DE1524785A1 - Electrically changeable matrix-shaped semi-fixed storage with thin magnetic layers - Google Patents

Description

Dipl.-Ing. Heinz Ciaessen
Patent attorney
7 Stuttgart 1
Rotebühlstrasse 70

ISE / Reg. 3639

A.J.Judeinstein-J.N.L. Kraxt nee Bezaguet 10-3

INTERNATIONAL STANDARD ELECTRIC CORPORiITION, NEW YORK

Electrically changeable matrix-shaped semi-fixed value memory with thin magnetic ones layers

The priority of the application PV 59 711 from April 29, 1966 in! France is occupied.

Thin magnetic layers are known for both storage and switching purposes. In connection with the Invention, only the memory arrays are of interest. There are essentially two storage principles in the literature described, once a single-layer arrangement in which only destructive reading is possible and an arrangement with two thin layers lying on top of each other, with which non-destructive reading is possible (Steinbuch "Taschenbuch of message processing ", Springer 1962, pp. 580 - 583) ·

Based on the last-mentioned arrangement, an electrically changeable matrix-shaped semi-fixed value memory has already been developed proposed in which each element consists of two superimposed individual thin layers, the storage layer and the reading layer, whose preferred directions are in the same direction and are parallel and in which the memory layer of each element has one bit and one word conductor and the reading layer of each element with one call and one

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a reading ladder is provided, with all reading ladder closed a single reading loop are connected in series and in the case of the bit-serial reading parallel to the reading conductors Inhibition conductors are provided and in which an electrically conductive intermediate layer is also applied between the two magnetic layers.

The invention is based on this proposal and the prior art mentioned.

Two ferromagnetic films, which are arranged one above the other and mutually influence each other magnetically, are provided. In one of the two films, row and column conductors define individual memory cells at their crossing points, in which a binary 0 or a binary 1 can be written, with each binary value being one of the two stable ones Corresponds to directions of the magnetization vector of the skins. As a result of the magnetostatic effect of one layer on the other, an equal number of cells is defined in the second layer, the direction of the magnetization vector of which differs from the direction of the magnetization vector of the first layer is affected. The second layer is also provided with ladders that allow the interrogation and reading of the Enable cells of the second film. After the query or. During the reading process, the magnetization vectors of the cells of the second layer rotate back to their initial position returns from the first film under the influence of the remanent magnetization, assuming that the magnetization the first layer is not affected during the reading process.

As already defined above, the first layer is called aet the storage layer and the second layer the reading layer.

With the known memories it was previously only possible to read the information word by word, i.e. bit-parallel. At a

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Such a memory, however, is the expenditure on control electronics quite high. It is also sometimes desirable to have a memory to be able to read bit-serial.

The invention provides an improved thin film semi-fixed value memory which can be read bit-serial.

The invention is characterized in that the Inhibitionsleiter parallel to the individual conductors of the read loop as a linear conductor, and that the L _eS a Kreusungspunktes s two pulses in succession to the associated query conductor and in each case before the trailing edge of the pulses of the first pulse to all except the associated inhibition conductor, and with the second pulse on all inhibition conductor pulses are given and that a circuit is provided for comparing the read signals occurring on the read conductor at the leading edge of the two interrogation pulses.

The invention thus differs from the older proposal essentially in that the inhibition ladder are not meander-shaped and are interrogated with two consecutive pulses.

The invention will now be explained in more detail with reference to the figures, for example. Show it:

1 shows a section through a storage level,

2 shows a perspective illustration of the storage level and the associated lines,

3 shows the different positions of the magnetization vector a memory cell,

Fig. 4- the relative positions of the inhibition and Interrogation pulses,

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5 shows an arrangement with two storage levels,

6 shows another arrangement of the conductors on the reading layer.

1 shows in section the various layers which belong to a storage plane according to the invention. In this figure, 1 is a conductive layer of thickness d, for example made of copper, on which a first ferromagnetic thin film 2 of uniaxial anisotropy, the anisotropy of which is H _1n -; and its starting

very
field strength / is large, was applied. The heavy direction of the thin film 2 lies in the direction of the dashed line 6, while the light direction is perpendicular to the heavy direction 6. The easy direction is not shown in FIG. 1. On the other side of the carrier plate 1, a magnetic thin film 3 is applied, which has a uniaxial anisotropy and whose anisotropy field strength Εγγ is smaller than the anisotropy _{field strength Hr n} ^ of the thin film 2. The film 3 is applied so that the easy and difficult directions of this film are parallel to the easy and difficult directions of the thin film 2. The difficult direction is indicated by the dashed line 5.

