Patent GB-707359-A (GB)
Title: Improvements in or relating to data storage devices
Inventor: KNIGHT LORIN
IPC: G11C11/404
Filed: 1952-11-21
Abstract: 707,359. Digital electric calculating apparatus ; statistical apparatus. BRITISH TABULATING MACHINE CO., Ltd. Nov. 21, 1952, No. 29466/52. Class 106 (1) An electronic data storage device comprises a thermionic valve V1, a condenser 7 in series with the anode-cathode circuit of the valve, data entry means R1 for charging the condensers and data read out means effective to cause conduction in the valve only if the condenser is charged. In the circuit shown in Fig. 1 one side of the condenser 7 is connected to the cathode of the valve V1 and the other side is connected to a negative supply line 2. The anode of the valve 5 is connected to a positive supply line 1 through a resistor 6, and the control grid 5 connected through a resistor 4 to a line 3 which is normally 90 volts negative with respect to the line 2. The condenser is normally uncharged so that the cathode is 90 volts positive with respect to the control grid and the valve is non-conducting. Any residual charge is dissipated momentarily closing a switch 9 which places a resistor 5 in shunt with the condenser. When an entry is to be made a relay R1 is energized, the cathode of the valve is then connected to line 8 through resistor 5 and contacts R1a. The line 8 is 70 volts negative with respect to line 2, so that the condenser charges and maintains the cathode at this potential when the relay R1 is de-energized and the contacts R1a open. The cathode is now 20 volts positive to the control grid, so that the valve is still non-conducting. To test whether the condenser has been charged the line 3 is momentarily reduced to -45 volts. If the cathode is held at -70 volts by the condenser the reduction in voltage of line 3 makes the control grid positive with respect to the cathode and the valve conducts. The valve current is drawn from condenser 7 and the valve continues to conduct until the cathode potential has fallen sufficiently for the cathode to grid voltage to reach cut-off. Conduction produces a voltage drop across the anode resistor 6, so that a negative pulse transmitted by a condenser 10 indicates that the condenser 7 was charged. By limiting the period of discharge of the condenser in relation to its size, it is possible to reduce the potential of line 3 several times for one entry into the storage condenser. A number of storage units are employed to provide a multidenominational temporary storage unit which is used for accepting data from record cards and is subsequently read out to an electronic calculator. The unit shown in Fig. 2 registers tens of shillings, shillings and pence. The cards are sensed in known manner by a contact roll 11 and brush 12, the timed impulse so derived is converted to a coded form according to the code 1, 2, 2, 4, for a decimal denomination and 1, 2, 2, 2, 4, for a duo-decimal denomination. This coding is preferred in order that the complement of the stored value may be read out if desired ; alternatively a 1, 2, 4, 8, code may be employed if this feature is not required. Fig. 2 shows valves V2-V6 inclusive for the pence denomination, V7-V10 inclusive for the shillings denomination, and V11 for the tens of shillings denomination. The anodes of all the valves in each denomination are connected through a single resistor to the positive line 1. The storage condenser 7 of each valve is connected through resistor 5 and a normally open contact of one of the relays R2, R3, R4, to the centre of the corespondingly valued transfer contact 15-19 inclusive. The centre of the transfer contacts are normally connected to the line 2 through a plug connection between sockets 20, 21. The control grids of the valves are normally biased to -90 volts by five lines 25 to 29 which are connected to the line 3 through similar resistors 30. The reduction in the potential of the read-out lines is effected by a commutator 24 which connects in turn each line so that the resistors 30, 31 form a potentiometer which reduces the potential of the line connected to a particular segment of the commutator to -45 volts. The commutator brush first contacts the single segment connected to line 25 so that any of the valves V2, V7 and V11 for which the condenser 7 was charged will conduct and produce a single negative impulse at the anode. The brush then contacts the two segments connected to line 26 so that this line is reduced to -45 volts twice in rapid succession, thus producing two negative pulses if the condenser of the valves V3, V8 has been charged. The remaining segments operate in similar manner. The negative pulses thus produced are fed via a condenser 32 to an electronic counter or other data receiving device. By reversing the connections shown at plug sockets 20, 21, 22, 23 so that the socket 23 is connected to 21 and 20 to 22 the condensers 7 are charged if the transfer contacts have not been operated so that if, for example, the value 7 is recorded the condenser 7 of valve V9 is charged, representing 2, i.e., the complement of the value 7. The mechanical commutator shown may be replaced by an electronic device producing positive pulses.