Patent GB-817596-A (GB)
Title: Improvements relating to the transferring of magnetically recorded data items
IPC: G06F7/24
Filed: 1956-08-24
Abstract: 817,596. Sorting digital data. DIRKS, G. Aug. 14, 1957- [Aug. 24, 1956], No. 25889/56. Class 106 (1). Data-sorting apparatus by which data items are transferred selectively in successive runs in dependence on sorting signals, includes additional sensing means which, during a sorting run, tests for the presence of the next and, preferably, other sorting signals in the sequence so that, if some do not occur, subsequent sorting runs based on the missing signals may be skipped. Data representation.-Data items to be sorted are stored in random fashion on a multichannel tape 1, each item corresponding with an eightycolumn record card. Signals in a track 5 mark the beginning, and signals in track 6 mark the end of each item. The decimal digits are separated by signals in a track 4, groups of ten pulses each occurring, in track 3 between each pair of digit-separating signals. The actual digit values are represented by differentially positioned signals in track 2, the number of track 3 pulses occurring between each of these signals and the associated track 4 signal representing the digit value in each case. Alternatively, coded-decimal representations could be used ; also, alphabetical characters could be provided for. Sorting procedure.-During each run-through of tape 1, sorting by selection is based on one digit value in one column position of each data item. Thus, for example, during the first run-through only those items found to have " O " in the thirty-second column will be transferred to a secondary tape 17. Tape 1 will then be rewound and, during a second run-through, items having " 1 " in the control column will be transferred, and so on for the remaining digit values. Tapes 1 and 17 will then be rewound while the partially sorted data is transferred from tape 17 back to tape 1. Further series of runs based on another control column of each item will ensue until the data has been brought into the required order. In another embodiment the selected items are recorded on tape 17, as before, and non-selected items are recorded on a further tape (Fig. 2, not shown), the contents of which are transferred back to tape 1 after each run-through. During transfer operations erasing heads wipe redundant data from the sorting tapes. Skipping redundant operations.-During the first sorting run the digit in the control column is examined not only to determine whether it is " O," but also to compile a record of the digit values occurring in this position. This record is used when the digit value is changed for a new run through and makes it possible to skip over digit values which do not occur. In a simpler form only the next following digit may be checked for occurrence during each run. Operation.-As described, sorting takes place on the basis of the number in columns 30, 31 and 32 of each data item. An eighty-stage counter 21 is set to register the complement of the lowest-value digit column (48= complement of 32) by pulses fed in on a lead 22, a contact 24 is closed to supply positive potential from terminal 25 to open a gate 26, and a solenoid 10 is energized to release the roller 8 which drives the tape 1 bearing the data items to be sorted past sensing heads 14A. . . 14D. A signal from track 5 marking the beginning of a data item is passed through the gate 26 to open a gate 27 so that signals from track 4 marking the beginning of each digit or column can now pass to the counter 21, stepping it on until, after thirty-two pulses, an output signal from the counter opens a gate 28 to allow the group of ten pulses from track 3 to step a multicathode counter tube 23 through a complete cycle. During this time the differentially positioned signal from track 2 representing the digit value is applied to gates 39 and 41 ; gate 39, opened by the signal from counter 21, allows a pulse through to open a further gate 37. Output lines from the cathodes of tube 23 are connected via diodes with corresponding output lines from a similar tube 29 to form AND gates whereby, if the two tubes register the same digit when the track 2 signal is applied to the gate 41, the latter is opened to allow the signal to pass through and set a trigger 43 which primes a gas relay 45 for subsequent firing by a track 5 signal picked up by one of a second group of read/record heads 15A. .. 15E. The firing of tube 45 energizes a solenoid 19 to release the feed roller 18 of the second tape 17, and the firing signal also opens a gate 53 to allow a setting of a second trigger 52 which conditions amplifiers 50 to receive data signals from the tracks 2, 3, 4 for recording by heads 44. When, during the first run with the selector tube 29 set at " O " the digit represented by the pulse from track 2 is not " O," the gate 41 blocks its passage and prevents any operation of the secondary tape. However, control digits other than " O " are registered on a nine-stage shifting register 40/1 . . . 40/9. Each output line 31/1...31/9 from the selector tube 23 is connected to a corresponding gate 38/9 (only one of the nine is shown) so that when the digitrepresenting pulse from track 2 occurs, it passes via gates 39, 37 and the gate conditioned by the output line 31/1 ... 31/9 at that moment, and sets the corresponding stage of the shifting register 40/1 ... 40/9. End of a run.-An end-of-tape signal picked up by a head 16 sets a trigger circuit 56 which causes, after a suitable delay, reversal of the tape 1 drive by energization of a relay 60, and also opens a gate 64 to allow a pulse generator 68 to feed the shifting register 40/1 .. : 40/9 and also step on the selector tube 29. If a signal has been stored in stage 40/1 it will, in shifting out of the register, immediately close the gate 64 against further pulses from generator 68 ; if no significant signal has been stored the register 40/1...40/9 and selector tube 29 will be stepped on, thus obviating unnecessary runs. The signal from the shifting register 40/1 ... 40/9 also operates through an inverter 59 to cause a solenoid 67 controlling the resumption of the forward drive of tape 1, to be energized. Another solenoid 71 is energized after control by digit " 9 " to cause both tapes to be rewound &c., as described above ; a fourth solenoid 86 initiates the next phase based on column " 31 ".