Ferromagnetic thin films with different ^{Anisotropiefeldst:} strengths one obtains' in various ways. The thickness of the thin film is particularly important. In the 3eis .iel described, the thin film 2 is an iron - i. "Ickel-Ilobalt -" - errierunr, which is a few thousand angstroms thick. The thin film 3 consists of iron-nickel with a thickness of several hundred angstroms. The thickness d of the carrier plate 1 is a few tens of millimeters.

In FIG. 2, the eir.en Full 'rAiren memory is a perspective view, one finlet lie three layers 1,2 and 3 of Fig. <Again. Die -x the ferromagnetic]! ' Thin films 2 and 3 - with ur-axial anisotropy run parallel. The dashed line IC indicates the axes.

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On the lower thin film 2, straight conductors M1, M2, L 3 and M4 · parallel to the easy direction and parallel to each other are deposited. Straight conductors 01, C2 and 03 are perpendicular to conductors M1 ″ to IvI4 and thus parallel to the heavy direction of the two thin films. These conductors are normally designed as printed circuits. The seven conductors M1 to k4 and 01 to 03 are at their crossing points twelve memory cells definiert.Diese have in the absence of an external field h two states of stable equilibrium of its magnetization vector L (Fig. 3) · These two equilibrium states, the two possible directions of the magnetization vector twelve memory cells. parallel to the light direction, it ie opposite to each other. when storing The one direction of the diagnostic vector is assigned to the binary 1. Such magnetic thin-film memories are described in large numbers in the literature, but it is useful to briefly describe the mode of operation of such a memory, in particular the writing process.

It is known that when a piece of magnetic material with uniaxial anisotropy is brought into a magnetic field with the field strength H (Fig. 3), the direction of which is a »prong 1 a to the easy direction δ. the lagging vector L, which was originally in the position LI, rotates through an angle b which is given by the following equation:

sin 2b 2H

sin (a - b)

In this equation, Hj- means the anisotropy field strength of the thin film, which will be explained below. It is also known that according to the value of the applied Field H is either the rotation of the magnetization vector

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is reversible or irreversible, Ί.η. that the vector after Shutdown of the field H returns to its original position or not. The curve for the theoretical limit of the Field strength H is an astroid whose reversal points are on the easy and heavy axes, with the value on the The abscissa is the value of the anisotropy strength H- .. of the 'material indicates. If the end of the field vector H lies within the astroids, then the rotation is reversible and it takes place as with the so-called coherent rotation. The processes are actually much more involved, for the following explanation is the explanation given above; however sufficient.

However, values of the magnetic field strength running in the direction of the easy axis are observed which are smaller than Ey and greater than 4 ^eil i value H. The value H corresponds to a field strength, which is called the starting field strength, at which the rotation is irreversible and runs like the so-called .Vand shift. In the case of certain thin layers, the so-called inverted layers, irreversible rotation as a result of wall displacement is observed even with magnetic field strengths greater than H ^. are.

If a binary 1 is written v / ground, by determining the location of the corresponding LH Lagnetisierungsvektors, a field E ^ in the direction of the hard axis D .rke Hg is first treated with a field strength greater than the Anisotropiefeldst ^:: applied. The lagging vector L is then located in the direction of the difficult direction D. A field H * is then applied in the direction of the easy direction A. The magnetization vector II then assumes the position I.I2. The field H- is then switched off, whereby the magnetization vector is in the position & A parallel to the field H ^. and got in the same direction. If the latter field is switched off, the vector Li remains in the position I./1, which is a stable one

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Location is. It should be noted that the direction of the Field H. determines the binary value to be written, while field H «can have one or the other direction.

