JPS622391B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an improvement in an operation testing method for bubble memory devices.

(b) Background of the technology Bubble memory elements are made by applying a perpendicular bias magnetic field to the surface of a magnetic thin film to detect the presence or absence of magnetic bubbles.
This is a non-volatile serial magnetic memory element that has a configuration in which the signal train caused by magnetic bubbles is shifted by applying a local gradient of a bias magnetic field to correspond to 1 and 0 in binary information, and is transferred through a predetermined bubble transmission path. . The bubble transmission path is formed by applying an in-plane rotating magnetic field to a T1, chevron or half-disk shaped magnetic material such as a permalloy pattern, which is obtained by placing it in contact with the magnetic thin film at each bit position, or a local magnetic field obtained by energizing a conductor pattern. Thus, we can obtain local perpendicular magnetic field gradients in the magnetic thin film, e.g.
10 ^6- bit effective magnetic bubbles at the same time and efficiently.
A magnetic memory is created by selectively controlling movement, generation, disappearance, expansion, division, etc.

(c) Prior art and problems In order to guarantee the functionality of the magnetic bubble memory element, a rotating magnetic field H _R is applied to the magnetic bubble memory element using the configuration and driving method shown in FIG.
is applied to move the magnetic bubble. 1st
1a is a block diagram of the coil drive circuit, FIG. 1b is a time chart of the coil drive signal, and FIG. 1c is a time chart of the current flowing through the coil. L _X , L _Y are coils, S _X1a , S _X1b , S _X2a , S
_X2b , S _Y1a , S _Y1b , S _Y2a , and S _Y2b are switching elements, and although they are shown as mechanical contacts, they are normally constructed by current switches using semiconductor elements, and the coils L _X and L _Y are assumed to be arranged at right angles. . And, like other memories, magnetic bubble memory devices are subjected to continuous operation tests, environmental cycles, physical shock tests, etc. as necessary, to ensure DC performance and other data retention functions of operation tests. However, these are based on the coincidence of malfunctions that occur when the driving conditions are changed at a constant rate, for example, the driving voltage. It is not possible to determine whether a malfunction has occurred during movement of the permalloy pattern or when a magnetic bubble jumps over the gap between two adjacent permalloy patterns, resulting in unnecessarily long test times and rapid failure analysis. There was a drawback that I couldn't do it.

(d) Object of the invention The object of the invention is to eliminate the above-mentioned drawbacks _.
By setting one or more short off-times at arbitrary positions in the coil drive signal to generate a pseudo noise in the rotating magnetic field, this method is an efficient means for magnetic bubble memory testing and a quick error generation mode. It is intended to provide a means of analysis.

(e) Structure of the Invention The object is to apply a bias magnetic field and a rotating magnetic field to two sets of rotating magnetic field coils oriented at right angles in order to generate the rotating magnetic field in a bubble memory element that drives a magnetic bubble by applying a bias magnetic field and a rotating magnetic field. a pulse generating means that generates a pulse having a single or plural preset time widths at an arbitrary phase position of a two-phase drive signal; and a pulse generated by the pulse generating means that directs the drive signal to the rotating magnetic field coil. a drive signal blocking means for blocking application of the bubble, and the drive signal blocked by the drive signal blocking means is applied to each of the rotating magnetic field coils to test the operation of the bubble memory element. This can be achieved by providing a method for testing memory devices.

(f) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings. FIG. 2a shows a block diagram of a test method for a bubble memory device according to an embodiment of the present invention, and FIG. 2b shows a time chart of a coil current. In the figure, 1 is a bubble memory element, 11
12 is a control unit; 12 is a drive signal timing generator;
13 is a pulse generator that sends out a pulse of opposite polarity at an arbitrary phase position of a drive signal for pseudo-interference, 14 is an AND circuit, and 15 is a coil drive circuit.

In the configuration shown in the figure, when the pulse generator 13 does not send out a pulse of opposite polarity, the timing generator 12 sends out a drive signal similar to the conventional drive signal shown in FIG. Then, the coil drive circuit 15 via each AND circuit 14 drives the drive coils L _X and L _Y of the bubble memory element 1 to generate a rotating magnetic field and move the magnetic bubble one step every cycle.

However, in one embodiment of the present invention, the control unit 1
Although 1 is not shown, the pulse generator 1 is operated according to the control program and control data stored in the storage unit.
3 and sends out a reverse polarity pulse with a preset pulse width at an arbitrary phase position of the drive signal as shown in b-2 of FIG. Since the circuit 14 cannot obtain a logical product for the reverse polarity pulse portion, the input signal applied to the coil drive circuit 15 has teeth missing in the reverse polarity pulse portion as shown in b-1 of FIG. The coil current of the section, here L _Y
The current changes discontinuously as shown at b-3 in FIG.
Therefore, if the control unit 11 controls this phase to change one by one, an effect similar to that of pseudo-superimposing noise at an arbitrary phase position can be obtained, which is the same effect as described in (c) Prior Art and Problems above. It is easy to reproduce a test in which a magnetic bubble, for example, jumps over a gap between permalloy patterns during a transfer operation using permalloy patterns, and a malfunction occurs due to insufficient rotating magnetic field. The above explanation _was made by superimposing one reverse polarity pulse on _L It goes without saying that they can be superimposed in the same way.

(g) Effects of the Invention As explained above, according to the present invention, when testing the operation of a bubble memory element, a pseudo pulse is superimposed at an arbitrary phase position in the drive signals of _the coils _L In addition to providing an efficient test method by generating pseudo noise in a magnetic field, it is also possible to provide an effective test method that provides a means for analyzing error occurrence modes.

[Brief explanation of the drawing]

FIG. 1a is a block diagram of a coil drive circuit for a conventional bubble memory element and an embodiment of the present invention, FIG. _1b is a time chart of the drive signal, and _FIG . FIG. 2a is a block diagram of a test method for a bubble memory device according to an embodiment of the present invention, and FIG. 2b is a time chart thereof. In the figure, 1 is a bubble memory element, 11 is a control unit, 12 is a timing generator, 13 is a pulse generator, 14 is an AND circuit, 15 is a coil drive circuit, and L _X and L _Y are rotating magnetic field coils of the bubble memory element. It is.

Claims (1)

[Claims] 1. In a bubble memory element that drives a magnetic bubble by applying a bias magnetic field and a rotating magnetic field, any phase of two-phase drive signals applied to two sets of rotating magnetic field coils oriented at right angles in order to generate the rotating magnetic field. a pulse generating means for generating a pulse having one or more preset time widths at a position; and a driving signal blocking means for preventing application of the driving signal to the rotating magnetic field coil by the pulses generated by the pulse generating means. A method for testing a bubble memory device, comprising: testing the operation of the bubble memory device by applying the drive signal blocked by the drive signal blocking means to each of the rotating magnetic field coils.