US2591007A - Electronic accounting machine - Google Patents

Description

April 1, 1952 c. F. RENCH 2,591,007

I ELECTRONIC ACCOUNTING MACHINE Filed Dec'. 17, 1949 v4 sheets-sheet 1 HIS ATTORNEYS Filed Dec. 1'7, 1949 c. F. RENCH 2,591,007

ELECTRONIC ACCOUNTING MACHINE 4 Sheets-Sheet 2 INVENTOR CARL F. RENCH BY awe/'M Mw] 7%@ HIS ATTORNEYS April 1, 1952 c. F. RENCH 2,591,007

ELECTRONIC ACCOUNTING MACHINE Filed Dec. 17, 1949 4 Sheets-Sheet 3 BY a/v@ HIS ATTORNEYS April 1, 1952 c. F. RENcl-l ELECTRONIC ACCOUNTING MACHINE 4 Sheets-Sheet 4 Filed Deo. v17, 1949 ID p..

' CARL F. RENGH BYMZ/ M /w ZM@ HIS ATTORNEYS Patented pr. 1, 11952 ELECTRONIC ACCOUNTING BIAGI-HNE Carl F. Bench, Troy, Ohio,l assigner to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland Aapplication December 17, 1949, Serial No. 133,540 5 claims. (Cl. 2504-27) This invention r tes to electronic accounting machines and in particular to an improved controlled digital electronic impulse generator and ccumulator with readout and digit-manifesting means therefor.

The novel impulse generator is of a type which is capable of effecting entries simultaneously in a plurality of denominational orders oi an accumulator. The impulse generator utilizes a plurality of tubes, Which are common to a plurality of denominational orders, for producing impulse trains corresponding to the digits 1" to 9 and containing corresponding numbers of impulses. These impulse trains, which are available to the pluralit7 of denominational orders, may be selectively switched to any one r more denominational output conductors of the impulse generator by corresponding denominational digitselecting means.

The plurality of tubes of the impulse generator includes an oscillator-controlled means for producing driving impulses, a chain of tubes containing a start tube and a priming tube for each of the digits l to 9, and an impulsetrain-producing tube for each of the priming tubes. The priming tubes are driven by the driving impulses, once the start tube has been rendered conducting, and will become conducting one after another in sequence, beginning with the 9 tube and ending with the l tube. As each priming tube becomes conducting, it conditions a related impulse-train-producing tube also to respond to the driving impulses and produce an impulse train containing the number of impulses corresponding to the value of the priming tube. As soon as the impulse trains have been produced, the start tube and the priming tubes are returned to their non-conducting status and made ready for another amount-entering operation.

The impulse-train-tube circuit provides a low impedance source for the impulses which is capable of producing extremely strong impulses, so that their quality will not be impaired and they will be able to produce satisfactory operation of the accumulator even though the impulses are switched simultaneously to a plurality of denominational output conductors to cause entries to be made in corresponding orders of the accumulator. This circuit also minimizes cross-- talk or interference effects between conductors forming the output circuits. l

The oscillator of the impulse generator is also used to control a further impulse-generating means to provide tens-transfer-effecting impulses for causing tens transfer entries to be made in the accumulator, when required, and in such a manner as not to interfere With the normal digital entries in the accumulator.

1 The novel accumulator is made up of a plurality of denominational orders, each order of which contains an electronic coupling device through which digit entries and tens transfers are made, a pair of tubes connected as a trigger pair and operable to effect tens transfers, and four pairs of tubes connected to operate as trigger pairs, each trigger pair being operable to an on condition and an oil condition, and further connected for accumulating digit values in the decimal notation and representing the units digit or the accumulated sum in that order, by predetermined combinations of on and off conditions of the trigger pair. between the four trigger pairs, by which they are enabled to count in the decimal notation, connect the trigger pairs in cascade and also provide certain feed-back circuits, whereby the last trigger pair of the cascade, upon its being turned on can cause an automatic operation of one of the previous trigger pairs in the cascade, and, upon its being turned orig can cause an automatic operation of another of the previous trigger pairs in the cascade. By separating the feed-back circuits and utilizing the on and off condition of the last trigger pair of the cascade and by providing suitable isolation resistors in conjunction with the feed-back circuits, the operating characteristics of the accumulator are improved, and rectiiiers or decoupling units of the semi-conductor or barrier layer type have lower back impedane-e, such as germanium crystals, can be used, thereby eliminating the need for using diodes as rectiers or decoupling units. The trigger pairs of the cascade and the transfer mechanism can readily be preset to starting or zero condition by selectively causing a tube in each of the trigger pairs to be made to conduct by a preset circuit.

The data represented by the combinations of on and o conditions of each denominational order is read out by the readout and digitrnaniiesting means, which includes a motor-driven sensing switch and digit-manifesting ymeans. The manifesting means is arrested in different digit-manifesting positions by control means controlled by the sensing of diiferent potentials at points in a resistor network to. which different combinations of potentials are applied according to the on and olf condition of the cascaded trigger pairs, their being ten points, of which onlir that point Will have a distinctive potential which corresponds to the digit represented by the par- The connectionsv tcular combination of the on and off conditions of trigger pairs of the denomination. Inasrnuch as the potentials of the points in the resistance network are derived from the cascaded trigger pairs, the control means, which controls the position of the digit-manifesting means and the sensing switch and which has the potentials of the points of the network applied thereto by the sensing switch, has a compensating means to insure 'against misoperation due to variations in potentials applied to the cascaded trigger pairs. This compensating means makes the operation of the readout and digit manifesting means very stable and insensitive to variations in supply potentials.

It is an object of the invention to provide an improved electronic accounting machine having a controlled impulse-generating means for producing strong signals to be utilized for making simultaneous entries in desired ordersof a simplin :y

impaired when they are switched simultaneously to a plurality of denominational output conductors.

A further object of the invention is to provide an accumulator for counting in the decimal notation and having, for each denomination, four electronic devices connected in a circuit for representing the digits of the notation in combinational form, the circuit being arranged to allow greater latitude in the choice of components.

A further object of the invention is to provide a counting circuit utilizing, for each denominau tion, four electronic devices connected in cascade and having improved feed-back circuits in which decoupling devices having lower back impedance can be used.

A :further object of the invention is to provide a counting circuit made up of four cascaded trigger pairs. each pair being operable to an on condition and to an off condition, and utilizing the turning orf the fourth trigger pair of the cascade to on condition to send a feed-back pulse to one of the previous trigger pairs of the cascade operation thereof and utilizing the turning of the fourth trigger pair to off condition to send a feed-back pulse to another of the previous trigger pairs of the cascade to cause an operation thereof.

A further object of the invention is to provide a means forl indicating amounts standing inan accumulator and to provide compensating means in the controls for the indicating means to compensate for variations in voltage applied to the accumulator.

With these and incidental objects in view, the invention includes certain novel features of construction and combinations of parts, a preferred form or embodiment of which is hereinafter described with reierence to the drawings which accompany and form a part of this specication.

Of the drawings:

Figs. l-A and l-B together show a circuit diagram of an impulse generator and fthe controls therefor.

Fig. 2 shows a circuit diagram of the units denominational order of the accumulator, including tens transfer means and the coupling device through which entries can be made from the impulse generator of Figs. l-A and 1-B, and also shows digit-manifesting means for making apparent the digit set up in the accumulator.

Fig'. 3 shows a circuit diagram of the tens denominational order of the accumulator and the digit-manifesting means therefor but includes controls for the coupling device through which entries can be made from the impulse generator of Figs. l-A and l-B and from Ithe transfer means of Fig. 2.

In order that the invention may be explained more fully, a preferred embodiment of the invention will be described, in which description values of potential and circuit elements, such as resistors and capacitors, will be given and types of tubes will be specified. it is not intended, however, to limit the invention to the embodiment described nor to limit the circuit values and tube types to those specied, because these are merely selected as illustrative. 1t is obvious that other potentials and/or other similar tube types can be used and the circuit values of resistance and capacitance can be adjusted to maintain the proper relation between the various parts of the circuits. Throughout the circuit diagrams, the heater elements for the tubes are shown conventionally.

Impulse generator The impulse generator is capable o1 generating impulse trains containing different numbers oi impulses corresponding to the digits of the notation in which computations are to be made, and is capable of sending the required number of impulses over one or more output conductors according to the digits desired to be entered into the various denominations of the accumulator. The impulse generator and its controls are shown in Figs. l-A and l-B.