According to Fig. 2, the magnetic fields H ^ by the Heads M1 to M4 generated to the otromimpulse with appropriate Amplitude and length can be applied. The magnetic fields H. are generated by the conductors 01 to 03 to which also current pulses of suitable amplitude and length The polarity of the last-mentioned pulses determines whether a binary 0 or a binary 1 is written will. After this determination, conductors 01 to 03 are grounded Bit conductor and the conductors L / 1 to i are called "i4" Vorleiter there each of them enables a binary word to be written, which in the example of Fig. 2 contains three bits.

The twelve memory cells defined by the crossing points of the word and bit lines are actually just as many small magnets, the magnetization of which has the same direction as the magnetization direction defined above. As a result of this magnetization, according to the laws of magnetostatics, a permanent Lagnetfeld H. parallel to the light direction of this film, but in the opposite direction to that of the magnetization vector of the thin film 2 is generated in the ferromagnetic thin film 3. This is shown in FIG. 1. If, for example, the Lagnetisierungsvektcr a memory cell 8 of the thin film 2 with respect to the Z> eic .en level is directed from front to back, as indicated by the symbol labeled 7, then the field H ^, which is in the corresponding memory cell 9 of the thin film 1 is induced, directed from the back to the front, as indicated by the reference numeral 4-indicated.

In the following description the following are referred to as: denotes such memory cells that are on the thin film 2 and

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are arranged one above the other on the thin film 3, such as, for example, the cells 8 and 9 towards -li'ig. 1. The twelve cells of the thin film 2 are thus assigned to twelve cells on the thin film 3 which are exposed to the field strengths H. which originate from the parts of the thin film 2. These fields H. are oriented parallel to the light seal, but the . permanent magnetization of the cells of the thin film 2 opposite to the magnetization vectors of the cells of the thin film 3, the so-called reading cells have not accepted all the direction of the field IL It is assumed here, as £ induced ^Feldstr: RLRE H. small and in particular smaller. than the anisotropy field strength ELy of the thin film 3, so that the magnetization vectors can only adjust themselves in the direction of the induced field if they had this direction before. a field is applied via the conductors I- to I ^ parallel to the heavy direction, the field strength of which together with the field strength H. is sufficient to allow an irreversible rotation of the magnetization vector of all cells, that is, a rotation that is greater than the isotrophic strength H _{T <} -y. This magnetic field is then switched off and it was explained above in connection with FIG. 3 that the lagging vector is now set in accordance with the direction d = s of field H. After this process, the agnetization vectors of all waves in the thin film 3 have a direction which is opposite to the direction of the cells of the thin film 2 and in this way they identify the bits written in the memory cells. In the case of the fiction. On the other hand, special measures must be taken, as will be explained below in connection with the reading process, in order to bring all cells of the level into the same state before reading.

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The only condition that the field strength H. at a given value of the field strength, which is in the direction of the severe direction should be sufficient, is that it must be greater than a minimum value H. This luinimal value depends on the one hand the maximum angular difference between the easy axes, caused by the conductors of the reading layer and the easy axes of the memory cell of this layer and on the other hand from the maximum angular difference between the easy directions of the associated cells of the both layers.

.After a current pulse on one of the interrogation conductors, e.g. I., the magnetization vector of each of the memory cells that are assigned to this sense conductor is placed in the one or another direction of the easy axis, according to the binary information, which is located in the corresponding cell of the storage film.

On the other hand, if you give a current pulse to the inhibition conductors E1, E2 and E3, which are arranged above the bit conductors 01, 02 and 03 and thus parallel to the difficult direction, before the end of the current pulse on the interrogation conductor I., then the new field is Hin in the direction the easy axis directed and ert be // is such that when the pulse stops in his direction the magnetization vector which adjusts to the conductor 1 ^, cells connected in this ■ ^u pus. Part B of the pulse trains 1 '^ »^ Ί» ^' p and S ';, after ^' ig shows the times at which the impulses are given to the interrogation conductor and the inhibition conductor. 4. The-I- I 'are the query pulses and E ¹ the inhibition pulses. In order to achieve that the setting of the magnetization vector of the cells associated with the conductor I ^ is independent of the direction of the field H ^ which is caused by the corresponding cells of the storage film, it is necessary that the field strength% _n that is generated by the Ladders E ^, Ep and E-, evoked, at least equal

