Patent GB-1010188-A (GB)
Title: Cryogenic switch
IPC: G11C11/44
Filed: 1962-08-03
Abstract: 1,010,188. Selective signalling. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 3, 1962 [Aug. 21, 1961], No. 29857/62. Heading G4H. [Also in Division H3] A superconductive selector switch or a repeater for increasing the number of energized channels in a branching system comprises a plurality of input circuits 511-514, Fig. 8, each consisting of two superconductive parallel paths 511C, 511D-514C, 514D, through which current may be selectively directed by a cryotron gate such as 514E, 514F in each path, one path in each parallel pair being coupled through a pattern of apertures 521A in a superconductive plate 521 to short-circuited superconductive turns 531, 541, 533, 542 inductively coupled to certain output circuit paths 551D, 552D, each output circuit 551, 552 consisting of two parallel superconductive paths 551C, 551D, 552C and 552D. When used as a switch currents must be induced in both short circuited turns associated with a single output circuit path for that path to become resistive, and since each short circuited turn has an extension 531A, 541A which forms an in-line cryotron in association with a different input superconductive path through a respective aperture the arrangement forms a group of AND gates, Fig. 7 (not shown). When the arrangement is used as a repeater, only one short circuited turn 932, 934, Fig. 11, is associated with a respective output circuit path 961D, 962D. In both the switch and repeater applications resetting is effected by causing the other parallel output path of each parallel pair to become resistive, and only single short-circuited turns are used, viz. 532, 534 in Fig. 8 and 931, 933 in Fig. 11. The reset control circuit consists of a superconductive pair of parallel paths 515C, 515D, Fig. 8, the conduction through which is controlled by cryotrons (not shown). For resetting the path 515D is made resistive, and the current through path 515C is coupled to the reset short circuited turn 532, 534 through apertures provided one for each output circuit. When resetting is effected only the output paths 551D, 552D are conductive. Subsequently the resetting signal is removed, and the input circuits are appropriately controlled so that selected output paths 551C, 552C become conductive. Each output path forms the control conductor of a cryotron such as 514E or 514F of a following stage. Application.-The switches and repeaters are used for the writing of a data bit or the reading of a superconductive memory array under the control of an address 128, Fig. 2, the arrangement being stated to provide more rapid operation as the various stages 201-207 of switches SW and repeaters REP may each have a different signal content which is passed from stage to stage as operation proceeds. The read or write instruction is applied from 126 and the data bit to be written is applied from 127, routing of the primary instruction through the various stages being controlled by the address 128. The number of outputs of a switch or repeater is denoted by the number in the interconnecting arrows. When the array is read the output is routed through superconductive OR gate stages 208-211 to a final output 199. Superconductive storage element.-One of two parallel superconductive paths S03, S04, Fig. 5, is respectively conductive when a " 1 " or a " 0" is stored, the other path being brought into the resistive state by the combination of a select signal in control conductor S23 and a " write 1 " or " write 0 " pulse in a respective control conductor S22, S32. The element is read out by applying a current to a control conductor S42. If a " 1 " is stored the combined current effect causes a gate conductor S41 in the output circuit to go resistive. If a "0" is stored the conductor S41 remains conductive. Construction of switch or repeater.-The superconductive plate 521 comprises two superconducting ground planes 586, 587, Fig. 10b, and a supporting body 588, the ground planes being used as return paths for the circuit currents. At each aperture position the adjacent short-circuited turn 512C is dipped as shown to improve the coupling with the conductor 421. Another detail of interest is the use of a return portion in each output circuit path (see Figs. 8 and 11) so that the path is coupled with the whole of the adjacent shortcircuited turn.