C. power supplies connected to the resonance circuit, and a reactance device connected to the resonance circuits to compensate a mutual inductance due to a mutual inductive coupling between the X and Y coils and a capacitance due to a capacitive coupling between the X and Y coils. The reactance device includes a mutual inductance device, or an inductance device and a capacitance device.

Series resonance drive circuit for magnetic bubble memory

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

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

In a shift register type memory device wherein a plurality of chips are connected to a single sense amplifier and wherein data to be stored is cyclically written into the chips, then when a predetermined loop within a chip for stored designated data is defective, the data is not stored in a loop within the chip adjacent to the defective loop, but is stored in a loop to be subsequently read out in a chip to be read out subsequently to the chip having the defective loop.

Shift register type memory device consisting of a plurality of 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

A shift register type memory having major and minor loops, wherein the number of bits of the major loop is large enough to permit data of at least two blocks to simultaneously exist in the major loop when one block is constituted of data of bits the number of which is equal to the number of the minor loops, and wherein before a particular block having been transferred out from the minor loops to the major loop is again transferred in to the minor loops after travelling round the major loop, the next block is transferred out from the minor loops to the major loop.

Shift register type memory

A magnetic bubble information writing device capable of carrying out writing without erasing old information representing either '0' or '1' at a location, where new information is to be written, by means of only a single hairpin-like conductor loop is disclosed, in which the single hairpin-like conductor loop is disposed at a projecting portion of permalloy patterns, enclosing the portion.

Magnetic bubble information writing device

A magnetic bubble information writing device in which a conductor loop is disposed on the magnetic bubble propagation circuit and in which magnetic bubbles are generated by sending pulse current through the conductor loop, the device having a means which after having sent the bubble generating pulse current through the conductor loop, sends pulse current for annihilating stray bubbles through the same, the stray bubble annihilating pulse current having a polarity opposite to that of the bubble generating pulse current.

In a magnetic bubble module comprising magnetic bubble chips disposed on substrates and driving coils surrounding the magnetic bubble chips, at least one of the substrates extends from the inside to the outside of the coils and serves as a heat transfer plate. The heat transfer plate includes at least one metal foil having a thickness smaller than a skin depth of the metal.

Magnetic bubble module

A bubble domain driving apparatus is provided in which a large memory device with a storage capacity of 256 megabits, for example, is divided into 64 smaller memory elements, each thereof comprising one or plurality of thin magnetic film strips for bubble domain, and each of the 4-megabit smaller memory elements is provided with its own coils for applying in the plane thereof bubble domain driving rotating fields with the coils adapted to be selectively energized.

Growing community of inventors

Tokorozawa, Japan

Shigeru Yoshizawa