H, + H is.
in the

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IS3 / Reg. 3639 - 10 -

This increased adjustment of the magnetization vector can be in one or the other direction of the easy axis but, as will be explained further below, it must be the same for all cells of a level. In the further description it is assumed that the boosted setting corresponds to a binary 1. A cell described in the Wise set is referred to as the inhibited cell. Assuming that all cells assigned to the call line I ^ belong, were previously inhibited, a further current pulse is now given to the call conductor I., whereby all magnetization vectors of the assigned cells from the direction assigned to binary 1 in the direction of the resultant the fields H. and H. arrive. According to the relative values of fields H. and H., it is assumed that the magnetization vector is directed in the direction of the heavy axis. This change in direction of magnetization is recognized by a read conductor L (Fig. 2), the individual branches of which run parallel to the heavy axis. Each of the memory cells of which it is assumed that they are identical to a first approximation, then delivers to the part of the reading conductor, the it is assigned to the same read signal v1. However, since the individual branches of the read line are connected in series, these signals cancel each other out and the resulting read signal is 0 if the number of branches is even and v1 when the number of branches is odd. However, since the memory cells are not all identical and accordingly the signals v1, it follows that the resulting Read signal is about V in both cases. The exact calculation of the signal V takes place below.

Before the termination of this interrogation pulse, as explained above, an inhibition pulse is applied to all inhibition conductors, except that to which the cell to be read is assigned, for example the conductor E., if the cell to be read

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ISE / Beg. 3659 - 11 -

at the point of intersection of the ladder I ^, and E. Daini't get all cells of the conductor 1 ^, except the cell (1 ^, S ^), back to the 1-state and are inhibited again in this way «The cell (1 ^, E ^) gets into the state that by the field H., which is caused by the corresponding cell of the storage film, was imprinted.

If a new impulse now reaches the call conductor I., a signal V1 - V results if the cell (I ^ ₁ E.) is in the 1 state, since all cells belonging to the conductor I ^ are in the 1 state as before are. On the other hand, this read signal has a fourth Vo >> V - v1 + vo, where vo is denoted the signal that results from a change in the magnetization vector when the cell (1 ^, E ^) is in the 0 state, and where this signal is equal in magnitude and opposite in sign to v1.

If you read the cell (1 ^, Ep), an even-numbered cell, just like the odd cell (1 ^, E ^), then yields it can be seen from the above that the first read signal V is equal, as is the second, and the V / ert V1 = V, if the cell (Ι ^, Ε ^) is in the 1 state. Is located the cell (1 ^, Ep) in O-state, the second is oirrn & l V 'ο »V + vo - v1.

To determine the state in which the cell (Ι ^, - Ξ ^, it is therefore sufficient if π: εη is the amplitude of the signal V during the first interrogation pulse with aer Amplitude of the oil V1, Vo or Vo wKhrer.i of the second. Compares the interrogation pulse. The electronic circuit for this comparison contained, for example: a balanced amplifier, whose inputs are connected to the - ^ eselleiter L, namely one directly and the other via a delay line, whose time constant equals the distance between the two -i-esesi ^ r.ale is, i.e. the two Abfreceimpulse. To compare the

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ISS / Heg. 3639 - 12 -

The balanced amplifier only needs read signals from a cell be sensitively controlled up to the rising edge of the second interrogation pulse.

Before the end of this second interrogation pulse, a pulse is given to all inhibition conductors E ^ to E, so that the _{cells assigned to interrogation conductor I 2} are inhibited again and are thus prepared for the following reading processes:

In summary, therefore runs _# a read cycle for the previously inhibited cell (1 ^ E ^.) In two steps: in the first step are current pulses to the polling wire I ^ and the Inhibitionsleiter E ~ and 2 are given. The timing of these pulses is in the diagrams I ¹ and E ¹ according to i ⁿ ig. 4- shown. Only the signal V on the read conductor L, which occurs on the leading edge of the interrogation pulse, is taken into account. In the second step, the same current pulses as in the first step are applied to the conductor I ^ and to all inhibition conductors E, -, Ep and E, and only the signal V1 or Vo occurring on the - ^ eseleiter L at the leading edge of the interrogation pulse considered.

