Patent GB-888866-A (GB)
Title: Improvements in or relating to data processing equipment
IPC: G06F7/24
Filed: 1958-02-21
Abstract: 888,866. Sorting digital data. GENERAL PRECISION Inc. Feb. 21, 1958 [Feb. 21, 1957 (2)], No. 5802/58. Class 106 (1). Means for sorting words called " records," each record having a control field, comprises first and second input channels for receiving simultaneously two words, precedence-determining circuitry to compare the two control fields, first and second output channels, and record-routing circuitry operating under the control of the precedence-determining circuitry for directing the record of higher order to the first output channel and the record of lower order to the second output channel. As shown in Fig. 1, a " two line sorting switch " for sorting records in binary code comprises input channels A, B, a decision circuit X, and a gating circuit Y for routing the input records from A, B appropriately to " high " and " low " output channels H, L. Normally, triggers 17, 18 are reset to keep open " and " gates 19, 22, thereby maintaining channel A connected to channel H and channel B to channel L. This connection is retained while identical bits occur at A and B and the switch is latched by the occurrence of a " 1 " or " high " value at A with a " 0 " or low value at B. When this occurs, an " and " gate 13 passes a low output to an inverter 14 which feeds " and " gates 15, 16 with a high value. The gate 15 is thus fed with high values and is opened to set the trigger 17 thereby maintaining the gate 16 closed by the " 0 " output of the trigger 17 until the occurrence of a reset pulse at the conclusion of the passage of the pair of records being compared. However, should the first difference between the records be a " 1 " at B occurring simultaneously with a " 0 " at A, the gate 16 is opened to set the trigger 18, thereby opening " and " gates 20, 21 and closing the gates 19, 22, to route the input at A to L and the input at B to H until the next reset pulse at the conclusion of the records resets the trigger. The sorting switch, Fig. 1, may be employed at 114, Fig. 3, in a circuit adapted to sort a serial file of records, the file being passed from an input C to a track 31a of a magnetic drum 31, and sequentially from track to track of the drum by read heads such as 34a and write heads such as 33b, so that the tracks 31a, 31b &c. form in effect one continuous " helical " path, a track 31e serving as a sorting track. Sorting is effected by reading successive records from the track 31e by heads 37, 38 and re-recording the record by heads 32, 39 in the order determined by the sorting switch 114, a permanent erase head 35e being provided between the heads 38, 39. The re-arranged data is read from the track 31e by a head 115 and returned to the track 31a via a switch S1 which is closed while sorting takes place. A cycle in which the complete file of records passes through the switch 114 is called a pass, and after repeated passes the file will be arranged in the required order. A clock track 30a on the drum supplies timing pulses to the switch 114 and pulses being counted by a counter 116 which provides an output corresponding to the passage of a complete record to reset the switch 114, the outputs being counted by a record counter 117 which provides an output to a drum revolution counter 118 adapted to feed a pass counter 47 which counts the number of passes made by the complete file. To detect asynchronous running, the counter outputs are fed to an " and " gate 42 which provides a normally high output to an inverter 45, so that an " and " gate 43 which is supplied from the inverter 45 and also from the clock track 30a is normally closed, but is opened should asynchronism result in closure of the gate 42 to provide an indication at 46. A sequence-checking switch 120, similar to Fig. 1, but reset only after the completion of a pass, is adapted to compare consecutive records in the file by reading heads 48, 49, the trigger 18, Fig. 1, being normally reset, to provide an output indication (not shown), but set when two records in the file are not in the required order. When the sort is completed, the sorted file may be obtained as an output at D. A modification is described (Fig. 6-8, not shown) in which sorting is effected on records in which a character is represented by five binary bits in parallel (e.g. on parallel tracks of a magnetic drum). Sorting switches capable of dealing with three or more records at a time are described, Figs. 9, 10, only Fig. 9c, which shows a five-line sorting switch, being shown, these switches being formed by connecting together a pluralityof two line switches of the kind shown in Fig. 1. The application of a three-line sorting switch to the sorting of a complete file is described, with reference to Fig. 11 (not shown), which corresponds to Fig. 3.