Patent GB-789486-A (GB)
Title: Digital computer electrical data classifying system
IPC: G06F7/24
Filed: 1956-01-09
Abstract: 789,486. Classifying digital data. NATIONAL CASH REGISTER CO. Jan. 9, 1956 [Jan. 27, 1955], No. 657/56. Class 106 (1). In an electrical system for classifying selected data items contained in data entries (serial arrays of binary coded information) stored in a cyclical memory of a digital computer, including a recirculating register synchronized to advance with the memory, coded signals representing one of the selected items is set up in the register to serve as a datum, and a counting device is controlled in accordance with the relative magnitude of the datum with respect to the selected data items and controls logical circuitry for producing output signals representing such relative magnitude, which output signals are transferred to a storage location of the memory. The system described forms part of a computer similar to that described in Specification 770,952 comprising a magnetic storage drum 101, Fig. 1, having a clock pulse channel 108 controlling binary and octal digit-period-defining counters 117, 118, an arc address channel 109 (see Fig. 13a) containing 64 successive octal numbers 0-77 each defining the address of the word next to be read from a main memory channel such as 111, a synchronizing channel 109a, and channels forming with the arithmetic unit 114 one-word recirculation register E, F, G, H. The unit 114 comprises bi-stable hard valve trigger circuits (called " flip-flops ") and a logical diode gating network. The operating sequence is determined by programme counter 115 controlled by flip-flop Kl so as either to step on to the next value, or to skip or stay in the same condition, at the end of each word period. Fig. 9 shows the programme counter sequence for carrying out a classify command (the steps being indicated by octal numbers), only the portions of the computer directly concerned with this operation being described in detail. The operation essentially comprises determining the relative magnitude of selected data items comprising control numbers each forming part of a word or group of words on channel 111, and recording corresponding numerical tags on a further drum channel 110, Figs. 1 and 13a. The entries on channel 111 may be obtained from record tapes and may each comprise 1, 2, 4 or 8 words, the entry length being coded in position O, of register G, and the control digits are determined by recording 1's in corresponding digit positions in register F. During the first classify command step PC455, the first control word (i.e. that word in the first entry which contains the control digits), whose address is given by the command word, is entered via selection gate 167 into register E to be used as a standard. The programme counter then steps to PC456 which is repeated while the control number in E is compared successively with the control number in all the other entries, and whenever the number in E is greater, a value equal to the number of words in an entry is entered into a counter comprising flip-flops A1-A6. The control words are detected by comparing the entry length indication in G with the registration in H which is arranged to act as a counter stepped on one for each word period. After the end of the last word of the last entry to be compared, the programme counter steps to PC457 in which the amount registered on the counter A1-A6, plus a further entry length number if a successful comparison has taken place during the preceding word period, is passed via gate 116 to channel 110 where it is recorded opposite the first word of the control entry on channel 111. Step PC457 is repeated for a further word period for each further word in the entry, and amounts successively increased by one are recorded on 110 (see e.g. entries 10, 11, 12, 13, Fig. 13a). During the subsequent steps PC460 to PC467, the words of the second entry are set up in turn in register E and " 1 " is added in the H- counter. When the amount in H indicates that the control word of this entry has been set up, the programme sequence PC456, PC457 is repeated, and so on until all the entries have been dealt with. During the second and subsequent PC456 steps, when the control number in E is compared with numbers which have already been used as a standard (i.e. numbers which are read from 111 after, the " 0 " or datum position has been passed on synchronizing channel 109a) an entry is made in counter A1-A6 also when the compared values are equal. The " 0 " indication in channel 109a is used also during PC460 to PC467 to indicate that operations are completed, the programme counter then stepping through to the rest condition (PCO). In the example illustrated in Fig. 13a, the 4-word entries relate to sales transactions in retail chain stores, and are compared in accordance with a stock number recorded in the second word W1, W2-W16. The octal values shown in channel 110 indicate that for the first, second, third and last entries, the stock number was the third smallest, largest, smallest and second largest respectively.