DE1050809B - Core memory bias - Google Patents

Description

GERMAN

The invention relates to a method for operating value memories made up of bistable magnetic cores are constructed. The cores are subjected to constant DC magnetization.

Such cores consist of a material with an approximately rectangular hysteresis loop. After magnetization to saturation in one direction or the other, a remanent flux remains in one direction or the other for any length of time. B. can be used to represent the values "1" or "0". Only a field strength greater than the coercive force can cause the transition from one state to the other.

Cores made of the same material are also used as switches or impulses; one winding of the core supplies a voltage surge during the remagnetization from one remanence state to the other, the z. B. can be used to drive a core memory.

It is known to provide such cores used as switches with a direct current bias, which brings the material to saturation. The purpose is to automatically return the core to its original position, after being brought into the second state by an impulse. This DC bias must exceed the amount of coercive force, otherwise the used as a switch Kern would not return to the state necessary for the next switching operation. That too known impulse bias of cores working as switches to saturation is for as memory The cores used cannot be used, as the level of the interfering signals generated in this way is not acceptable for the core memory were.

It has also already been proposed that all cores of a core memory be powered by a direct current up to To magnetize saturation with the aim of clearing the memory between two work cycles.

The inventive method, the storage of, for example, numerical values serving magnetic cores of a constant Suspending DC magnetization has a different purpose. The hysteresis loop more available Core materials deviate from the desired rectangular shape. In the drawing, a dashed line is an ideal Rectangular and drawn out the hysteresis loop of a practically available material is shown. The deviation of the rectangular shape causes that field strengths smaller than the coercive force are capable of flux changes to generate in the core. With the usual arrangement of the memory cores on the intersection points The magnetization reversal usually takes place through a rectangular coordinate network in the manner of a matrix coincident currents acting in the row and column direction of the matrix. Because the cumulative effect of these currents cause the saturation of the core lying on the intersection of the selected row and column Core memory bias

Applicant:

IBM Germany

International office machines

Society. mbH,
Sindelfingen (Württ.), Tübinger Allee 49

Dr. Karl Ganzhorn, Dr.-Ing. Theodor Einsele,

Sindelfingen (Württ.);

and Hans Bornhauser, Böblingen (Württ.),

have been named as inventors

half the field strength to which the unselected nuclei of the current-carrying row and column are exposed are more or less in the kink of the hysteresis loop.

It is arbitrarily assumed that the point of intersection of the hysteresis loop with the positive branch of the ordinate (above the abscissa) is used to represent the value one, and the point of intersection with the negative branch of the ordinate is used to represent the value zero. These points are designated E and N in the drawing.

The writing process, that is, the entry of the value one in a nucleus, brings it with the current J from point N to point P ; the cores of the selected rows and columns receive only half the field strength and reach point Q *. After the impulses have decayed, the selected nucleus goes from P to E; however, the semi-magnetized nuclei do not return to N , but to points on the ordinate axis between N and the start of the coordinates. Repeated action of half-pulses on the same core, which are unavoidable when operating the core memory, can if not destroy the memory value zero, then at least impair it to such an extent that a subsequent reading (removal) process, which brings this core to point P *, incorrectly delivers a signal. In a memory made up of many cores, this results in a high interference voltage that covers the useful signal.

According to the invention all the cores of the memory in the reading direction subjected to a permanent magnetization by a constant direct current I ₀ (s. Drawing), which brings them to the designated with "1" and "0" points of the hysteresis loop, depending on the registered memory value and the field strength H ₀ generated. A write operation starting from point »0« to store the value »l«, which determines the field strength of point P

809 750/214

now requires the total magnetizing current Is. Half of its value is only reached by point Q outside the bend, the risk of fault value formation is eliminated. At the same time, the tolerance within which the 'pulse amplitudes may fluctuate' without endangering operational safety is increased. The reading field strength, which with the current Ij ₁ must bring the nucleus from point "1" to point P * , is as large as half the writing field strength and is generated with only one coordinate winding; the signal voltage appears on the line of the other coordinate.

The peak value of the reading voltage of a core at a reading field strength Hj _{1 is} greater than 1.5 times the coercive force H _c

^ ₀ = COnSt (Fi - H ₀ )

without bias. With the premagnetization H ₀ one obtains

Uh ₀ = const (H _L + H ₀ - H ₀ ).

The switching time Ts of a core, e.g. B. from point E to point P *, without bias

const

Ts (O) =

when applying the constant field strength H ₀ , it is calculated as

T (JT \ - ^const

■ * «V" 0 / - JT ι ττ TT

■ "£ -f- Xl ₀ ■ - U ₀

The equations state that the signal voltage and the switching time are increased by means of the premagnetization can be shortened while maintaining the read pulse amplitude or the same signal amplitude and Switching tent with lower reading pulse amplitudes can be achieved;

On the other hand, especially when using

higher read pulse amplitudes (1 ^ ₁ in the drawing) low interference amplitudes, high signal voltages and

ίο short switching times with cores with a lower coercive force and realize a poorer rectangular shape.

Claims (3)

Patent claims: 1. Magnetisierungsvei drive for memory cores with an approximately rectangular hysteresis loop, thereby characterized in that all nuclei are continuously exposed to a constant field strength in the reading direction which is smaller than the coercive force. 2. The method according to claim 1, characterized. draws that the constant field strength is half as great is like the coercive force. 3. The method according to claims 1 and 2, characterized in that the reading process by a pulse is caused in only one coordinate direction of the core matrix arrangement. Considered publications:
French patent specification No. 1 095 967. 1 sheet of drawings 750/214 1. 59