In Fig. 4 different curves show how that of the ^ eIIe (1 ^ ,, E,.) Takes place, which previously as well as the cells (1 ^, J.0 and (1 ^, E ₂ ) by the inhibition pulses, which are shown in part B. The reading signals appearing on the reading conductor L are represented by the curve L ¹ and it can be seen that the signal corresponding to the first queryixp "; ls on the. J.rlich amplitude and polarity is untestimmt for this reason it has been shown in phantom, the part C of the curve L ¹ corresponds to the x-esesignel that r.an ^erhl:... (. 1, e) according to if the cell is a binary 1 contains Ir -. "iesem case both oisrnele the amplitude v1, the part ie the number of Inhibitionsleiter is odd and of the same polarity, for example positive D of the curve L ¹ corresponds to the i-esesiq-dimensional obtained..

0098 Ib / 1494 ^ AO csaiMAL

ISE / Reg. 3639 - 13 -

if the ^ eIIe (1 ^, E.,) contains a binary O. That the Interrogation pulse D1 corresponding first signal has, as in the case of the binary 1, a positive amplitude v1, while the second signal appearing at pulse D2 has a negative amplitude vo.

As already stated, the read cycle was given the assumption described that the cell in question in the previous read cycle for this or another cell that was with coupled to the same query conductor has been inhibited. This previous inhibition is not completely guaranteed, when the cells are queried for the first time after the memory film has been written. For this reason, is it is provided that every write operation in the storage layer is followed by an inhibition of all cells of the read layer. In the Description of the read cycle it was assumed that all memory cells that are assigned to a sense conductor, are identical and that each of the cells emits an identical read signal v1 or vo.

This assumption is correct when the memory cells cover only a small area of a thin film. However, it no longer applies if the entire film area is occupied by storage cells. In this case, however, a short calculation shows that the operation of the memory is not affected. Assuming that 2n cells are assigned to an interrogation conductor, one needs a read conductor with two 2n branches. If Vp * denotes the algebraic value of the signal that occurs when the cell with ordinal number 2i is ₁ and V ^ 1 denotes the algebraic value of the signal that occurs when the cell with ordinal number 2i is 0, then is the read signal V, which is obtained in the first part of the read cycle, given by the sum formula

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ISE / Reg. 3639 - 14

During the second part of the read cycle, the read signal V1 »V is obtained if the scanned cell contains a binary 1 and the read signal:

if the queried cell contains a binary O and is an even number is or a read signal:

i = η

/ 1 1 \ 1 ο

^(v 2i-1 - ^V 2i ^} - ^V 2i-1 ^{+ V} 2i-1

if 'the queried cell / is an even number.

The relative difference between the two successive read signals of a read cycle is thus:

in the case of a binary 1 and:

_oaer

in the case of a binary O, where j is the ordinal number of the queried cell is.

In this way the same results are obtained as with > the simplified assumptions that were used during the description of the reading process. Only the read signals are not exactly the same from cell to cell.

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ISE / Reg. 3639-15-152A785

The carrier plate 1 serves to hold the cells of a ferromagnetic Film against the magnetic produced by the current pulses on the conductors dta other magnetic film unfortunately shield. Because these magnetic fields change over time the conductive carrier plate is a magnetic shield for these fields. For the static magnetic fields, especially for the field H ^ is the shielding Carrier plate 1 not effective. However, the variable fields may have static components against which protection is required is, in particular with regard to the static components caused by the currents in the reading film in the storage film 2 The thin film 2 therefore has a very large anisotropy field strength and a very large dtartfeid strength, dit make it insensitive to a large static component. The smaller of the two field strengths is taken into account . The carrier plate 1 also serves as a common return conductor for all conductors.

The electronics associated with the conductors are not shown in FIG. 2 shown, as this is similar to that of thin-film memories with destructive reading. The circuits that make up the interrogation and inhibition ladders are also not shown as they are similar to the writing circles. The ones they delivered Pulses are shown in FIG.

