Patent GB-705574-A (GB)
Title: Improvements in electronic multiplying apparatus
IPC: G06F7/62
Filed: 1950-06-14
Abstract: 705,574. Digital electric calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd. June 14, 1950 [June 18, 1949], No. 14860/50. Class 106 (1) Apparatus for multiplying two multi-denominational numbers without column shift comprises multiplier and multiplicand registers and an electronic accumulator into which the multiplicand is repeatedly added under control of an electronic counter associated with the multiplier register. Pulse generators.-The anodes of a doubletriode 90, Fig. 36, connected as a multivibrator are capacity-coupled to the grids of amplifying triodes 96 E, 96 F respectively. The anodes of these triodes are connected to leads 10 E, 10 F on each of which appear alternate positive and negative pulses. The E pulses are 180 degrees out of phase with the F pulses. The lead 10 F is connected to the input terminal of a group of four hard-valve trigger pairs T1, T2, T4 and T8 connected in series and normally haying their left-hand sections conducting. These trigger pairs are responsive only to negative pulses, the eighth of which causes the trigger pair T8 to switch to produce positive and negative pulses on leads 11D and 11C capacity-coupled to the left- and right-hand anodes respectively. The sixteenth negative pulse switches the trigger pair T8 back to its normal state and consequently produces negative and positive pulses respectively on the leads 11D, 11C. The C and D pulses are thus 180 degrees out of phase and are produced at one-sixteenth of the rate at which the E and F pulses are produced. Multiplier unit.-The multiplier is manually set on three banks of keys associated with switches USD-9 TSO-9 and HSO-9, Fig. 3c, for the units, tens and thousands respectively. Each order comprises ten hard-valve trigger pairs, e.g. MpTU 0-9 for the units order. Throughout an operation, positive D pulses, inverted by a gate circuit (see below), are applied simultaneously through a lead 58 and condensers 104, 104a to the left-hand grid of the trigger MpUT9 and the right-hand grids of the triggers MpUT8-0. Each of these triggers is normally conducting in its left-hand section. The first pulse switches the trigger MpUT9 and the consequent drop in the potential of the right-hand anode, which is capacity-coupled to the left-hand grid of the trigger MpUT8, switches the latter trigger. The left-hand anode of the trigger MpUT8 is capacity coupled to the left-hand grid of the trigger MpUT7 so that when the second pulse is applied to the lead 58, the trigger MpUT8 is restored and the trigger MpUT7 is switched. Subsequent pulses switch the triggers MpUT6 to MpUT0 in turn. The tenth pulse restores the trigger MpUTO so that a negative pulse is applied through leads 64, 65, connected to the left-hand anode of the trigger MpUT0, to the right-hand grid of the switched trigger MpTU9, to restore it. The lead 64 also provides the input pulses to the tens order which comprises triggers MpTT9-0 connected in the same fashion as the triggers MpUT9-0. The one-hundredth pulse restores the trigger MpTTO, the left-hand anode of which is connected to a lead 66 to provide the input pulses to the hundreds order of triggers MpHT9-0. The trigger MpHT9 normally conducts in its right-hand section but is switched at the beginning of an operation (see below). The left-hand anode of the trigger MpHTO is connected by a lead 54 to the control circuits to stop the operation when this trigger is restored after one thousand pulses. One terminal of each of the units switches is connected to a lead 68, the other terminals being connected to the right-hand anode of the trigger MpUT9 and to the left-hand anodes of the triggers MpUT8-0 respectively. Similarly the tens and hundreds switches are connected to their associated triggers and to leads 69 and 70 respectively. The latter leads are connected to the control and suppressor grids of a pentode 60a, Fig. 3a, so that when the triggers associated with the closed tens and hundreds switches are both conducting in their right-hand sections (or in the left-hand sections in the case of the triggers MpTT9 and MpHT9), the pentode 60a conducts. Its anode is coupled to the grid of a triode B61 which is thus rendered non-conducting to raise the potential of its anode and the suppressor grid nf a pentode 62a coupled thereto. The units lead 68 is connected to the control grid of this pentode so that when the trigger associated with the closed units switch is next caused to conduct in its right-hand section (or, in the case of the trigger MpUT9, its left-hand section), the pentode 62a conducts. Its anode is coupled to the grid of a triode B63 which is thus rendered non- conducting to produce a negative control pulse on a lead 71 capacity-coupled to its anode. This control pulse causes each of the remaining C pulses (equal in number to the multiplier set on the keys) to effect an entry of the multiplicand into the result