GB827310A - Improvements in digital electric signal selection apparatus - Google Patents

Abstract

827,310. Electric digital-data-storage apparatus. DIRKS, G. Dec. 18, 1957 [Dec. 19, 1956], No. 38635/56. Class 106 (1). Signal selection apparatus adapted to be operated by a serial signal train consisting of groups of discrete signals separated by time intervals, includes normally inoperative detection means which are switched to operative condition on the occurrence of a signal and revert to inoperative condition after a time greater than the interval between successive signals within a group but less than the interval between signals of successive groups, and means for deriving a pulse from the detection means at each reversion to the inoperative condition, which pulses operate a control circuit to make effective in turn at least two signal gating circuits to which the signal train is applied. The invention is applied to the digital-data-storage apparatus described in Specification 820,115 and much of the description is substantially similar. The invention concerns the means for detecting and responding to the spaces between the groups of pulses in each unit of information. Representation of data.-As in Specification 820,115 each unit of information consists of a number of groups of pulses, the first pulse in each group being used for synchronizing purposes. The remaining pulses in each group represent the following information: 100<SP>1-3</SP>, Fig. 2, = number of the storage track to which data is to be sent; 103<SP>1-5</SP> = the side of the disc to be selected from a plurality of storage discs available; 104 = the precise section of the storage track on which the data represented by groups 105, 106, &c., is to be entered. Each item of the address set out above is stored in a separate counting tube under the control of a device which is the subject of the present invention. Utilization of address signals from tape.-In the manner described in Specification 820,115 series of pulses corresponding with the signals read from the tape appear on a line 118<SP>1</SP>, Fig. 11. The first pulse of each group sets a bistable trigger circuit 225 which opens a gate 117 to allow subsequent pulses of the group to pass to a counting-tube register; also the first pulse changes over another bi-stable trigger circuit 220. If it is changed to the R.H. state, for example, a gate 222 is opened and a monostable flip-flop 224 is set in a state from which it will automatically return in approximately 1¢ digit periods. Before this occurs, however, a further pulse will usually appear on line 118<SP>1</SP> and this will reverse the trigger circuit 220, closing the gate 222 and opening a corresponding gate 221, and also setting another monostable flip-flop 223. Subsequently, the first mono-stable flip-flop 224 will return to its stable state but an output pulse from it will be blocked by the closed gate 222. Further pulses on line 118<SP>1</SP> will operate the trigger circuit 220 to and fro in a similar manner until the end of the pulse group is reached which results in the trigger circuit 220 remaining in one condition for more than 1¢ digit periods. Thus the mono-stable flip-flop (e.g. 224) which received the last pulse returns to its stable state while its associated gate 222 is still open and transmits a pulse which resets the trigger circuit 225. This closes the gate 117 and sends a pulse via an amplifier 120 to step on the counting-tube distributer which controls the gates leading to the counting-tube registers.