A multi-vibrator type oscillator consisting or' tubes il and l2 (Fig. l-A) is provided to drive the impulse generator and to coordinate the operation on the tens transfer means of the accumulator with the digit entries. These tubes have their anodes I3 and it connected over points l5 and l5 and resistors il" and i8, of 22,000 ohms each, to conductor i9, which extends to terminal 20, to which a potential of +250 volts is applied. The cathodes 2l and 22 of these tubes are grounded. The grid 23 of tube Ilis coupled over capacitor EQ, of 50 micro-microfarads, to point ES in the anode circuit of tube l2 and also is connected to ground over a lmegohm resistor 25. Similarly, grid 25 of tube i2 is coupled over capacitor 2, of 50 micromicrofarads, to point i5 in the anode circuit of tube Il and also is connected to ground over resistor 23 or" 1 megohm. While tubes il and I2 are shown, and function, as two separate tubes, they need not be separate but can be the two sections of a single tube such as may be purchased from Radio Corporation of America under type designation 12AU7. With the values given, and using the 12AU7 type of tube, the oscillator will oscillate at about 7,500 cycles per second, and points as l5 and I6 will make a like number of positive potential excursions.

Point i@ is coupled over a capacitor 3i) of 250 micro-microfarads to grid 3! of a driving impulse generating tube 32. Tube 32, which is shown as a separate tube but which preferably is a half of a twin triode, such as a tube sold by Western Electric Company under the type designation 2G51, is normally biased to cut-o by having its grid 3i connected over a resistor 33 of 150,000 ohms and Over conductors 34 and ,35 to terminal 36, to which -30 volts is applied, and is allowed to conduct momentarily each time the potential of point IS becomes suiciently positive in the operation of the oscillator to overcome the negative bias on the grid 3 l.

Tube 32 has its anode 31 directly connected t the conductor 19, to which +250 volts is applied, and has its cathode 38 connected to ground by a relatively low impedance circuit including point 39 and resistor 40 of 4,700 ohms.

With the values given, a positive potential impulse will be produced at point 30 each time tube 32 conducts momentarily, and these impulses are used to cause the sequential operation of a chain of priming tubes and to drive the impulse-trainproducing tubes.

The chain of priming tubes (Figs. l-A and l-B) utilizes gaseous tetrodes, such as tubes sold by General Electric Company under type designation (iL-5653, and includes a start tube and a priming tube for each ol the digits "1 through 9.

The start tube (Fig. 1-A) has its anode 5 connected directly to an anode potential supply conductor 45, which normally has a potential of +125 volts supplied thereto from point di in the cathode circuit oi an extinguishing t8.

The control grid 50 of the start tube is normally biased to prevent conduction in the tube by being connected over resistor 50, of 47,000 ohms, point i, and resistor 52 of l megohm to terminal 53, to which a potential of 30 volts is applied.

The cathode 60 of the startube given a potential slightly more negative than ground when the tube is non-conducting. rThis potential is obtained by connecting the cathode at point 6I in a resistance-capacitance network eX- tending from point G2 on conductor 03, to which a potential of 108 volts is applied at terminal 64, over resistor S5 of 1.8 megohins, point B6, resistor 67 of 1.6 megohms, point 68, resistor 69 of 15,000 ohr 1s, point 6I, and resistor 70 of 22,000 ohms to ground. Point 68 in this circuit is coupled to ground over a capacitor 'il of 1,000 micro-microfarads. When conduction occurs in the start tube, its cathode 60 will also be conductively coupled to the anode 45, and its potential will change from slightly negative to positive with respect to ground.

The auxiliary or shield grid 'i2 of the start tube is connected to the cathode 00 and will have the same potentials as the cathode.

The start tube is the first tube in the chain and is followed by the 9, "8, 7, 6, 5, 4, 3, 2, and l priming tubes in that order. The circuits for the various priming tubes are similar and will be clear from an explanation or the circuits for the 9 priming tube (Fig. l-A

The anode 'I5 of the 9 priming tube is connected directly to the anode potential supply conductor 46.

rihe auxiliary or shield grid 75 of the 9 priming tube is connected over resistor 'i1 of 47,000 ohms, point 18, and resistor 19, of 1 megohm, to negative potential supply conductor 80, which is connected to terminal 53 and has a potential of -30 volts applied thereto. The auxiliary grid 'IS is also coupled over point 'I8 and capacitor I4 of micro-microfarads to a driving impulse input conductor 13, which connects over point 4| to point 39 in the cathode circuit for tube 32 and receives a positive driving impulse of about 150 volts each time tube 32 conducts momentarily.

The control grid 8l of the 9 priming tube is connected to point 66 in the cathode potential supply circuit for the start tube and, with the start tube non-conducting, has a normal negative bias sumcient to prevent the 9 prima ing tube from lbecoming conduct-ing even though driving impulses are applied to the auxiliary grid. When the start tube has been fired and is conduct-ing, the positive potential oi its cathode 30 will be reflected on the potential of the control grid Sl of the 9 priming tube and will reduce the negative bias t. ereon to a point where the tube can become conducting in response to a driving impulse impressed on its auxiliary grid.

The cathode 82 of the 9 priming tube is supplied with potential from a resistance-capacitance network, like the one for the start tube, which extends to ground from the negative potential supply conductor 53.

Each of the priming tubes for the digits 8 to l inclusive has an anode potential supply circuit and a cathode potential supply circuit like those for the 9 priming tube, each has a negative potential supply circuit for its auxiliary or shield grid and capacitance coupling from its auxiliary grid to the driving impulse input conductor 73, similar to those described above in connection with the 9 priming tube, and each has its cont-rol grid connected to the cathode potential supply circuit of the preceding tube in the chain to be primed thereby upon conduction occurring in the preceding tube.

It is to be noted that the driving impulses from tube 32 are not eiective to cause an unprimed tube to conduct; onsequently the impulses will be ineffective on any of the priming tubes of chain until the St-art tube has been and primes the 9 priming tube. The start tube is iired in the following manner. Point 5i in the control grid circuit for the start tube is coupled over conductor 85, capacitor of l0 micro-microfarads, and point 8'! to the motor bar or start key switch 88, which is normally open but which can be closed to connect point 0l to conductor 39, which extends to terminal 00, to which a potential of +250 volts is applied. When the motor bar or start key switch B is closed and the +250 volts is applied to capacitor 85, a positive impulse will be impressed on the control grid 49, which impulse is suihcient to lire the start tube, thereby priming or conditioning the 9 priming tube so that it can respond and be fired by the next driving impulse on conductor '13. Point 87in the motor bar or start key control circuit is connected to ground over resistor of 47,000 ohms to provide a discharge path through which capacitor 8B can be discharged when the motor bar or start key switch 88 is opened.

Each oi' the priming tubes, when, red, will prime the next tube of the chain, so that it will be fired by the next driving impulse. Accordingly, after the start tube has been fired by the closing of the start key switch 80, the next nine driving impulses will fire the tubes of the priming chain one after another.

The tubes of the chain, being gas tubes, will remain conducting, once they are fired, until they are extinguished by the operation of an extinguishing means which includes the tube 4S. This operation of the extinguishing means takes place after the last tube in the chain has been red and has effected its control, at which time all the tubes of the chain are rendered non-conducting.

Since the priming tubes oi the chain are lred in sequence by successive driving impulses and are all extinguished at the same time, the several tubes will be conducting for progressively longer periods of time; that is, the 9 priming A:2G51 type of tube.

tube will be conducting longer than the 8 tube, the 8 tube will be conducting longer than the "7 tube, etc.

Each priming tube controls a related impulsetrain-producing tube by priming that tube as long as the priming tube is conducting, and enables the driving impulses from tube 32, which are impressed continuously on the impulse-trainproducing tubes, to become eiective to operate the tube and produce a train of impulses corresponding in number to the digit to which the priming tube is related. For example, the impulse-train-p-roducing tube related to the 9 priming tube will produce a train containing nine impulses, the imp-ulsetrain-producing tube which is related to the 8 priming tube will produce a train of eight impulses, etc., the impulse-train-producing tube related to the l priming tube producing one impulse.

The circuits and controls for the-impulsetrain-producing tubes are similar, and it is believed that an understanding of the operation of all these tubes will be clear from a description of the operation of one of them.

