Patent GB-852182-A (GB)
Title: Cyclically operable electrical calculating apparatus
Inventor: GERHARD DIRKS
IPC: G06F7/52
Filed: 1955-10-21
Abstract: 852,182. Digital electric calculating-apparatus. DIRKS, G. Jan. 21, 1957 [Oct. 21, 1955 (2); Nov. 11, 1955], Nos. 30069/55, 30070/55 and 32249/55. Class 106 (I). Cyclically operable electrical apparatus for performing an arithmetical operation comprises means for effecting a division operation performed denomination by denomination on a numerical value, including means operable on each cycle to set a first pulse counter in accordance with the sum of a remainder obtained in any preceding cycle and a digit of said value, a second counter having a counting capacity equal to the factor by which each digit of said value is to be divided, a pulse generator adapted to apply groups of pulses to the second counter, the number of pulses in each group being equal to a factor by which each said digit is to be multiplied to give it denominational significance and the number of groups of pulses applied being controlled by the first counter whereby the remainder obtained in this cycle of operation is registered in the second counter, and means for forming the sum of each remainder and the next digit of the value to control setting of the first counter in the next cycle. The particular apparatus described is adapted to calculate the residue modulus 13 of the number 10#[)A + K)(mod. 13)], where A is the number initially registered in a modulus 13 accumulator and K is a keyboard entered decimal digit. This calculation is performed in the following stages: (1) A selected key is depressed and enters its complement on ten into a ten-cathode tube 5. A flip-flop 11 is then turned on to open gate amplifier 12 allowing clock pulses from a source 13 to pass to both tube 5 and a 13-cathode 3: this continues until tube 5 returns to zero when it resets flip-flop 11 to close gate 12. This results in the addition of the value of the depressed key to the modulus 13 accumulator, i.e. the number (A + K)(mod. 13) is now registered in tube 3. (2) When tube 5 returns to zero it also turns on a flip-flop 18 which opens gate amplifiers 19 and 20 allowing clock pulses to pass to a 13 cathode tube 1 and also to tube 3. This continues until tube 3 reaches zero when it resets flip-flop 18 and results in the transference to tube 1 of the complement on 13 of the number that was in tube 3, i.e. tube 1 now registers 13 - (A + K)(mod. 13). (3) When tube 3 returns to zero it also turns on a flip-flop 22 which opens a gate amplifier 24 allowing clock pulses to pass to a ten-cathode tube 2 and also to tube 3. Each time tube 2 passes through zero a pulse is entered, by it, into tube 1 until tube 1 reaches zero whereupon flip-flop 22 is reset. This results in pulses being entered into tube 3 so that this tube now registers At this stage the complete cycle can be performed again by depressing a further key. When the zero key is depressed step (1) above is bypassed and flip-flop 18 is set on immediately instead of flip-flop 11. During each cycle the actual quotient resulting when 10(A + K) is divided by 13 is registered in one of three dekatrons 32, 33, 34 (the apparatus having a capacity of four cycles). This occurs as follows : (a) During the first cycle, between steps 1 and 2, a distributer arm 35 is advanced to a contact 36. (b) The next " carry-pulse " (i.e. a pulse from the zero cathode) from tube 3 turns on a flip-flop 30 which opens a gate amplifier 31. (c) Subsequent carry-pulses produced by tube 3 pass via gate 31 to dekatron 32 until the end of the first step of the second cycle, whereupon flip-flop 30 is reset by the signal that sets flip-flop 18 and simultaneously distributer arm 35 advances to a contact 37. This recording cycle, which can be regarded as lagging a computing cycle in phase by one step, then repeats. The following table summarises the operation of the device when the digits 2, 4, 8 and 3 are keyed in this order. The contents of the various tubes are assumed to be zero initially and are quoted at the end of each step. In the table those carries from tube 3 in parentheses are those that open gate 31 and those carries which occur after cycle and step 4(2) are ineffective since the distributer arm 35 has then advanced to an open contact 36a. The result of these four cycles shows that a number 2,483 when divided by 13 has a quotient of 191 (the contents of tubes 32, 33 and 34) and a remainder of zero (the contents of tube 3). At the end of four cycles the contents of tubes 32, 33, 34 and 3 can be printed out this being effected by applying pulses to these tubes from a pulse generator 53 via diodes 561, 562, 563 and 58 in synchronism with the rotation of type wheels 42, 43, 44, 45 which are controlled to print by the differentially timed carries from the tubes 32, 33, 34, and 3. When the pulse generator 53 reaches its fourteenth contact it resets tubes 32, 33, 34 and 3 via diodes 621, 622, 623 and 60. It is stated that the remainder after dividing by 13 could be used as a check symbol. Details of the various flip-flops, gate amplifiers and counting tubes are given and in a modification the tubes 1 and 3 are replaced by a counting unit of variable capacity whereby a calculation of the form AÎB+C/D can be performed. Specification 852,183 is referred to.