GB823075A - Magnetic memory apparatus - Google Patents

Abstract

823,075. Electric digital-data-storage apparatus. AUTOMATIC ELECTRIC LABORATORIES Inc. June 11, 1956 [July 19, 1955], No. 17974/56. Class 106 (1). A digital data storage device includes a storage medium comprising a non-magnetic member having a plurality of isolated magnetic elements embedded therein, relatively movable write-in means selectively energizable to induce magnetizations of a particular polarity in selected ones of said elements, and means for causing relative movement between the storage medium and read-out means. As shown, a non- magnetic circular disc 70 contains a number of magnetic elements 75 arranged in radial rows a1, a2, &c., and concentric circles W, X, Y, Z, all the elements being normally magnetized in one axial direction so as to repel permanent magnet armatures 93. The disc is rotatably mounted on a shaft 17 and is rotated in a counter-clockwise direction, as shown in Fig. 3, by an electromagnetically driven pawl-andratchet stepping mechanism, the rotary position being indicated by indicia 86. Four write-in heads 76W, 77X, 78Y, 79Z are in the form of electromagnets having polepieces 80 to 83 disposed on one side of the disc, four read-out devices being provided on the opposite side of the disc, the read-out devices comprising permanent magnet armatures 93 and normally open contacts 96 arranged on contact spring sets 87 to 90. An item of information is written into the store in a four-element binary code, the four magnetic elements 75 corresponding to one item being arranged one in each circle of elements in a spiral group such as on the spiral 100, Fig. 6. When the disc is in its initial rotary position the spirally-arranged write-in heads are selectively energized to change the magnetization polarity of the four elements associated therewith in accordance with the coded representation of the item of information to be stored. The disc is then stepped on by one and the next item of information is stored. In this way in a complete revolution of the disc a total number of items of information equal to the number of radial rows of elements 75 may be stored. The energizing circuit for the electromagnets 76W to 79Z are now opened and on a subsequent complete revolution of the disc, the information stored therein may be read out. When the first spiral group of elements 75 appears under the similarly arranged read-out armatures 93, the armatures associated with the reversed elements only will be attracted thereto to close contacts 96. On subsequent advancement of the disc by one position by the stepping mechanism, a new group of elements 75 will be brought into association with the armatures 93. In this way all the information stored in the disc may be read out. A group of elements which have been read may be cleared when advanced into association with the electromagnets 76W to 79Z by passing currents of opposite polarity to the writing currents through the electromagnets. Specification 805,599, [Group XXXIX], is referred to.