The impulse-train-produ-cing tube for producing a train of nine impulses is representative and is shown at in Fig. l-A. This tube is shown as a separate triode, but preferably it is one half of a twin triode, such as the above-mentioned The tube has its anode |0| connected directly to conductoni, which, as explained earlier herein, has a potential of +259 volts applied thereto at terminal 20. The cathode |02 of the tube is connected over point |03 and resistor |00 of 2,200 ohms to point |05 on potential supply conductor |00, which has a potential of +130 volts applied thereto at terminal |01. This anode-cathode potential supply circuit has a very low impedance and will produce a strong positive impulse of about 55 volts at point |03 each time the tube |00 is operated.

Control grid |09 of tube |00 is connected over point H0 and resistor of 100,000 ohms to point ||2 in the cathode potential supply circuit for the "9 priming tube. Point ||0 in the grid circuit is also coupled over a capacitor ||3 of 250 micro-micrcfarads to the driving impulse input conductor H0, which is connected over point 4| to point 39 in the circuit of the driving impulse generating tube 32. is not conducting, point l2 in its cathode circuit and consequently grid |09 of the impulsetrain-producing tube |00 will be slightly negative with respect to ground, and, since the cathode |02 is at a potential of +130 volts, the tube |00 will be biased suiciently past cut-off that the driving impulses on conductor HZ will be ineffective to cause conduction in tube |00.v However, when the "9 priming tube is conducting and its cathode has become positive, point |I2 willbecome more positive and reduce the bias on tube |00 to a point where the driving impulses on conductor H0 will be effective to cause momentary conduction in the tube |00 and thereby provide positive impulses at point |03. Capacitor H5,

which is similar to capacitor 'H in the cathode' cir-cuit of the start tube, delays the application of the priming potential to grid |09 suiciently that the impulse which fires the "9 priming tube will have passed before the tube |00 is ready for operation. The iirst driving impulse that will be effective on tube |00 will be the same one that res the 8 priming tube.

Conductor is connected to point |03 and will have the positive impulses at point |03 im- Whenthe 9 priming tube pressed thereon. Switch |2 I, which can be closed by a 9 digit key or any other switch-operating device in the units denominational order, will connect the conductor |20 to a units denominational output conductor |22. Similarly, a switch |23 can be closed by a 9 digit or other switchoperating device in the tens denominational order to connect the conductor |20 to a tens denorninational output conductor |24. While only two sets of switches and two denominational output conductors have been shown, it is obvious that as many can be provided as are needed according to the denominational capacity desired.

Each of the other impulse-train-producing tubes has connections similar to the ones given above and is capable of producing the required number of impulses which can be switched to output conductors |22 and |24 as desired. The use of the low impedance source of impulses allows the impulses to be switched to a plurality of output conductors without impairing the ability of the impulses to operate the accumulator.

The driving impulse, which follows the driving impulse which res the "1 priming tube, Will be effective on the primed impulse-train-producing tubes to cause the last impulse in each train to be generated and will be effective on the primed tube |00 (Fig. l-B) to cause that tube to operate and generate the impulse for eiecting an entry of the digit l in the accumulator. This impulse which is generated by the tube |00 goes out over conductor |05, from which it can be switched to output conductors, as |22 and |24. The impulse on conductor |05 also is used to opferat-e the extinguishing means to cause the tubes of the chain to be extinguishedand remove the priming from the impulse-train-producing tubes.

As explained earlier herein, the anodes of the start tube and the priming tubes l to 9 are connected to conductor 00. The potential of conductor t0 is derived from an impedance network having one branch which extends from point on -l-voltconductor 03, over resistor |5| of 56,000 ohms, point |52, and to ground over resistor |53 of 500,000 ohms, and having another branch which extends from point |52, over point 0l, to the cathode |54 of the eX- tinguishing tube 00, and through the tube whose anode |55 is directly connected to conductor 89, to which a potential of +250 volts is applied. IIube 48 is preferably of the type sold by Radio Corporation of America under the type designation 6AQ5, and, by varying the impedance thereof, the potential applied to conductor 06 and the anodes of the tubes of the chain can be controlled.

Normally, the potential on the control grid |55 ci tube 40 is such that the tube will conduct suiliciently to give its cathode |50 and the conductor 06 a potential of +125 volts. However, when the potential on the grid |55 of tube 00 is modified to increase the impedance of the tube so that less current flows therethrough, the cathode potential and that of conductor it will become less positive and even may become negative with respect to ground, thereby causing the anode potential of the conducting tubes of the chain to drop below their cathode potential and the tubes to be eX- tinguished.

The potential of grid |50 is controlled from a resistor |00 in the anode circuit of a twin triode control tube |011, which is preferably of the type sold by Radio Corporation of America under the type designation 12AX'7. The anodes |02 and |63 :are connected together and over the resistor 9 |60 of 470,000 ohms to conductor 00, to which a potential of +250 volts is applied.

The cathode of one of the triodes of tube |6| is connected directly to terminal |05 and has a potential of +65 volts applied thereto. The cathode |50 of the other triode of tube |0| is connected directly to terminal |01, to which a potential of 08 volts is applied.

Grid |10 cooperates with the anode |03 and the cathode |04 to determine the normal potential applied to grid |50 of tube 4S. Grid |10 is supplied with the required potential from an adjustable tap |1| on resistor |53.

Grid |12 cooperates with the anode |02 and the cathode |00 of tube |6| and is effective therethrough to modify the potential of grid |50` of extinguishing tube 48 to.increase the impedance of this tube and cause the extinguishing of the tubes of the chain.

The impulse which is generated by tube |40 and is applied to conductor |45 is impressed on grid |.2, either directly or through an impulsewidening device, and will cause the extinguishing of the tubes of the.. chain. In the disclosed embodiment, the impulse on conductor |45 will be applied through an impulse-Widening device. conductor |45 is coupled through a capacitor |15 of .005 niicrofarad to the anode |15 of a diode |11. Preferably this diode is one half of a twin diode tube of the type sold by Radio Corporation of America under the type designation GAL-5. Anode |16 of the diode |11 is also connected over resistor |18 of 39,000 ohms and conductor |10 to conductor 03, which has a potential of 108 volts applied thereto. Cathode |80 of the diode is also connected to conductor |10 over a resistor |8| of 1 megohm in parallel with a capacitor |02 of 250 micro-microfarads. Point |83 in this circuit is connected over resistor |84 of 200,000 ohms to the grid |12 of the control tube.

A positive impulse on conductor |45 will be effective, through the low impedance of the diode |11, to charge capacitor |02 and make point |33 and the grid |12 connected thereto more positive. Since the discharge paths for the capacitor |82 are through the resistor |8| of l megohm and the high back impedance of the diode 11, the grid |12 will remain positive for a longer time than that required for the impulse on conductor E45.

When grid |12 becomes more positive and more current ows through resistor |50, grid |50 will become more negative and increase the impedance of tube 40, thereby to reduce the anode potential applied to the tubes of the chain sufficiently to cause them to be extinguished.

The impulse-widening means, 'while not necessary, provides an additional factor of safety in the operation of the device, because it allows the anode potential for the tubes of the chain to be depressed for a longer period of time than ref' quired to deionize them and insures that all tubes of the chain will be extinguished.

Accordingly, for each operation of the tart tube, impulse-train-producing tube |00 will produce a train of nine impulses on conductor |20; tube 30 will produce a train of eight impulses on conductor |3|; tube |52 will produce a train of seven impulses on conductor |33 tube 04 will produce a train of six impulses on conductor |35; tube |30 will produce a train of ve impulses on conductor 131; tube |38 will produce a train of four impulses on conductor |30; tube |00 will produce a train of three impulses on conductor v14| tube |02 will produce a train of two impulses on conductor |43; and tube |44 will produce an 10 impulse on conductor |45. Each impulse train is common to the plurality of denominational output conductors, and the trains of impulses can be switched to the output conductors according to the digits desired to be entered into the various denominations of the accumulator.

If no entry is to be made in any denominational order of the accumulator, a zero switch, as 45, for that order is closed to connect the related output conductor to conductor |05 over a resistor |01 of 2,200 ohms to provide a comparable low impedance loading for the output conductor when it is not otherwise connected to an impulse-trainproducing tube.

It should be noted that the start tube and its controls will allow only one impulse-trainpr-oducing operation of tubes |00, |30, |32, |34, etc., for each closure of the motor bar or key switch 08, because, as long as the switch remains closed, capacitor will remain charged, and no additional firing impulses can be applied to the control grid 49 of the start tube.

