Patent GB-812015-A (GB)
Title: Improvements in or relating to information sorting systems
IPC: G06F7/24
Filed: 1956-05-09
Abstract: 812,015. Arranging digital data in sequence. LABORATORY FOR ELECTRONICS Inc. May 9, 1956 [Sept. 2, 1955], No. 14401/56. Class 106 (1). In an electrical data-sorting system, items of information stored on a main magnetic drum or in an equivalent store are sorted into a predetermined sequence by selecting, from sections of the store, the items to be chosen next in those sections and storing significant parts of those items on intermediate stores, and making the final selection of each item from certain parts only of the intermediate and main stores, the parts being chosen for each selection so as always to include the items to be selected. Information is stored in item blocks each containing an order (sequence) number and an address in binary-coded decimal form. The blocks are in random order, ten blocks to a track, on 1,000 main tracks of a magnetic drum, and are to be read out in sequence according to the order numbers, lowest first. For this purpose, 10 intermediate tracks, each accommodating 100 blocks, and one final track accommodating 10 blocks, are employed. Each block on the intermediate and final data-processing tracks contains only the order number and the address. Each address comprises four decimal digits of which the first three correspond to the main track and the last to the block in that track. The first digit corresponds also to the associated intermediate track and final block and the second and third digits to the associated block of the associated intermediate track. Initially, the block with the lowest order number is selected from each main track in turn, by means of a comparing device, which may, if the numbers are represented with the least significant digits leading, be as described in Specification 738,294. These blocks (order numbers and addresses only) are written in sequence on the intermediate tracks. The lowest order number blocks are then selected from the intermediate tracks in turn and written on the final track, from which the lowest of all may be obtained. Supposing this has address 4273, i.e. it was in blocks 21, 31 and 14, Fig. 4, of the final, intermediate and main tracks, then, to obtain the next item in the sequence, the remainders (shown black) of final track 13, intermediate track 17 and main track 15 only have to be searched. This is done during a first cycle, in which the previously located first item in the sequence is read from the appropriate main track, and marked to prevent re-selection. The blocks 31 and 21 are erased at the same time. In the second cycle, the second item is read out from its main track and marked; the order number and address of the item with the next lowest order number on the main track 15, on which the first item is stored, are written in the erased block 31 of the intermediate track 17; and the same information regarding the item with the lowest order number on the remainders of both main and intermediate tracks 15 and 17, is written in the erased block 21 of the final track. The selecting process continues in this manner, a new item being extracted during each cycle of the drum.