Since with the arrangement according to the invention, the bits of a memory plane can be read one after the other, it is also possible simultaneously reading ρ cells in a memory with ρ memory levels according to FIG. 2, the ρ being read simultaneously Cells have the same coordinate in each level. Such a memory contains e.g. two 2-levels G and F, each with twelve cells, as shown in FIG. The corresponding interrogation and inhibition conductors are connected in series. The direction of flow In these ladders, each level is reversed to the next and the same applies to those through them generated magnetic fields. However, as already mentioned, this is

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■ Regarding the query fields of no importance, since these can have one direction or the other with respect to the heavy axis. With regard to the inhibition fields which cause the increased setting of the memory cells, however, it should be noted that this setting corresponds to the 1 state in a first memory plane and to the 0 state in a second memory plane, so that the corresponding read signals of the two planes are of opposite polarity to have. In addition, in the second level the second signal of a read cycle is the same as the first in the case of a binary 0 and of reversed polarity in the case of a binary 1, ie the relationships are reversed with respect to the first level. To avoid this disadvantage, it is sufficient to reverse the comparison criteria of the two successive read signals of the second level with respect to the first the writing in the memory cells of the memory film of each memory level must be carried out simultaneously for all memory cells belonging to a word line (M1 to M4-), while the ρ bit that is to be written must be written simultaneously in ρ memory cells, Each of the ρ memory cells is assigned to a location conductor of each storage level. It is therefore necessary to provide an auxiliary storage device in which all bits belonging to the corresponding word conductors are written. Eicher, desfea ^ b must contain as many lines as memory cells belong to ... a gate ladder ren (e.g. L.4, Fig. 5), each file ,. _r contains p cores, ie as many cores as there are memory levels. For the memory according to Fig. 5, the auxiliary memory must therefore contain three / lines of two cores each. The conductors of this auxiliary storage device and the control electronics must be designed in such a way that the ρ cores of a row can be written to at the same time and all cores of a column can be read at the same time, the cores of this column belonging to a "nursery manager, e.g. a14 To write or completely rewrite a memory in accordance with the

. "■ ■■■■■■ '■'." '. ■ ■■■' ■■: ■. - - BAD ORHsJMAL

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ν v:; -17-

ISE / Eeg. 3659 - 17 -

Invention, the bits that are in the memory cells, the corresponding word lines belong to each other, first in written to the auxiliary memory and then to the Main memory transferred, with the bits in each column interrelated are written into the memory elements of the corresponding word lines.

Amending of bits, for example, for the .Modification Portes, the bit at the Crossroads. ;; spünkt the conductor 14 and E1 (S ¹ Ig. 5) are the Information.der memory elements to the interrogation conductors I ₁ is. belong, transferred word by word to an auxiliary memory after non-destructive reading and then the ./location, which is located in a line of the auxiliary memory, is changed. Finally, the information "is transferred from the auxiliary memory" to the main memory, as described above for complete writing.

The storage film 2 with uniaxial anisotropy can by a isotropic thin film, whose coercive Field strength significantly higher than the anisotropy field strength *% - y of the reading film and its residual magnetization in the Direction of the easy ^ eyse of the reading film is directed. In the storage film of the various storage levels is shown in in this case preferably written by current coincidence as in the case of ferrite core oeichern. The selection pulses and the current pulse β must then be chosen appropriately. The lines that Columns and the write conductors are at the storage layer se arranged one above the other and the polarities of the current pulses, that are placed on this ladder must be chosen so that the field strengths evoked by the selection leaders will add up while the field drawn by the write conductor is caused, depending on the bit to be written is added to or subtracted from the selection field. To this Mode can also be written if the storage film has ujaiaxial anisotropy.

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ISS / Seg. 3639 - 18 -

There are also magnetic core memories in which each bit is written into two memory cells located next to one another. Such memories are referred to as two cores per bit. Everyone is there. Branch of the conductor L is doubled and each of the new branches is assigned to a magnetic spot of the bit, as shown in FIG. This storage method can also be applied to the semi-read-only memory according to the invention. In this case, writing takes place in such a way that the magnetization vectors of the two magnetic spots of a bit have opposite directions; the same applies to the magnetization vectors of the corresponding magnetic spots of the reading film. The various branches of the reading ladder L run parallel to the difficult direction, just like the inhibition ladder E ^, E ¹ ^, Et, E'e and Eg, E'g, the number of which is equal to the number of branches of the reading ladder. The interrogation conductors run parallel to the easy sighting and the magnetic spots of a bit are assigned to the same interrogation conductor. Only one interrogation conductor and the like is shown in FIG. 6. In this figure, the magnetic spots of the reading film are designated as pike corners t or t ¹ . Within these rectangles, the arrows indicate the direction of the magnetization vector and it is assumed that the 1 state corresponds to the arrow in the linear spot t ^. For 3s it is also assumed that cell 6 ^ »V ^.) Contains a binary 1, while cell (t, -j.t'v) contains a binary one. This "memory is read in exactly the same" way as the memory according to FIG.