The impulse generator also includes a transfer-effecting impulse-generating means which is controlled from the oscillator and is timed to cause transfer entries to be made without interference with digit entries in the accumulator.

The transfer-effecting impulse-generating tube 00 (Fig. l-A), which preferably is one half of the above-noted 12AU7 type of tube, has its anode i0: connected over point |02 and resistor |93 of 22,000 ohms to conductor l0, to which is applied a potential ci +250 volts, and has its cathode |013 directly connected to ground. Control grid 505 normally biases the tube to cut-off by being connected over resistor |06, point |01, and resistor |00 to conductor 35, to which a potential of -30 volts is applied at terminal 36. Control grid |05 is also coupled from point |91 over capacitor |09 ration of the oscillator.

Whenever the tube conducts, a negative potential drop of about volts occurs at point |02 in its anode circuit, and these potential drops are applied over conductor 200 (Figs. l-A and l-B) and resistor 20| of 47,000 ohms to the transfer means of the units denominational order of the accumulator and over resistor 202 of 47,000 ohms to the transfer means of the tens denominational order of the accumulator. The negative impulses which are impressed on conductor 200 will occur' during the intervals between the positive impulses on Bthe denominational output conductors |22 and |24 and are effective to cause transfer entries to be made in the accumulator without interfering with the digit entries. The manner in which the transfer-effecting impulses cause the operati-on of the tens transfer means will be explained more fully hereinafter.

Accumulator Two denominational orders of the accumulator are shown in Figs. 2 and 3.

Each denominational order includes an electronic coupling device, an electronic tens transfer means, and a plurality of interrelated electronic devices capable of accumulating in the decimal notati-on and representing, in combinationai form, the units digit of said accumulation.

Fig. 2 shows the units denominational order of the accumulator.

rThe coupling device is shown as a twin triode,

tube 220, preferably of the above-noted 2G51, type, though, as will appear later, only one of the tri-odes is utilized in the units order, the one for coupling the order of the accumulator to the corresponding denominational output conductor of the impulse generator. In the embodiment shown, there are no tens transfer entries to be made in the units denominational order of the accumulator, and accordingly the other of the triodes is not used to control entries therein.

Tube 220 has both of its anodes 22| and 222 connected together and over point 223 and resistor 224 of 47,000 ohms to conductor 225, to which a potential of +250 volts is applied at terminal 226, and has its cathodes 221 and 223 and shield 2|9 grounded.

Grids 230 and 23| have biasing potential supplied thereto from a biasing potential supply circuit which extends to ground from conductor 232, to which a potential of 75 volts is applied at terminal 233, over resistor 234 of 100,000 ohms and resistor '235 of 47,000 ohms, grid 230 being connected over point 236, and resistor 231 of 47,000 ohms to point 230 in the bias potential supply circuit and grid v23| being likewise connected over a resistor 240 of 47,000 ohms to point 24| in the bias potential supply circuit. Point 24| is connected to ground over a stabilizing capacitor 242 of 500 micro-microfarads. The potential supplied to the grids normally biases both halves of the tube to cut-off.

The units denominational output conductor |22 (Figs. l-A, l-B, and 2) of the impulse gen erator is coupled over capacitor 243 of 250 micromicrofarads to grid 230, which controls conduction between anode 22| and cathode 221 of the left triode in the tube l220. Whenever an impulse of an impulse train is impressed on conductor |22, it will be effective to cause the triode, which is controlled by grid 230, to conduct and produce a potential drop at point 223 due to resistor 224 in its anode circuit.

In the units denomination of the disclosed embodiment of the accumulator, grid 23|, which controls the right-hand triode of the tube 220, will have no impulses applied thereto, so this triode of the tube will remain biased to cut-off.

The potential drops which are produced at point 223 when conduction occurs in the tube are used to provide negative impulses to operate the interrelated devices of this denominational order for accumulating amounts. The interrelated devices consist of four trigger pairs connected in cascade and with selective feed-back circuits to enable them to accumulate values in the decimal notation and to represent the various digits of the notation by diierent combinations of on or off conditions of the trigger pairs.

As is well known, an electronic device known as'a trigger pair consists of a pair of electron discharge tubes having interconnections therebetween to control their operation so that, at any given time, one of the tubes is conducting. and the other tube is non-conducting, and the act of changing the conducting condition of one of the tubes will cause the conducting condition of theother of the tubes of the pair to change. With the circuit constants to be given herein, the 'trigger pairs' will be relatively insensitive to positive impulses but will respond to negative impulses, so that a negative input impulse apy may be made up of two separate tubes; however, in order to provide a more compact device, each of the cascaded trigger pairs in the disclosed embodiment of the invention is formed by interconnecting the two halves of a twin triode type of tube, preferably of the aforementioned 2G51 type.

The first trigger pair of the cascade will be that marked A, the second trigger pair will be B, the third trigger pair will be C, and the fourth and rlnal trigger pair of the cascade will be D. The trigger pairs will be considered in their on `condition when the left triode of the trigger pair is conducting and in their off condition when the left triode of the trigger pair is in non-conducting condition. The manner in which the trigger pairs represent the various digits can be seen from the following table, in which "O designates the oir condition and X designates the on condition of a trigger pair.

| Digit A B l o D X o o X o o o X o o X o X X O X X o o X X o X X X X X X X X Trigger pair A is the first trigger pair of the cascade and is operated by impulses impressed thereon from the coupling device, tube 220. The left triode 245 of the trigger pair has its anode 246 connected over resistor 241 of 47,000 ohms to the +250-volt conductor 225 and has its cathode 248 connected directly to ground. Similarly, the right triode 250 of the trigger pair has its anode 25| connected over resistor 252 of 47,000 ohms to the +250-volt conductor 225 and has its cathode 253 directly connected to ground.

Grid 255 of the left triode 245 is connected to a negative bias supply over point 256, resistor 251 of 150,000 ohms, `and conductor 232, to which a potential of volts is applied at terminal 233, and also is coupled to the anode 25| of the right triode 250 over a network containing resistor 258 of 200,000 ohms shunted by resistor 250 of ohms in series with capacitor 260 of micro-microfarads. In a similar manner, the grid 263 of the right triode 250 is connected to the negative bias supply over point 264 and resistor 265 of 150,000 ohms to conductor 260,

" which is connected over a reset switch 261 to conductor 232. Grid 263 is also coupled to the anode 246 of the left triode 245 over a network containing resistor 268 of 200,000 ohms shunted by resistor 269 of 100 ohms in series with capacitor 210 of 150 micro-microfarads.

Points 256 and 264 in the bias supply circuits for the grids 255 and 263 are coupled, respectively, over capacitors 215 and 216 of 25 micromicrofarads to a conductor 211, thence over resistor 218 of 47,000 ohms to the point 223 in the anode circuit of the coupling device, tube 220.

With the circuit constants given, trigger pair A will be responsive to negative impulses and will reverse the conducting status of the triodes therein each time a negative impulse is impressed on the grids of the triodes. Accordingly, the trigger pair will reverse its conducting status each time the coupling device responds to an impulse from the impulse generator and sends a negative impulse to the pair.

Trigger pa-ir B, which is the second trigger pair of the cascade, is operated to reverse the conductive condition of the triodes therein in response to an impulse impressed thereon from trigger pair A when that pair goes from its on condition to its 01T condition. Trigger pair B is also operated from its oli condition to its on condition in response to a feed-back irnpulse from trigger pair D in a manner to be explained more fully hereinafter. The anodes 200 and 201, respectively, of the left triode 282 and the right triode 203 of this pair are connected over resistors 204, and 285 of 47,000 ohms, respectively, to the |25Gvolt conductor 225, and the cathodes are connected to ground.

Grid 286 of the left tiode 282 is connected to negative bias supply by being connected over point 281 and resistor S of 150,000 ohms to conductor 256, and is also coupled to the anode 28! of the right triode 233 over a network containing resistor 200 of 200,000 ohms shunted by resistor 29| of 100 ohms in series with capacitor 292 of 250 micro-microfarads. Grid 205 of the right triode 233 is connected to the negative cias supply over resistor 2.35 of 47,000 ohms, point 291, resistor 203, of 150,000 oliros, and conductor 26S. Grid 205 is also coupled to the anode 280 of the left triode 282 over resistor 200 and resistor 299 of 200,000 ohms, resistor 200 being shunted by resistor 300 of 100 ohms in series with a capacitor 30! of 250 micro-microfarads.

