735,750. Digital electric calculating apparatus; statistical apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 26, 1953 [Aug. 29, 1952], No. 23550/53. Class 106 (1). In record-controlled accounting machines all values are entered additively, and means are provided for ascertaining the sign of each amount prior to its entry and causing inversion of the amount in the accumulator prior to and after the entry of each amount having a selected sign such as negative or positive. The accumulator comprises a series of multicathode counting tubes of the type described in Specification 734,903. Negative pulses applied to the transfer cathode group T0-T9 of each of these tubes cause the discharge glow to advance step by step on cathodes D1 to D9, while a negative pulse applied to the cathode groups C0-C9 of all the tubes causes the discharge in each tube to move to the cathode D1-D9 representing the nines complement of the previously registered digit. Data'is read from record cards in the form of differentially timed pulses obtained through electrical sensing brushes in the usual way. Two sets of brushes read successive cards simultaneously. The first set includes brushes to detect perforations indicating whether the number on-the card is positive or negative ; it also includes a brush to detect a perforation for initiating a total taking operation. The detection of a positive or " add " perforation causes a rise in potential on the line 45, Fig. 4, which triggers a thyratron T35. This causes energization of a magnet A which closes contacts a to connect the cathode of another thyratron T47. to a line 42 communicating with the trigger electrodes of a series of thyratrons T43 ... T46. The thyratron T47 is controlled by cam-operated circuit breakers CB1 ... CB5 to provide ten pulses on the line 42 during the card-reading period. When a digit perforation is sensed by one of the second set of brushes a positive pulse is transmitted over one of the lines 55, Fig. 1, to the trigger electrode of one of the thyratrons T19 ... T22 according to the order of the digit The firing of this tube causes a rise in potential. at its cathode which is communicated to the upper control electrode of the related tube T43 ... T46. This latter tube is now in condition to pass the succeeding pulses produced by the electronic circuit breaker T47 via a line 29 to the transfer cathode group T0-T9 of the associated counting tube G. Negative entries. The detection of a " subtract " perforation triggers a tube T36, Fig. 4, and causes energization of a relay S which again connects the electronic circuit breaker to line 42 through its a contacts, Relay S also shifts d contacts, Fig. 3, to cause triggering of a tube T23 which supplies a negative pulse on line 21 to the complementing cathodes C0-C9 of all the counting tubes G thus changing the amount in the accumulator to its nines complement before the number is sensed and added into the accumulator. The reinversion of the amount in the accumulator is carried out automatically but is delayed until the sign of the number in the next card has been determined; if it is negative also, reinversion is suppressed. Tens carry. When the discharge in any of the counting tubes G leaves the D9 cathode a negative pulse is applied to the primary winding 71 of a transformer, causing a positive pulse in the secondary winding 72 which renders the related tube T31 ... T34 conductive. The rise in voltage at the cathode of this tube is communicated to the upper control grid of the tube T43 ... T46 associated with the next higher order. This rise is not sufficient to allow the normal digit pulses to pass, but at the " 0 " time in the machine cycle contacts CB11, Fig. 4, open and change the voltage on line 50 from - 100 to - 50; this change of bias allows any of the tubes T43 ... T46 which have been primed by a carry from a lower order to respond to the tenth pulse from the tube T47 and step on the associated counting tube G. The duration of this pulse is sufficiently long to allow carry-through-carries to be completed. Provision is made for entering " fugitive one." Total taking is initiated when a particular perforation sensed in a special card causes a tube T12 to conduct and energize a magnet R0. This provides for the ten pulses from the electronic circuit breaker to step on all the counter tubes of the accumulator together. The tens carry controls are suppressed and contacts g, Fig. 2, in the cathode circuits of tubes T31 ... T34 are transferred so that magnets 86 are energized as the associated counting tubes pass from " 9 " to " 0." The magnets control wellknown printing or other recording devices. A means is provided to automatically detect the presence of a " 9 " in the highest order (indicating a complement) and invert the amount before reading out. The machine can be arranged to count the number of holes sensed instead of summing the values represented by them. A means is provided for checking that the accumulator has been properly cleared after a zeroizing operation.