Patent GB-837197-A (GB)
Title: Improvements in electric calculators
IPC: G06F7/50
Filed: 1956-03-27
Abstract: 837,197. Digital electric calculating apparatus. DIRKS, G. March 27, 1956 [March 30, 1955], No. 9441/56. Class 106 (1). Calculating-apparatus operating on successive denominations of a number in successive cycles, includes a magnetic signal store comprising a track divided into a plurality of digit storage areas each adapted to store denominational digit signals, a sensing head for reading off the signals in the first half of each successive digit cycle, a digit-summing device controlled by the stored signals and other number representations and generating corresponding result signals, and means controlled by the result signals to energize a recording head whereby a result digit is recorded during the second half of each cycle in the storage area from which the corresponding digit was sensed during the first half of that cycle. As described, one factor is entered on a keyboard which causes horizontal rows 9<SP>0</SP>, 91 ... &c. representing the denominations of the number, to be connected to selected columns 8<SP>0</SP> ... 89, representing digit values ("28 " is set up in the drawing as shown). The digits of the other factor are derived successively from a magnetic drum 1 on which they are represented by the position of a gap in each digit period of a sine wave recording. The sine wave signal is picked up by a head 4 and passed via an amplifier 26 to a two-state device 6 which, upon detecting a gap in the sine wave, delivers an output pulse via a distributer 11 which rotates in synchronism with the magnetic drum 1. Coupling between the distributer arm and the output leads to the keyboard may be capacitative, inductive, or by direct contact, and the pulse delivered while the arm is associated with a particular denomination of the keyboard passes via the contact established by a depressed key in that denomination if any, to a contact ring 13<SP>0</SP> ... 13<SP>9</SP> representing the key value on a second distributer 14. Again, various types of coupling are suggested for transmitting the pulse to one of the output lines 14<SP>0</SP> ... 14<SP>18</SP> of this distributer; the line selected in this case represents the sum of the digit set up on the keyboard and the digit represented by the timing of the pulse initiated by the interruption in the waveform recorded on the drum 1. The signal picked up by the lead representing the sum digit causes the corresponding triode of a series 15<SP>0</SP> ... 15<SP>9</SP> to become conductive; also where the sum exceeds the value 9, a " carry " signal is registered in a device 19. The result of the computation is recorded on the drum 1 by a head 5 under control of a circuit shown in Fig. 2. The sine wave recording signal is picked up from a permanent track on the drum by a head 28 and, after amplification, is applied to the grid of a triode 29, the output from its anode being fed via a transformer 39 to the recording head 5. The operation of the triode 29 and another triode 31, is controlled by a flip-flop 32, 33 which is in the LH-side-conducting state while the triode 29 is operative. A positive signal received at an input terminal (44) flips the device to RH-side conducting and the voltage drop at the RH anode biases the grid of the triode 29 beyond cut-off. On the other hand, this action removes cut-off bias from the triode 31 whereby high-frequency signals from a generator 25 are passed through the valve and the transformer 39 to the head 5 causing erasure of any signals passing under the head at this time. The timing of this brief erasing signal is dependent on the time of coincidence of an output distributer arm 21<SP>1</SP> with that one of the leads 22<SP>0</SP> ... 22<SP>9</SP> which is connected to the conducting triode of the series 15<SP>0</SP> ... 15<SP>9</SP>. Carry from a lower denomination is accounted for by bringing into use, instead, a secondary arm 21<SP>2</SP> spaced the appropriate angular distance from the arm 21<SP>1</SP>. Specifications 786,021, 786,033 and 837,196 are referred to.