' Point 237 in the bias supply circuit to grid 280 is connected over resistor 301i or 47,000 ohms and capacitor 305 of rnicio-niicroiarads to conduetor 300, which extends to the anode 255 of the right triode 250 of trigger pair A. Point 20T in the plas supply circuit for grid 205 is also coupled to conductor over a capacitor 301 of 25 micro-microiarads. Each time tri ger pair A is operated to its oil condition and the right triode '2E-0 thereof conducts, a negative impulse will 'ce sent over capacitors 04 and 301 to the grids 285 and 205 of the trigger pair B to cause a reversal of the conducting condition of the triodes therein.

Resistors 200 and d are isolation resistors, which are operative to control the effect of the feed-baci: impulse on trigger pair B and also cooperate With the rectier in the feed-hack circuit to enable rectiers of the semi-conductor or barrier-layer type lia-ying lower back impedance to be used and still prevent impulses from trigger pair B from causing improper operation of trigger pair D. The manner in which these resistors are operable to perform the alcove functions will be explained more fully hereinafter, when the feed-baclt circuit and its operation are explained.

Trigger pair C, which is the third trigger pair of the cascade, is operated to reverse 'the conducting condition ot the triodestherein in response to an impulse from trigger pair B when that pair goes irorn its on condition to its "oii condition. Trigger pair C is also operated from its cil condition to its on condition in response to a feed-back impulse from trigger pair D in manner to ce explained more fully hereinafter. The circuit arangeinent and circuit constants for trigger pair C are identical Wit-h t-liose of trigger pair ES will not ce repeated.

Trigger pair which is the last trigger pair in the cascade, is operated by inipulses impressed 'i thereon from trigger pair C and is effective to send feed-back impulses selectively to trigger pairs B and C and to send an impulse to a tens transfer means to prepare it for a tens transfer operation.

The left triode Sie of trigger pair D has its anode 3H connected over point 3i2, resistor 3i3 of 22,000 ohms, point Shi, and resistor SES of 22,000 ohms to the +250-volt conductor 225 and has its cathode connected to ground. in a like manner, the right triode 2HE has its anode 3H connected over point Sii, resistor tie of 22,000 olinis, point 320, and resistor 0.2i or 22,000 ohms to the -{-250volt conductor 225, and has its cathode connected to ground.

Grid 325 of the left triode 2li? is connected to the negative bias supply over point 320, resistor 32"! of 150,000 ohms, and conductor 232, and is also coupled to the anode Si? of the right triode 3|?) over resistor 320 00200000 onins, shunted cy resistor oi ohms in series with capacitor of 250 micro-microiarads. Similarly, the grid 335 of the right triode dit is connected to the negative bias supply over point 335, resistor 33"! or" 150,000 ohms, and conductor 20?. Grid 335 is also coupled to the anode 3H oi the left triode Sill over resistor 333 of 200,000 ohms, shunted by resistor 339 of 100 ohms in series with capacitor 300 of 250 inicro-1nicrofarads- Points 320 and 330 in the olas potential supply circuits ci grids and 335, respectively, are coupled over capacitors 3M and 302 of 25 micromicrofarads to conductor which extends to the anode of the right triade of trigger pair C and enables a negative impulse to he impressed on the grids 325 and each time trigger pair C turns from its on condition to its ofi condition.

A feed-pack circuit extends from point- 320 in the anode circuit for the right triode @it of trigger pair D, over capacitor 305 of micrornicrofarads, 3&0, rectifier 3M, which is, tor example, a germanium crystal diode of the type sold by Western Electric Company under the type designation Vv'ElOB, and conductor 43 to the grid 205 of the right triode 283 of the trigger pair B. The rectifier 3M is oriented to pass negative feed-sack pulses from the trigger pair D to the trigger pair B and to prevent negative impulses en grid from being transmitted to trigger pair i3. Point 3130 in. the feed-back circuit is connected to ground over a resistor 312.9 of ll'l0,000 olinis to provide a leakage path to discharge capacitor 305.

The above feed-back circuit and its related circooperate in the following manner to malte it possible to use crystal diodes instead of vacuum tube diodes in the feed-back circuit. In the circuit arrangement shown, the feed-back impulse is applied directly to grid 205, and the isolation resistors 220 and 304 are in series between the feed-hack c` 1cuit and grid 285 ci the leit tricde 282. These resistors reduce materially the eiect of the negative feed-baci: impulse on grid 20E and the triode 202 controlled thereby. By thus attenuating the eect of the reed-back impulse on the left triode, the eiiect of the potential cna-nge of anode will be greater and a smaller-ainplitu-:ie feed-baci: impulse applied directly to the grid 235 of the right tiiode Will be as erective to reverse the operation of the pair as t .e largeamplitude impulse applied in common to the triodes of the pair from the preceding trigger pair of the cascade. This enables the feed-back impulse to be taken from the midpoint of the resistance in the anode circuit for the right triode 310 of trigger pair D, at point 320, instead of l5 directly from the anode at point BIB. With the feed-back impulse taken from point 32! by connecting the feed-baci: circuit thereto, resistor 3|!) is placed in series between the feed-back circuit and the anode Sil of the triode 3dB and attenuates the eect on anode Eli and grid 325, coupled thereto, of any impulses transmitted from trigger pair B. Similarly, resistor 295 in the circuit to grid 2s?) of the right triode of trigger pair B will attenuate impulses applied to the grid 295 from anode 2.8i! of the left triode 282 of trigger pair B, and also from anode 25| of right triode 258 of trigger pair A, and, consequently, will attenuate the effect of impulses from these sources on the feed-back circuit, which is connected directly to grid 2&5. The above attenuating effects of resistors 295 and 359 are cumulative and are effective in the circuitarrangement to enable crystal rectiers of the semi-conductor or bar rier-layer type, which can be much smaller but which have lower back resistance than vacuum tuberectiflers, to be used in the feed-back circuit without causing improper operations to take place.

A similar feed-back circuit extends from the midpoint Si i of the anode resistance network for the left triode 350 of trigger pair D, over capacitor 355 and rectiiiers 35B, to the grid of the right triode of trigger` pair C, and enables the turning of trigger pair D on to send a negative feed back impulse to trigger pair C to turn it from Lo Ion-! The manner in which the various trigger pairs are operated in combinations to represent digits of the decimal notation will now be explained in an operation in which ten impulses are sent to the denomination to operate it through a complete cycle and return it to starting condition. As shown in the tabulation given earlier herein, the zero or starting condition of the trigger pairs of the denomination is that in which trigger pairs A, C, and D are in off condition, With their right triodes conducting, and trigger pair B is in its on condition, with its left triode conducting. All input impulses to the denomination are applied to the coupling device, tube 220, which in turn applies them to trigger pair A, the first trigger pair of the cascade.

The rst impulse applied to trigger pair A changes it from its orf condition to its on condition, so that the trigger pairs A and B will be on and trigger pairs C and D will be off to represent the digit "1.

The second impulse applied te trigger pair A changes it from on to oli As trigger pair A goes from on to oli it sends an impulse to trigger pair B, which turns trigger pair B from on to oi and triggerv pair B, in going from on to oii`, sends an impulse to trigger pair C to turn it from off to onf At the end of this entry, trigger pairs A, B, and D are oi and trigger pair C is on to represent the digit2.

The third impulse applied to trigger pair A merely changes that pair from ei' to en At the end of this entry, trigger pairs A and C are on and trigger pairs B and D are foi to represent the digit 3.

The fourth impulse applied to trigger pair A turns trigger pair A from on to off and trigger pair A, in turning oi sends an impulse to triggerpair B to turn it from off to on. At the end of this entry, trigger pairs A and D are 01T and trigger pairs B and C are on to represent the digit 4.

16 The fifth impulse applied to trigger pair A merely turns this trigger pair from off to 011, and, at the end of this entry, trigger pairs A, B. and C will be on and trigger pair D will be oif" to represent the digit 5.

The sixth impulse applied to trigger pair A will turn this trigger pair from on to oi and,

in turning from on to oii trigger pair A will send an impulse to trigger pair B to turn it from on" to olii The turning of trigger pair B to oii will send an impulse to trigger' pair C to turn it from on to Off, and trigger pail' C, in turning to ofi Will in turn send an impulse to trigger pair D to turn it from oi to 011. When the trigger pair D is turned from off to on, a feed-back impulse is sent from the left triode of trigger pair D to the right triode of trigger pair C to cause trigger pair C to be turned on. At the end of this operation, trigger pairs A and B will be off, and trigger pairs C and D will be on to represent the digit 6.