If all magnetic spots belonging to an interrogation conductor I have been inhibited before, the magnetization vectors of these magnetic spots are the same. Directional direction according to the 1-state, as represented by the cell (t _c , t ^r , -) «The first interrogation pulse causes a signal f on the line L according to the equation:

IT « >·" t Cv ^ - v ^{> 1} )

i »1 ^±

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ISE / Reg. 3639 - 19 -

'■■ "' ^: -Λ '■' ■■■ '

in the γ. the read signal for the 1 state of the magnetic spot t of the cell i, ν% the read signal at the "1 state of the magnetic spot V of the cell i and η the number of cells that are to einöm query ladder belong, mean.

3 is the ordinal number of the queried cell during the second Half of the query process, the signal on the read line is:

¹ > + v ' ¹ -

wina there is a "1 ¹¹ in cell j, i« ή _ή α _η λ

when there is an "O" in rope j.

The relative difference between the two signals being compared

- V;

i a "1" and

I 'y "' on a" 1 "

» with an "O" or

v ' ¹ -v ¹ ^

,. «■ - .. ■,. ,,, i_ assuming that V = V.

Dtft signals resulting from the comparison have the opposite polarity, depending on whether a "1" or "la""ö * ^{1 is} read. In a memory with one magnet clip per bit, the same signals are at a "1", and positive or negative for an ¹¹ O ". The memory with two

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ISE / Reg. 3639 - 20 -

Magnetic spots per 'bit is more useful for this reason, since the Setting the comparison circuit is less critical. In addition, the double read conductor eliminates the interference signals that caused by the interrogation fields are reduced to a minimum, namely, these signals stand out in two related ones Share the reading ladder on each other.

Build memories with several levels with two magnetic spots per bit, then it is also necessary to use the comparison criterion for successive signals of a read cycle to reverse.

IS f;.? -:

BAD 0RKS1HAL

3 claims
3 31st drawing, 6 ϊ

^x ■ ..- .. ■■.-21-

009815/149 ^

Claims (3)

ISE / Reg. 3659-21 claims 1. Electrically, changeable matrix-shaped semi-read-only memory, / in which each element consists of two superimposed individual thin magnetic layers, the storage layer and the reading layer, whose preferred directions are in the same direction and parallel and in which the memory layer of each element has one bit and one Word ladder, and the. Reading layer of each element is provided with one call and one reading conductor, all reading conductors being connected in series to form a single reading loop, and in which inhibition conductors are provided parallel to the reading conductors for bit-serial reading and in which there is also an electrically conductive intermediate layer between the two magnetic layers is applied, characterized in that the inhibition conductors (E1 ... E3) run parallel to the individual conductors of the reading loop (L) as a straight conductor and that for reading a crossing point, two pulses successively on the associated interrogation conductor (I) and in front of the Trailing edge of the pulses are given to all except the associated inhibition conductor at the first pulse, and to all inhibition conductor pulses at the second pulse and that a circuit is provided for comparing the read signals occurring on the reading conductor (L) at the leading edge of the two interrogation pulses. Me / Sd 4/25/67 ..- ■ ...: -.- _ ₂₂ _ 00 98157U94 ,; Y 'O c 0 Ιοί / Reg. 5639 - 22 - 2. Storage of ρ memory arrays according ioispruch 1, characterized in that the bits of a '"each map to the same location each plane are accommodated and that the ρ bits are interrogated in parallel upon reading and that the mutually corresponding query and Inhibitionsleiter the levels ρ are connected in series. 3. Memory according to -mspruch 1 and 2, characterized in that the ^ storage layer (2) is isotropic and has a large coercive force, and that the direction of the remanent magnetization of the storage layer is parallel to the easy axis of the reading layer.