Patent GB-961596-A (GB)
Title: Magnetic plate memory system
IPC: G11C7/02
Filed: 1961-07-31
Abstract: 961,596. Magnetic storage apparatus. RADIO CORPORATION OF AMERICA. July 31, 1961 [Aug. 26, 1960], No. 27759/61. Heading H3B. Each plane of a random access magnetic store comprises a single ferrite sheet having a plurality of aperture pairs arranged in rows and columns, each aperture pair providing storage for a single information bit. The arrangement improves the magnetic isolation between adjacent storage regions of a ferrite plate since the fluxes about an aperture pair are restricted in magnitude and depth of penetration by saturation of the region between the two apertures. Higher amplitude switching currents may therefore be used. As shown in Fig. 2, each plane comprises an apertured plate 30, 31 provided with aperture pairs such as 33, 34. Aligned apertures through the planes are threaded by a looped readwrite drive line C1R1, C2R1 with the loops extending in opposite directions through adjacent aperture pairs in the rows. All the apertures in a plane are threaded by a digit winding 38 which may be a printed conductor, and the resulting aperture wiring is such that the digit winding passes through both apertures of a pair in the same sense, while the drive line passes through one aperture in the same sense and through the other aperture in the opposite sense. To write a binary one in a selected pair of apertures, the associated read-write drive line is negatively pulsed in coincidence with a negative pulse in winding 38 from a digit drive 40. The flux conditions then obtained in the aperture pair are a saturating anticlockwise flux about aperture 33 and substantially zero flux about aperture 34. Coincident drive pulses are also used to write a binary zero, but in this case the digit winding 38 is positively pulsed so that substantially zero flux is obtained about aperture 33 and a clockwise saturating flux is established about aperture 34. Read out is effected by positively pulsing the read-write drive line, and an appropriate positive or negative pulse, depending on the digit stored, is induced in winding 38 and detected by a sense amplifier 42. An alternative embodiment is shown in Fig. 8 in which the read-write drive lines are each replaced by a pair of conductors X, Y, threading pairs of apertures 53, 54 in rows and columns respectively. The digit drive winding is also modified so that one digit winding 56 threads all the upper apertures of a pair and a second digit winding 58 threads all the lower apertures. To write a binary one in a selected aperture pair, the associated X and Y conductors are negatively pulsed at the same time as a positive pulse is applied to digit drive winding 56 from a digit drive source 60. This establishes a clockwise flux around the lower aperture 54 only, the flux about the upper aperture 53 being substantially zero due to the opposing digit drive pulse in winding 56. As the X and Y conductors are pulsed by currents of " half write " value the remaining aperture pairs in the row are unaffected. Similarly, with a positive pulse in winding 58 from a zero digit drive source 62, a binary zero is registered by establishing an anticlockwise flux about aperture 53. Read out is effected by positively pulsing the X and Y conductors in coincidence, and a pulse is induced in winding 56 or 58, depending on whether a binary one or zero is stored. The identity of the digit read out is detected by a sense amplifier 64.