537,502. Calculating-apparatus. NATIONAL CASH REGISTER CO. Oct. 19, 1939, No. 28214. Convention date, Dec. 30, 1938. [Class 106 (i)] In a machine particularly adapted for keeping accounts means are provided whereby in one and the same machine operation, a record may be made of a true negative total or sub-total from an add and subtract totalizer as well as a total or sub-total from an add totalizer. The means described ensures that when a positive or negative balance total or sub-total is printed a record is also made of the number of items such as cheques, bills, invoices &c. involved in the transactions. The invention is described as applied to an Ellis machine as set forth in Specifications 28253/08, [Class 106], 497,640, and 506,500. The machine shown comprises a main operating mechanism, a keyboard with amount, item and control key banks, a differential rack mechanism, an add-substract or balance totalizer, a number of adding totalizers, a paper carriage with control devices and a printing mechanism. The main operating shaft 25, Fig. 1, is given one complete oscillation for single cycle operations such as addition, subtraction and total taking and is given four complete oscillations for four cycle operations in taking true negative totals or sub-totals. The amount key banks co-operate with the usual differential racks and are aligned with a balance totalizer I and adding totalizers II, III, IV and VI selectively controlled by keys or by means associated with the paper carriage. Item counting mechanism. -Three banks of item keys 33 co-operate with differential racks 34 aligned with an item totalizer V. The units bank is normallv conditioned to move automatically one unit for single items but the keys can be depressed to enter the number of items in a batch of cheques &c. A key or carriage control is provided to prevent automatic movement when necessary. The mechanism for this purpose is similar to that described in Specification 506,500 and comprises sliding plates that co-operate with zero stop pawls 36 .. 39, Fig. 12. The pawl 36 for the units bank is formed with two steps one of which holds the rack in home position and the other permits one step of movement. The pawl 36 is also associated with a second pawl 40 to ensure that the one step of movement will not be made in the event of a number ending in a cypher being entered in the key banks. The pawl 36 is raised by means of a rod 49 lifted by the zero stop pawl 39 associated with any one of the amount differential racks. An entry of a number in the units bank moves the pawl 36 through a greater distance than the rod 49 and raises the pawl 40 to free the rack entirely. Depression of the keys in the higher banks operates the pawls 37, 38, to rock a shaft 54 and depress a slotted link 71 to hold the pawl 40 in effective position to lock the units rack in home position if no key in the units bank is depressed. Carriage control of item totalizer racks.-A pivoted latching member 79, Figs. 1, 2 and 7, which engages shoulders on the racks, is controlled by a link 80 carrying a stud 69 in engagement with a cam lever 84 on the main shaft and formed with a lug 85 in contact with an arm 86 of a bell crank that is operatively connected to a link 100. In certain positions of the carriage control elements 101 rock a lever 89 to raise the link 100 and thereby the arm 86 to free the link 80 so that when the main shaft is operated the latching member is rocked to free the racks for movement. Key control of item totalizer racks.-The stems of the control keys co-operate with a sliding plate 110 connected by a link 109 to an arm on a shaft 87 which carries an arm 107 formed with a surface 115 and having a pin 106 to co-operate with the bell crank 86. In the extreme positions of the plate 110 the surface 115 is out of the path of movement of the lug on the link 80 but in intermediate positions it is moved in front of the lug to block the link 80. The movement of the plate 110 is utilized to set the symbol printing segment in the known manner. A " no count" key, Fig. 8, cooperates with an auxiliary slide 119 engaging a pin extending from the sliding plate 110 to move it, when the key is depressed, to an intermediate position to block the link. A key 124, Fig. 7, may be depressed to overcome the automatic carriage control of the plate 110. Item totalizer engaging means.-The main shaft carries an operating plate 125, Figs. 3 and 4, with the usual flying lever 126, bell crank 128 and engaging link 127. In the present embodiment cheques only are to be counted and means are provided to prevent engagement of the item totalizer V except during cheque entry operations. For this purpose a spring-controlled bell crank 151, which is normally held by a retaining pawl 149, is provided with a pin 154 to act on the bell crank 128 and turn it so as to move its end out of the path of movement of a stud 145 on the operating plate 125 and thus prevent engaging movement. In the cheque entry column a carriage control element raises a link 148, Fig. 4, to rock the retaining pawl 149 and release the bell crank 151 to prevent action of the bell crank 128. Total and sub-total operations.-In these operations the item totalizer V is engaged at the beginning of a cycle by the usual engaging mechanism comprising interconnected levers 161, 162. The levers, in the present embodiment, are secured to the hub of a rotatable and slidable collar 166 and are resiliently connected to a lever 164 on the collar. The lever 164 has a pin connection with a yoke 181, Figs. 4 and 6, of a total control lever 189 which is conditioned on depression of the balance key for totalizer I so that the number of items will be printed with the balance. The collar 166 is shiftable axially to render the levers 161, 162 ineffective to control the item totalizer engagement. Overdraft or negative total and sub-total operations.-When the balance totalizer is in overdrawn condition the balance key is locked so that the total or sub-total overdraft keys must be depressed to condition the four-cycle mechanism for operation. During the four complete oscillations of the main shaft 25 a cam assembly 198, Fig. 2, makes one revolution. In addition to controlling the engagement of the totalizers I and V this mechanism controls associated storage devices comprising pinions 191 on rockable frames which co-operate with racks 196 on the differential actuators. The sequence of operations in taking an overdraft total or sub-total is described in Specification 497,640. In accordance with the present invention the action of the item totalizer V during these operations is controlled in the following manner. The totalizer V is zeroized during the first cycle and the item entered into the associated storage pinions and left thereon until the end of the third cycle. In the fourth cycle, in total operations the storage pinions for the item totalizer V as well as those for the balance totalizer I are reset and the amounts transmitted to the racks and printed. In sub-total operations the totalizer I must be engaged during the first half of the fourth cycle and the totalizer V during the second half. For this purpose independent control of these totalizers is permitted by shifting the collar 166 axially through the action of a cam 199, linkage 200, 214, 242, and cam lever 243. The complement of the negative total is thus replaced on the totalizer I by the means shown in Fig. 16. This mechanism is described in Specification 497,640 and is modified to control the engagement of the totalizer I in the last half of the fourth cycle. The cam 261 rocks a shaft 248 on which is mounted a finger 249 that is adapted to rock a bell crank 251, Fig. 4. The bell crank is operatively connected to an arm 259 which in its displaced position is effective to contact the flying lever 126 and cause engagement of the totalizer V in the last half-cycle. Operation counter.-Operations involving the balance totalizer I are registered on a counter 300, Figs. 2 and 13, to provide a record of the number of deposit and withdrawal transactions. The counter is actuated by a pawl 309 on a link 307 operatively connected to the balance totalizer engaging link 301. The link 307 is normally held in inoperative position but is lowered, by a link 311, to effective position, when an amount key is depressed, by a linkage connected to the key operated shaft 41. Actuation of the counter is prevented during total and sub-total taking operations by the co-operation of an arm 321 with the arm 323 of a yoke 325 rocked counter-clockwise when the total or sub-total key is depressed to hold the link 311 in raised position.