register (see below). Multiplicand unit. - The multiplicand is manually set on switches MS0-9, Fig. 3b, there being a units, a tens and a hundreds switch for each digit. Hard-valve trigger pairs MT1-9 are associated with the switches MS1-9. When entries of the multiplicand are to commence (see below) a positive bias is applied to a lead 41 connected to the right-hand grid of the trigger MT9. This trigger is thus switched by the next of a series of positive pulses applied simultaneously to the right-hand grid of each of the triggers through a lead 38. These pulses are derived from the E pulses (see below). The left-hand anode of each of the triggers is coupled to the right-hand grid of the next lower trigger and consequently, when the trigger MT9 is switched, it conditions the trigger MT8 which is itself switched by the succeeding pulse. The lower triggers are switched in turn and when the trigger MT1 is switched the rise in potential of a lead 44 connected to its left-hand anode effects a control which results in a negative pulse being applied to the input lead 38 to restore all of the triggers simultaneously (see below). One terminal of each of the units switches MS0-9 is connected by a lead 32 to the control grid of a gate pentode G23, Fig. 3a. Similarly, the tens and hundreds switches are connected by leads 33, 34 to gate pentodes G24, G25. The other terminals of each group of switches MS1-9 are connected together to the right-hand grid of the associated trigger. Consequently, during each cycle of the multiplicand device, while the trigger associated with a depressed switch is itself switched, the corresponding gate triode is conditioned to pass E pulses applied through the lead 10E to its suppressor grid on to the corresponding order of the results register (see below). The other terminals of the group of switches MS0 are connected to a negative source of potential so that when one of these switches is closed, the associated gate pentode cannot conduct. Thus, the multiplicand is entered once into the result register during each cycle of its operation. Result register. Transfer arrangements.-The results register comprises units, tens and hundreds orders RRV, RRT and RRH, Fig. 3d, and three overflow orders (not shown). To effect entries, the anodes of the gate triodes G23, G24 and G25, Fig. 3a, associated with the multiplicand unit, are connected by leads 29, 16, 19 to the input terminals of the three lowest orders of the result register so as to apply negative pulses thereto. Each order comprises four hardvalve trigger pairs UT1, UT2, UT4 and UT8, representing the digits 1, 2, 4 and 8 respectively and interconnected to count in binary fashion up to a count of nine. The tenth pulse restores the switched trigger UT1 to cause a drop in the potential of its left-hand anode which is connected by leads 140, 145 and a condenser 144 to the right-hand grid of the trigger UT8 to restore the latter. The consequent increase in the potential of the right-hand anode of the trigger UT8 is applied by a lead 141 and condenser 142 to the left-hand grid of the trigger UT2 to prevent the switching of this trigger. At the same time the decrease in the potential of the left-hand anode of the trigger UT8, which is capacity-coupled to the left-hand grid of a transfer storage trigger TCU, switches the trigger TCU. This switching is effected by a pulse derived from a positive E pulse. The next negative E pulse is applied by the lead 10E and a lead 12 to the right-hand grid of the trigger TCU and restores this trigger. The consequent increase in the potential of its right-hand anode produces a positive pulse at the grid of a pentode B14, Fig. 3a, connected thereto by a lead 15 to render it conductive. The anode of the pentode B14 is connected to the input lead 16 of the tens order and consequently a negative transfer pulse is entered into that order which cannot coincide with a direct entry pulse from the gate G24. A similar transfer arrangement is provided between the tens and hundreds orders, the transferstorage trigger TCT being associated with a pentode B17. The triggers T8 of the hundreds and higher orders are directly coupled to the triggers T1 of the next higher orders. A neon lamp, e.g. 151, is associated with each trigger to indicate whether or not it is in its registering state. Operation. Control circuits. - Momentary depression of a switch 50, Fig. 3b, applies a positive pulse to the grid of a triode C160, the negative pulse at the anode of which is applied through leads 52, 53 to the left-hand grid of a hard-valve trigger pair 49, Fig. 3a, and to the right-hand grid of the trigger MpHT9 of the multiplier unit. These triggers are thus switched from their normal states to conduct in their right- and left-hand sections respectively. The consequent rise in potential of the right-hand grid of the trigger 49 is applied by a lead 55a to the control grid of a pentode G51 to condition it so that subsequent positive D pulses applied to its suppressor grid throug