The seventh impulse applied to trigger pair A will merely turn trigger pair A from off to on," and, at the end of this entry, trigger pairs A, C, and D will be on and trigger pair B will be orf to represent the digit 7.

The eighth impulse applied to trigger pair A will turn trigger pair A from on to off, and the turning of trigger pair A ofi sends an impulse to trigger pair B to turn trigger pair B from off to on. At the end of this entry, trigger pairs B, C, and D will be on, andY trigger pair A will be oli to represent the digit 8.

The ninth impulse applied to trigger pair A will merely turn trigger pair A from oli to 011, so that, at the end of this entry, all the trigger pairs will be on to represent the digit 9.

The tenth impulse which is applied to trigger pair A will turn trigger pair A from its on condition to its off condition, and trigger pair A, in turning to its off condition, will send an impulse to trigger pair B to turn it from on to offf Trigger pair B, in turning to its "oif condition, will send an impulse to trigger pair C to turn it from on to ofi and trigger pair C, in turning ofi'j Will send an impulse to trigger pair D to turn it from on to oft As trigger pair D is turned from on to off, the other feed-back circuit becomes effective, and an impulse is sent from the right triode SIS thereof to the grid 295 of the right triode of trigger pair B to turn the trigger pair B from oi to on." At the end of this entry, the trigger pairs A, C, and D will be in ofi condition, and trigger pair B will be in on condition, which is the condition in which they were at the beginning of the entry of the ten impulses.

It is seen, therefore, that the cascaded trigger pairs of the denomination can be operated in combinations of on and off conditions to rep# resent the digits 1 to 9 and 0, and can be returned to starting condition upon the application of ten impulses to the rst trigger pair of the cascade.

Fig. 3 sho-ws the coupling device, the cascaded trigger pairs A, B, C, and D, and the tens transfer means of the tens denominational order of the accumulator. The tens denominational order is representative of all intermediate orders of the accumulator. The highest denominational order of the accumulator would be the same as the intermediate orders except that it would not be required to control a transfer means to transfer values to a higher order. Except for an additional control of the coupling device by which 17 tens transfer entries can be made from a lower order, the circuits of this figure are the same as those for the units denominational order shown in Fig. 2. Where the circuit constants and circuits of Fig. 3 are the same as those of Fig. 2, the description of them will not be repeated.

The coupling device for the tens denominational order is a twin triode 360 (Fig 3), similar to the twin triode 220 (Fig. 2). As is the case with the coupling device in Fig. 2, the anodes 36| and 362 (Fig. 3) are connected together and over a resistor 363 of 47,000 ohms to a +250-volt conductor 364, and the cathodes are connected to ground. Grid 365 of the left triode is supplied with negative grid bias from conductor 366, to which -75 volts is applied, and is coupled over capacitor 361, of 250 micromicrofarads, to the tens denominational output conductor |24 of the impulse generator (Figs. 1 and'l-A). The left triode is normally biased to cut-01T but will conduct momentarily when the positive output impulses from the impulse generator are applied to grid 365. Each time this triode conducts, the drop across the anode resistor 363 Will cause a negative impulsel to be applied to the first trigger pair of the cascade to cause an advance in the digit represented vby the operating condition of the cascaded trigger pairs.

*Grid 310 of the right triode of the coupling device is supplied with negative biasing potential from conductor 366 and is coupled over capacitor 31|, of 250 micro-microfarads, to conductor 312, which extends to the transfer means. of the next lower order and receives a positive impulse each time a transfer entry is made from the lower order. Each positive transfer impulse which is applied to grid 310 will cause the right triode of the coupling device to conduct momentarily, which conduction will produce a drop across the anode resistor 363 similar to the one produced .by an impulse from the impulse generator. This drop is applied as a negative impulse to the first trigger pair of the cascade to cause a unit advance in the digit representation of the cascaded trigger pairs.

Tens transfer means Tens transfer means are provided for the accumulator to make an entry of a value of one inthe next higher order of the accumulator each time an order exceeds its capacity. Since the same type of transfer means couples adjacent denominational orders of the accumulator, the operation of the various transfer means will be clear from a description of the operation of the means coupling the units and tens denominational orders of the accumulator.

, The transfer means includes a trigger` pair which is operated from a normal' conducting condition when the related denominational cascaded trigger pairs exceed their digitalcapacity and is effective to cause -an entry in the next higher order when restored to normal condition.

The tens transfer trigger pair (Fig. 2) is shown as being made up of two halves of a twin triode,1tube 315, preferably of the above-mentioned 2C51 type.

:Anodes316 and 311 of 'the left and right triodes of this trigger pair are connected, re spectively, over resistors 318 and 319 of 47,000 ohmsto the +250-volt conductor 225, and the cathodes of these triodes are connected to ground.

Grid 380 of the leftvtriode is coupled to the negative `bias supply conductor 232 over-point .Vil

38| and resistor 382 of 150,000 ohms and also is coupled to anode 311 of the right triode by the trigger connection including resistor 383 of 200,000 ohms, shunted by resistor 394 of 100 ohms in series with capacitor 335 of 250 micro-microfarads. In a corresponding manner, grid 386 of the right triode is coupled to the negative bias supply conductor 266 over point 394 and resistor 381 of 150,000 ohms and also is coupled to anode 316 of the left triode by the trigger connection including resistor 388 of 200,000 ohms, shunted by resistor 389 of 100 ohms in series with capacitor 390 of 250 micro-micro farads. When the accumulator is initially setin op` eration or is reset to zero, the tens transfer trigger pair is set in its normal condition, With the right triode conducting, as will be explained more fully hereinafter when the resetting operation is considered.

When a tens transfer is required, the cascaded trigger pairs of the denomination will cause the tens transfer trigger pair to operate to reverse itsconducting status. This is accomplished in the following manner. As is seenfrom the tabu.-

' lation given earlier herein, the trigger pair D will change from itscn'condition to its off condition only when the digit represented by the cascaded trigger pairs changes from 9 to 0. The drop across anode resistors 3|8 and 32| of the right triode of this trigger pair which occurs when the pair changes from on to oif is applied as a negative impulse to grid 386 of the right triodeV of the tens transfer trigger pair, over conductor 39|, resistor 392 of 47,000 ohms, capacitor 393 of 25 micro-microfarads, and point 394, and Will cause the tens transfer trigger pair to be operated from its normal condition and reverse the conducting statusof its triodes.

As explained earlier herein in connection with the impulse generator, the transfer-effecting impulse-generating Atube |90 (Fig. l-A) is driven from theoscillator and produces negative potential drops which are transmitted over conductor 200 and resistors, as 20| and 202, during the intervals between the occurrence of positive impulses on the denominational output conductors. as |22 and |24.

The drop transmitted over resistor 20| is transmitted further over conductor 395 (Figs. 1-B and 2), capacitor 396 of 25 micro-microfarads, and point 38| and is impressed as a negative impulse ongrid 380 of theleft triode to cause the trigger pair to reverse its conducting status andreturn to its normal condition if it had been operated from normal condition by a required tens transfer. If the tens transfer trigger pair is in its normal condition, theleft triode Will already be in non-conducting condition, and the negative transfer-effecting impulses applied to grid v380 will not have any effect on the trigger pair to change the status of conduction of its triodes; but. if the trigger pair has been changed from normal condition due to a required tens carry, then the left triode will be conducting and the negative transfer-effecting impulse will render the left triode non-conducting, and, through the trigger action, Will restore the pair to its normal condition. As the left triode becomes non-conducting., its anode potential becomes more positive, and this potential change is transmitted over conductor 400, resistor 40| of 47,000 ohms, conductor 312 (Figs. 2 and 3), and capacitor 31| to the grid 310 in the right triode of the coupling device. tube 360, of the tens denominational order .to

cause an impulse to be impressed on the cascaded trigger pairs of the tens denominational order to make a unit entry therein.

It is to be noted that, since the transfer entries are effected by impulses which are generated in the intervals between the times when digit-entryeffecting impulses can be generated, transfer entries can be made at any time during or after a digit entry without interfering with the digit entry.

The tens transfer` means, which is controlled from the tens denominational order trigger pair D (Fig. 3), includes the twin triode 402, which has transfer-effecting impulses applied thereto from the impulse generator over conductor 200, resistor 202, conductor 403 (Figs. l-B and 3) and capacitor 404, and which can send a tens transfer signal over resistor 405 and conductor 406 to the next higher or hundreds order of the accumulator when required.

