Patent GB-780596-A (GB)
Title: Improvements in or relating to record card controlled calculating apparatus
Inventor: WOODS-HILL WILLIAM
IPC: G06F3/08
Filed: 1954-10-18
Abstract: 780,596. Digital electric calculating-apparatus; statistical apparatus. BRITISH TABULATING MACHINE CO., Ltd. Oct. 18, 1955 [Oct. 18, 1954], No. 29972/54. Class 106 (1). In a record card controlled electronic calculating machine of the kind having record sensing means for producing electrical signals representative of the sensed data, recording means for recording on the same cards the result of calculations made in a calculating unit on the sensed data and feed means for passing the cards in succession through the sensing means and the recording means, the card takes at least two card cycles to pass through the sensing station to the recording station and a data store arranged to hold, prior to calculation the data sensed from a card until calculation on the data of a preceding card is completed. As shown in Fig. 6, the cards are fed from a hopper 201 through the sensing station 203 between feed rollers 204, 215, under the recording punch 205, through another sensing station 208 and to a hopper 209. The sensing station 203 and the recording punch are separated by two card lengths, so that the first card is being punched while the third is being sensed. The second card occupies an intermediate blank or buffer position. The card sensing provides a single impulse for each denomination of a number, the differential timing of the pulse indicating the digital value. Digits are stored and operated upon in the calculating unit in coded form using a combination of the values 1, 2, 4, 8 and each timed impulse is converted to this code before transfer to the input store. The four possible code values in each denomination are operated upon simultaneously but the denominations are operated upon in sequence beginning with the lowest order. The input and output of data and the transfer of data between stores and the calculating unit is described with reference to Fig. 1. Three types of storage means are used, a magnetic drum 1, four shifting register stores 2, 3, 4 and 5 and a capacitor storage unit 39. The drum 1 has three sections : a timing track 6 providing a series of clock impulses, an input and output buffer store 10 and a main computing store 9. Digits entered in the input section of buffer store 10 from the sensing apparatus and digits entered in the output section from the main store 9 are recorded on the same track, but the timing of the recording is such that they occupy different drum positions. The input and output sections therefore form two independent buffer stores sharing the same recording and reading equipment. Each of stores 9 and 10 consist of four tracks to receive the four code components of a number. There are four recording and reading heads for each of these stores. Each track also has an erasing head. The recording heads of store 9 are fed from four amplifiers 11. A dot inside a component symbol indicates that there are actually four units, one for each track but only one is shown. Data is recorded in store 10 by recording heads fed from amplifiers 12 and data is read out of both stores 9 and 10 through amplifiers 13, 14 which are connected to set up triggers 15, 16. Data stored in stores 9 and 10 is continuously circulated., being recorded on one side, read out in the same revolution of the drum by read heads, and fed back to the recording heads. The stores 2, 3, 4, 5 each consist of four shifting registers. Stores 2, 3, 4 consist of ten stages and store 5 of twenty-two stages. The last stage of each store is read out by gates 21, 22, 23 and 120 operated by the shifting pulses applied to the store. The output from gates 21, 22, 23 can be fed through gates 25, 26, 27 to line 24 or through gates 29, 30, 31 to line 28. The stores can all be connected in series to form a " long " register by opening gates 32, 33, 34. The output from gates 120 can be fed to line 24 through gates 35 or it can be recorded in store 10 through gates 37. Up to 52 digits can be read from a card, there being 52 brushes 38. The values read by the brushes are held in capacitor storage unit 39 before transfer to the input section of store 10. The units of store 39 are connected to a commutator 40 which converts the digit pulses read out from the store into coded form on a scale of 1, 2, 4, 8. In this form the data is recorded in sequence on the four tracks of store 10. At the time the third card is being sensed, the results of the calculations upon the data sensed from the first card is being punched in the first card at the punching station. Thirteen timing pulses from section 6 constitute a minor cycle and twenty-one minor cycles constitute a major cycle and correspond to one revolution of the drum. A timing unit is provided for this purpose, the first being a shifting register having thirteen trigger stages connected in a closed loop, and the other being a shifting register having twenty-one stages connected in a closed loop. The first unit is controlled by negative pulses, applied to all triggers simultaneously, the pulses being supplied by an amplifier fed through an inverter from the reading head of the clock pulse track 6 on the drum. The triggers forming the major cycle timing unit are governed by pulses derived from a point on the minor cycle loop. The 52 digits in the input section of store 10 are transferred to the long register in four minor cycles by opening gates 41, 42 and closing gate 41a to stop circulation. The digits are retained in the long register until the end of the major cycle. During the following major cycle the contents of the long register are read out to line 24 through gates 35, and entered in store 9 through adding unit 43. The distribution of data when transferred from the long register to the store 9 is controlled by a series of pluggable sockets. This unit is inoperative during transfer but at the end of the transfer calculations begin and the results are fed into store 9. From store 9 the results to be punched are transferred to the output section of store 10. The data from this buffer store is punched out by making plug connections from a group of sockets 52 to the punch magnets for the columns of the card in which the values are to be punched. Each punch magnet is energized through a tetrode 54 controlled by a coincidence circuit 53. The inputs to circuits 53 come one from triggers 16 and the other from lines connected to the commutator 40. The four rules of arithmetic are performed as follows:-Numbers to be operated upon are transferred from the store 9 via the gates 48 and the adding unit 43 to one or more of the stores 2, 3, 4. Entry into these stores from the adding unit 43 is controlled by the gates 138, 139, 140. By operating gates 141, 142 or 143 connecting the outputs to the inputs of the store a number can be continuously circulated in the store. Addition is performed by the adding unit 43, the two inputs to which come from lines 24, 28. Numbers to be added are gated out from the stores to these lines and the resulting sum output is entered into one of the stores to be used for further calculations or to be transferred to the store 9. Subtraction is effected by adding the complement value of one number to the true value of the other. Means are provided in adding unit 43 for complementing a number transferred from the line 24. Multiplication is effected by the " halving and doubling " process (see Specification 767,692). Division is effected by repeated subtraction of the divisor from one digit of the dividend at a time (as described in Specification 780,431). The calculator is also adapted to operate on a non-decimal and non-uniform notation such as sterling. The adding unit 43 operates basically on a scale of 16, but corrections are made to convert to a decimal scale by the insertion of " filler digits." For operation in scales of 12 for pence and 20 for shillings different filler digits are inserted. A series of gates, each connected to the input of a stage of the major cycle timing unit, are provided with control sockets pluggable to the sockets of a programme timer. By this means a number of operations can be selected to be performed in succession. Specification 673,759 is referred to.