Patent GB-1040851-A (GB)
Title: Improvements in or relating to memory systems
IPC: G11C11/12
Filed: 1963-04-23
Abstract: 1,040,851. Magnetic storage devices. AUTOMATIC ELECTRIC LABORATORIES Inc. April 23, 1963 [Nov. 23, 1962], No. 16032/63. Heading H1T. [Also in Divisions G4 and H3] In a magnetic memory comprising a storage element in the form of a magnetic conductor helically disposed about a non-magnetic conductor a D.C. source is connected to the non- magnetic conductor to provide a first magnetic field and a source of alternate polarity repetitive pulses is applied to an electrical conductor to provide a magnetic field coincident with and orthogonal to the first magnetic field. A memory system, Figs. 1, 2, has a plurality of twistors 9 arranged in M rows and N columns. Information is written into the bit locations on the twistors by applying coincident information pulses from drivers ICI to ICN and interrogation pulses from drivers PDI to PDm. The information current applied to the non-magnetic conductors is either positive or negative, Fig. 11, depending on whether a " 0 " or a " 1 " is to be written and lasts for five sets of interrogation pulses applied to the appropriate solenoid 8. The magnetic fields established by these pulses are orthogonal, conductive areas 7 located below the solenoids 8 acting as virtual solenoids to amplify the magnetic fields, and will progressively switch a portion of the magnetic conductor from one state to another for a length along the twistor that is greater than the width of the copper conductive area 7. As shown in Fig. 13 at the end of the first set of interrogate pulses regions A-A are placed in a set state and regions B to E on either side of the solenoid are only partially switched due to the exponential attenuation of the solenoid fields. The second set of interrogate pulses will set the regions B-B and only partially set the regions C to E and so on. To read out a word the twistors are connected to their respective sense amplifiers SAI to SAn and pulses are applied from the selected interrogation driver PDI to PDm to the corresponding word solenoid. The read pulse produces a field that tends to block or reverse the remanent state of the portion of the twistor forming the bit, assuming that the bit locations are in their set or " 1 " state, but only does so at the centre of the solenoid, Fig. 10 (not shown). The next reset pulse of the pulse train resets the bit to its set or " 1 " state. Output signals as shown in Fig. 11 are induced in the non-magnetic conductor, more flux being switched if a " 1 " is stored than if a " 0" is stored. In the two-twistor-per bit arrangement of Fig. 3 (not shown) in which the return line 10 of Figs. 1, 2 is replaced by a second twistor read-in and read-out operations are performed in the same manner as for the single twistor per bit arrangement of Figs. 1, 2, Fig. 7 (not shown). However, since the twistors are connected in series then during write-in operations one twistor will be set in one state and the other in the other state according to the polarity of the information signal. Thus during read-out, different output voltages will be induced in the respective non-magnetic conductors of the twistors and the output voltage applied to the sense amplifier SAI to SAn will be the difference in the voltages induced in the twistors. In Fig. 4 (not shown) a single twistor per bit is shown employing a plurality of twistors and a plurality of return conductors placed on a conductive sheet having a plurality of apertures therein, a printed circuit solenoid arrangement being placed over the arrangement. Figs. 5, 6 (not shown) are a double twistor per bit arrangement similar to that of Fig. 4. Figs. 7, 8, 9 (not shown) indicate how the solenoids may be arranged with respect to the twistors for cancelling out noise.