In a similar manner, other transfer means can be controlled from the trigger pairs D of their related orders and can be operated by transfereiecting impulses to cause tens transfer entries to be made in appropriate higher orders.

Resetting In order to 'prepare the accumulator initially to receive entries or to reset it to its zero condition, reset switches, as 261 in Fig.. 2 and 4|0 in Fig. 3, are provided in the negative bias supply circuits for the grids of the right triodes of triggerjpairs A, C, and D and the left triode of trigger pair. B. Momentary opening of the switches will remove negative bias potential from these grids and Will cause the trigger pairs A, C, and D to be set in their off condition and trigger pair B to its on condition.

While separate reset switches as 261 and 4|0 are shown for various denominations, it is obvious that conductors, as 266, for the various denominations could be connected together and over a single Yreset switch to a source of -75 volts.

The transfer trigger pairs are also conditioned bythe operation of the reset switches, which remove ne'gative bias from the grids of the right triodes of these trigger pairs and cause these trigger pairs to be set to their normal position, with the right triode conducting. This control of the transfer trigger pairs from the reset switches insures that these trigger pairs will always be setito ,their normal'condition initially or after a resetting operation, and prevents any improper transfers from being made as a result of changing trigger pair D to its 01T condition'in the initial setting or resetting operations.

Digit-manifesting means vMeans are provided to manifest the digit values represented by the combinations of on and oir conditions of the cascaded trigger pairs of the various denominational orders of the accumulator.

The manifesting means for each of the denominational orders are substantially the same, thatfor thev units denominational order including a digit-manifesting wheel 4| (Fig. 2), a readoutscanning switch 4|2, and a notched element 4|3. which can rotate together and which are driven by a friction drive, shown diagrammatically at 4| 4, until arrested by a stop pawl 4|5 engaging a notch in the element 4|3. For convenience in illustration, a separate friction drive is-sho'wn for the manifesting means in each denominational order, but it is obvious that a cornmon driving means which is capable of frictionally driving the manifesting means in the various denominational orders -could also be used.

Pawl 4| 5 is urged counter-clockwise (Fig. 2) about its pivot 4|6 by spring 4|1 into engaging relation with the notches in element 4|3 to arrest the scanning switch and the manifesting wheel 4|| in any one of the positions l to 9" and "0 as required by the digit value represented by tlie related denomination of the accumulator. A magnet 420 in the anode circuit of a control triode 42|, shown here as the lefthand triode of a twin triode, tube 422, of the aforementioned 2G51 type, will be energized to move the pawl 4|5 out of engagement with the element 4|3 and free the manifesting wheel 4|| and the scanning switch 4 |2 for movement whenever the control triode 42|-oonducts.

Control triode A42|, which controls the position of the pawl 4|5, has its anode `connected over thev winding of magnet 420 to the terminal 423, to which +300 volts is applied, andv has its cathode connected to ground over a vresistor 424 of 3,900 ohms.

Grid 425 of triode V42| is connected tothe read-out scanning switch 4|2 and has potential applied thereto as follows. The scanning switch 4|2, as it rotates, engages successively oneafter another of a series of contacts connected to digit-representing lines which are 'connected over resistors, as 426, of 2.2 megohms, to various ones of the anodes of the right and left triodes of the cascaded trigger pairs. Depending upon whether the trigger pairs are"on or of, the anode potentials of their left and right triodes will be either at +250 volts or at a lower potential resulting froml the drop across the anode resistors of conducting triodes. The pattern of the resistance network connectionsv for each denominational order is shown clearly in Fig. 2 and is so arranged that, for any digit represented by the combination of off and on" conditions of the cascaded trigger pairs, the line corresponding to that digit will have a potential which is less positive than that of any other line. By adjusting the cathode potential of the triode 42|, this least positive potential can be made to be the only one which will .be effective to bias the triode 42| to cut-off, thereby deenergizing the magnet 42-0 and allowing the pawl 4|5 to engagevin the notch in element 4|3. Ac'- cordingly, as the read-out scanning switch 4|2 is driven over its related contacts, itl will aping digit in reading. position, as indicated by the arrow 421, where they reman as long as cut- 2l ergize magnet 420, which moves the pawl 4|5 from engagement with the element 4|3 and frees the digit-'manifesting wheel 4|| and the scanning switch 4|2 for further movement until the scanning switch engages another contact which is at cut-off potential.

The potential of the cathode of control triode 42| is adjusted by a second triode 43B, which is the right triode of the twin triode, tube 422, connected f to resistor 424. The anode of this second triode 430 is connected directlyA to the '+300-voltterminal 423, and the cathode of the second triode 430 is connected to ground over the resistor 424.

Grid 43| of triode 430 derives its potential over an adjustable tap 432 from resistor l433, which is connected between the anode potential supply conductor 225, for the cascaded trigger pairsfand ground. By adjusting the tap 432. the potential on grid 43| can be made such that conduction in triode 430 will raise the potential of the cathode of triode 42| to a value which will be less positive than all but one of the potentials, the cut-oi potential, which are applied to' its grid 425 from the read-out scanning switch 4|2.

The second triode 430 has another very important function; namely, that of serving as a compensating means in the indicator control tube circuit to compensate for variations in potential applied to the anodes of the cascaded trigger pairs. Since the potentials sensed by the read-out scanning switch 4|2 and applied 'to the grid 425 are derived from the anode potential supply for the cascaded trigger pairs over conductor 225, variations in this potential would cause variation in the grid potential and possible misoperation of the digit-manifesting means. However, since the grid 43| of the second triode 430 is also supplied, through its tap 432 to resistor 433, with potential from the anode potential supply conductor 225, variations in the anode potential supply will cause a variation in the conductivity of the second triode 430, which will provide a compensating variation in the cathode potential of triode 42| to maintain the relation between the cathode and grid potentials of this triode substantially constant'despite variation in the potential supplied to the anodes of the cascaded trigger pairs.

The digit-manifesting means for the tens denominational order, as shown in Fig. 3, 'and for any other orders which might be provided in the accumulator, are controlled and operate in the same manner as described above.

The claims of the instant application are conned to the accumulator per se. Claims to the impulse generator are presented in a divisional application, Serial Number 215,483, and claims to the data-indicating means are presented in another divisional application, Serial Number 215,484.

While the form of the invention shown andl described herein is admirably adapted to fulfill the, objects primarily stated, it is to be understood that it is not intended to coniine the invention to the one form or embodiment disclosed herein, for it is susceptible of embodiment of various other forms.

What is claimed is:

. 1. In combination, four electronic devices, each operable alternately to on and to oil condition in response to impulses impressed thereon, and including means to produce potential changes each .time the device changes from either condition to the other, said devices by their on and off conditions, in combination, representing the digits l and 9 to ."0; circuits connecting the devices in series and enabling a potential change', produced by every operation of a device to said oi condition, to be transmitted as an impulse to the next device-of the series to cause an operation thereof; means to impress input impulses on the rst device of the series; a unidirectional circuit connecting the fourth electronic device in the series to the third electronic device in the series for transmitting a potential change, produced by the fourth electronic device as it is operated to on condition, as an impulse to the third electronic device to cause it to operate; and a second unidirectional circuit connecting the fourth electronic device of the series to the second electronic device of the series for transmitting'a potential change, produced by the fourth electronic device Aas it is operated to oi condition, as an impulse to the second electronic device to cause it to operate; said series connections and two unidirectional connections cooperating to enable the four electronic devices to operate to accumulate amounts in the decimalnotation by causing the electronic devices, in combinations, to progres# sively represent the digits l to "9 and 0 and to return to any particular digit-representing combination after ten impulses have been applied to the input means.

2. In combination, four pairs of electron discharge devices; circuits cross-connecting each pair of devices to form a trigger pair operable a1- ternately to on and to 01T condition in response to impulses and including means to produce potential changes each time the pair changes from either condition to the other, said trigger pairs, by combinations of on and off conditions, representing the digits l vto 9 and 0; circuits connecting said trigger pairs in cascade to transmit the potential change, produced by a trigger pair assuming its off condition, as an impulse to the next trigger pair of the cascade to cause it to operate and change its condition; means to preset the trigger pairsv with the rst, third, and fourth trigger pairs in said oil condition and said second trigger pair in said on condition; an input circuit upon which input impulses are applied to the iirstv trigger pair; a unidirectional feed-back circuit connecting" one of the devices of the fourth trigger pair to the third trigger pair to enable an impulse to be sent to the third trigger pair from the fourth trigger pair each time the fourth trigger pair operates to said on condition; and a further unidirec# tional feed-back circuit connecting the other of the devices of the fourth trigger pair to the second trigger pair to enable an impulse to be sent to the second trigger pair each time the fourth trigger pair operates to said off'condition.

