Patent GB-823782-A (GB)
Title: Improvements relating to apparatus for the automatic sorting of recorded data signals
IPC: G06F7/24
Filed: 1956-04-25
Abstract: 823,782. Sorting digital-data signals. DIRKS, G. July 19, 1957 [April 25, 1956], No. 12612/56. Class 106 (1). In apparatus for sorting groups of data characters by repeated selective transfer between a plurality of magnetic tapes, a first tape bearing the data to be sorted is fed in a forward direction and a selected character in each group of data characters is examined and controls forward feeding and recording of the data group on a selected one of a number of secondary tapes. On reaching the end of the data on the first tape the drive of the latter is reversed and the secondary tape drives are reversed in turn while the data recorded during the forward run is transferred back to the first tape. Representation of data.-As described, data items to be sorted are represented by signals on a five-channel magnetic tape, Fig. 1. A signal 10 in channel 5 marks the beginning and a signal 11 in channel 6 the end of one data item or word. Signals 9 in channel 4 separate decimal denominations while in channel 3 a group of ten signals occurs between each of the denomination marks 9. The digit values are represented by the positions of signals 7 in channel 2, these acting to terminate the counting of the signals 8 in each denomination. Thus the first three signals 7 represent digits " 4," " 3 " and " 7." Zero is represented by " 10." Sorting process.-In the embodiment, sorting is assumed to be based on three (the 30th, 31st and 32nd digits) out of eighty possible digits in each data item. During the first phase data items in random order on the first storage tape are distributed to ten secondary tapes according to the value of the 32nd digit, and then returned to the first tape in ascending order of this digit. A second phase is then carried out on the basis of the 31st digit, and at the end of the third phase, based on the 30th digit, the data items are arranged in the required order. Detailed operation.-Eleven tapes (Fig. 3, not shown) are individually driven through onerevolution, solenoid-controlled clutches between two sets of spools frictionally mounted on two parallel shafts which are urged in the appropriate direction according to the phase being carried out. One revolution of a feed roller, e.g. 34/11, Fig. 4, moves the tape through one data item (i.e. eighty digits). Selection of the digit (the 32nd) on which the first sorting phase is to be based is made initially by supplying forty-eight (the complement to 80) pulses on an input 41 to an eight-stage counter 40 (e.g. a multi-cathode tube or tubes). To start the sorting operation a solenoid 35/11 is energized releasing the feed roller 34/11 which drives the tape in the direction 43. The pulses 9, Fig. 1, picked up by a reading head 30/3 are fed via a gate 49 to step on the counter 40 which sends an output pulse to open a gate 52 when the 32nd pulse 9 is picked up. Pulses picked up from track 3 by a head 30/2 now step on a selector 54 which marks output lines 55/1 . . . 55/0 in succession until the digit-representing pulse 7, picked up by a head 30/1, opens all the gates 56/1 ... 56/0, momentarily, allowing an output pulse from the marked output line to pass through the corresponding gate. This signal closes the gate 52 and zeroizes the selector 54 via one of the diodes 59/1 ... 59/0, and also operates an associated trigger 63/1 . . . 63/0 which sends a pulse to fire the selected one of a series of gas tube relays 76/1 ... 76/0. The firing of this tube momentarily energizes a solenoid 35/1 . . . 35/10 in its anode circuit which releases a one-revolution clutch to feed the selected one of ten secondary tapes 28/1 ... 28/0 through one data item distance. During this movement reading heads 29/1 ... 29/5 read off the data item signals from channels 2, 3 and 4 of the first tape and the selected heads 75/1 ... 75/0 write them on to the selected tape. Subsequent items from the first tape 1 are distributed to the secondary tapes 28/1 ... 28/0 in a similar fashion; while the digits of one item are being transferred by heads 29 the next item is being sensed by heads 30. The data on tracks 2, 3 and 4 of tape 1 is erased by heads 94/1 ... 94/3 after being sensed. After all the data has been read from tape 1 a control device, operated, e.g. by sensing photo-electrically an end-of-data signal on tape 1, changes over switches 67, 69, 70, 72, 73, 85 and 93 from position a to position b, closes switches 95, 96 and 97, and opens switch 99. These changes provide for driving the tapes in the opposite direction and reversing the functions of read and write heads and their associated amplifiers. Starting with tape 28/1 the contents of each secondary tape are transferred in succession to tape 1, or, possibly, to a further tape, and the tapes wiped clean by erase heads 106/1 ... 106/0. The end of each secondary tape is sensed by a head 103/1 ... 103/0, the signal from the last one setting the counter 40 to examine the next digit and initiating a second sorting phase from tape 1 to the secondary tapes. Instead of tapes, discs, drums or other erasible stores may be used and alternative ways of representing digits and alphabetical characters are suggested.