3. In combination, four pairs of electron discharge devices, each of said devices containing at least an anode, a cathode, and means to con-l trol conduction therebetween; circuits for applying operating potentials to the devices and including an impedance in the circuit to each anode; trigger connections cross-connecting the anodes and the conduction control means of the devices of each pair to form them into a. trigger pair which will operate in on condition when current is conducted in one of the devices and in off condition when current is conducted in the other of the devices; circuits connecting the trigger pairs in cascade, the cascade circuits between .trigger pairs extending' from the anode of ateneo? said other device of a .pair to the conduction control means of both devices vof the next pair of the cascade, for transmitting the anode potential drop, as `the trigger pair turns to its off condition, to the next trigger pair to cause an operation thereof, the cascade circuits between'the first and-second trigger pairsand the second and third trigger pairs including an isolation impedance. in series with each of the conduction control means of the devices in the second .and third trigger pairs; means to apply input impulses to the conduction control means of the first trigger pair; alrst feed-back circuit vcontaining a unidirectional device and extending from a mid-point of the anode impedance of the other device of the fourth trigger pair directly toA the conduction control means of the other device of the second trigger pair of the cascade whereby to enable a portion of the impulse which is generated across the impedance to be applied directly to the conduction `control means of the other device of Y,the second pair to turn the second trigger pair to on condition each time the fourth pair goes from on" Yto off condition; a second feed-,back circuit containing a unidirectional device and extending from a mid-point of the anode impedance of the one device of the fourth trigger pair directly to the conduction control means of the other device of the -third trigger pair of the cascade whereby to enable a portion of the impulse which is vgenerated across that impedance to be applied directly to the .conduction control means of the other device of the third trigger pair to turn the third trigger pair to on condition each time the fourth trigger pair goes from off to on condition; said trigger connections, cascade connections, and feed-back .connections enabling the trigger pairs to count in the decimal notation and represent digits l to 9 and 0 by combinations of their on and o conditions.

4. In a device for counting in the decimal notation, the combination of four pairs of electron discharge devices, each of said devices containing at least an anode, a cathode, and means to control conduction therebetween; circuits for applying operating potentials to the devices and including an impedance element in the circuit to each anode; .trigger connections cross-connecting the anode-s and 4conduction control means of the devices of each pair -to form them into a trigger pair which will operate in on condition when current is conducted in one of the devices and in off condition when current is conducted in the other of the devices, the trigger pairs by combinations of on and off conditions representing the Vdigits and l to 9; circuits `connecting the trigger pairs in cascade, the cascade circuits between trigger pairs extending from the anode of said other device of a pair to the conduction control means of both devices of the next pair of vrthe cascade, for transmitting the full vanode potential drop, as the trigger pair -turns to its "ofP condition, to the next trigger pair to cause an operation thereof, the cascade circuits between the first and second trigger pairs and `second and third Vtrigger pairs including an isolation impedance element in series with each of the conduction control means of the devices in the second and `third trigger pairs: means to preset the first, third, and fourth pairs to on condition and the second pair to off condition; means to apply input impulses; tothe conduction control means of the first trigger pair; a first feed-back circuit extending from the mid-point of the anode 'impedance element of the other device of the fourth trigger pair directly to the conduction control means of the other device of the second trigger pair whereby to enable half of the impulse-.Which is generated across the anode impedance element of the other device of the fourth pair each time the fourth pair goes from on to:off condition to be applied directly to the conduction control meansof the other device ofthe second pair to turn the second pair to on condition, said feed-back circuit including a barrier-layer rectifier which is oriented to have a low impedance to negative feed-back impulses from the fourth trigger pair but a high impedance to negative impulses from the second pair; a second feedback circuit extending from the mid-point of the anode impedance element of the one device of the fourth trigger pair directly to the conduction control means of the other device of the third trigger pair, whereby to enable half of the impulse which is generated across the anode `impedance element of said one device of the vfourth trigger pair, each time the fourth pair goes from off to on condition, to be applied to the conduction control means of the other device ofthe third pair to turn the third pair to on c ondition, said second feed-back circuit including a lbarrier-layer rectifier which is oriented to have a low impedance to negative feed-back impulses from the fourth trigger pair but a high impedance to negative impulses from the third pair; the isolation impedance elements in the circuits to the conduction control means of the ,second and third pairs attenuating the effect of the feed-back impulses on the .conduction control means of said one tubes of these pairs and enabling half of the amount of ,impulses at the anodes of the fourth pair to .operate the second and third pairs, and the isolation impedance elements for the conduction control means Yof the other tubes of the second and third pairs and the portion of the anode impedance elements of the fourth ,pair Vbetween the anodes and the points to which the feed-back circuits are connected, cooperating with the rectiers to prevent impulses applied to the second and third pairs over .the cascade circuits from causing unwanted trigger operations in the fourth pair, thereby enabling small, compact barrier-layer rectiers having lower back impedance to be used in the feed-back circuits.

`5. In a device for counting in the decimal notation, the combination of four pairs of electron discharge tubes, each of said .tubes containing at least an anode, a cathode,.and means to control conduction therebetween; circuits for applying operating potentials to the tubes and including a resistor in the circuit to each anode; trigger connections cross-connecting the yanodes and control grids of the tubes of each pair to form them into a trigger pair which will operate in on condition when current is conducted -in one of the tubes and in 01T condition when current is conducted in the other of the tubes; circuits connecting the trigger pairs in cascade, the cascade circuits between trigger pairs extending fromthe anode of said other tube of a pair to the conduction control means of both tubes of the next pair of the cascade, for ltransmitting the full anode potential dropfas the trigger pair turns to its off condition, to the next trigger pair to cause an operation thereof, the cascade circuits between the viirs't and second trigger 4pairs and second and third trigger pairs including Jan isolation resistor lin series with each of the conduction control means of the tubes in the second and third trigger pairs; means to preset the first, third, and fourth pairs to on condition and the second pair to off condition; means to apply input impulses to the conduction control means of the first trigger pair; a first feed-back circuit extending from the mid-point of the anode resistor of the other tube of the fourth trigger pair directly to the conduction control means of the other tube of the second trigger pair whereby to enable half of the impulse which is generated across the anode resistor of the other tube of the fourth pair each time the fourth pair goes from on to oli condition to be applied directly to the conduction control means of the other tube of the second pair to turn the second pair to "on condition, said feed-back circuit including a crystal rectier which is oriented to have a low impedance to negative feed-back impulses from the fourth trigger pair but a high impedance to negative impulses from the second pair; a second feed-back circuit extending from the midpoint of the anode resistor of the one device of the fourth trigger pair directly to the conduction control means of the other device of the third trigger pair, whereby to enable half of the impulse which is generated across the anode resistor of said one device of the fourth trigger pair, each time the fourth pair goes from off to on condition, to be applied to the conduction A control means of the other device of the third pair to turn the third pair to on condition, said second feed-back circuit including a crystal rectifier which is oriented to have a low impedance to negative feed-back impulses from the fourth trigger pair but a high impedance to negative impulses from the third pair; the isolation resistors in the circuits to the conduction control means of the second and third pairs attenuating the eiect of the feed-back impulses on the conduction control means of said one tubes of these pairs and enabling half of the impulses at the anodes of the fourth pair to operate the second and third pairs, and the isolation resistor for the conduction control means of the other tubes of the second and third pairs and the portion of the anode resistor of the fourth pair between the anodes and the points to which the feedback circuits are connected being in series with the rectiiiers between the source of impulses applied over the trigger and cascade circuits to the conduction control means of the second and third pairs and the trigger circuits of the fourth pair and cooperating with the rectiers to prevent these impulses from causing unwanted 'trigger operations in the fourth pair, whereby small compact crystal rectiers having lower back impedance can be used in the feed-back circuits; and said trigger connections, cascade connections, and feed-back connections enabling the trigger pairs to count in the decimal notation and represent the digit notation 1 to 9 and 0 by combinations of their on and off conditions.

CARL F. RENCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Potter, pages 110-113, 358 and 360 of Electronics for June 1944.

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