497,640. Calculating - machines. NATIONAL CASH REGISTER CO. March 22, 1937, No. 8413. Convention date, Jan. 6. [Class 106 (i)] A calculating-machine is provided with selectively operable means adapted, during a single continuous operation comprising a plurality of cycles and immediately following an item-entering operation in which an overdraft is left in a balance totalizer in complementary form, either to convert the complementary overdraft to true negative form, print it and reset the totalizer to zero, or to convert the said overdraft into true negative form, print it and then re-enter it in complementary form into the totalizer. General operation. The invention is described as applied to an Ellis machine of the type shown in Specification 420,807 and having three adding and one adding and subtracting or " balance " totalizer. In the system of accounting referred to in the present Specification, an overdraft in the machine is regarded as a credit balance. Two overdraft keys are provided, designated in the Specification as " credit balance " and " subcredit balance " keys, but hereinafter referred to as " overdraft total and " overdraft subtotal " keys respectively. The depression of the overdraft total key initiates four continuous machine cycles. During the first cycle, the overdraft, which is standing in complementary form in the balance totalizer, is cleared therefrom and added into a storer. During the second cycle the complementary overdraft is cleared from the storer and subtracted from the balance totalizer, this totalizer then containing the true negative overdraft. During the third cycle, the true negative overdraft is cleared from the balance totalizer and added into the storer, and in the fourth cycle the true negative overdraft is cleared from the storer and is printed. The depression of the overdraft subtotal key also initiates four cycles, the first three of which are similar to those described above. In the fourth cycle, however, the true negative overdraft is cleared from the storer, printed and subtracted from the balance totalizer so that this latter then again contains the original complementary overdraft. The printing mechanism is disabled during the first three cycles. Overdraft totals and subtotals are printed in the same distinctive colour. Starting machine by starting bar. Depression of the starting bar 75, Fig. 4, rocks anti-clockwise a lever 80 to rock clockwise a lever 82 having fingers 83, 84, Fig. 5, which engage a projection 85 on a slide 86 on a lever 72 whereby this lever is also rocked clockwise to move a pin 71, Fig. 4, thereon away from a lever 69. A spring 74 then rocks anticlockwise a lever 65 connected by a link 67 to the lever 69, an arm 63 being lifted to allow the engagement of a clutch 60. The lever 65 also closes a motor-switch. A crank 88 is accordingly rotated and rocks a crank 90 secured to the main shaft 91. During the rotation of the crank 88, a cam surface 92 thereon engages an arm 93 of the lever 65 to restore this lever and so stop the operation after one rotation of the crank. A part 94 of the lever 69 engages a pin 95 on the slide 86 and lifts this slide to bring its projection 85 inside the fingers 83, 84 so that the lever 72 is restored by a spring to move the pin 71 to lock the lever 69 and thus prevent a further cycle of operation even though the starting bar 75 has been held depressed. Starting machine by skip bar. The depression of the skip bar 97, Fig. 4, causes the carriage to be tabulated to a predetermined columnar position as described in Specification 461,423. A projection 96 attached to the starting bar 75 causes the simultaneous depression of the latter bar and starts the machine as described above. Starting machine by " line feed " bar. Depression of a bar 98, Fig. 4, controls line feeding in a known manner. The stem of the bar is slotted to engage a pin 99 on the lever 82 and this lever is thus operated to start the machine as described above. Releasing depressed . amount keys. The depression of a release key 1021, Fig. 20 by means of a link 289 moves to the left a slide 291 which rocks an arm 293, connected to an arm 295 having a pin 296 which acts on sloping projections 297, 298 to move a detent plate 116 to the right to release any depressed amount keys, the projections also moving a zero-latch release plate 119 to the left. The amount keys are also released automatically, a pawl 300 being pivoted on the slide 291 and during the initial clockwise movement of the main shaft 91 being urged anticlockwise by a spring so that, during the anticlockwise return movement of the main shaft a roller 302 on a disc secured to .the shaft engages the pawl 300 and pulls the slide 291 to the left to release the depressed amount keys. When a total key or when the overdraft total or overdraft subtotal key is depressed, a lever (not shown in Fig. 20) engages a pin 323 on a lever 307 pivoted to a pawl 305 and rocks the lever anticlockwise to remove a pin 308 away from a lever 309 pivoted to the slide 291. The lever 309 is then rocked by a spring into engagement with a roller 317 on an arm 318 which is rocked by the main shaft 91 whereby the slide 291 is moved to the left to release any depressed amount keys and, by means of the plate 119, to release latches from the differential actuators immediately at the beginning of a total-taking operation. Repeating mechanism. The amount-key releasing mechanism is disabled when the add key 1022, Fig. 20, for No. 2 totalizer is depressed. This depression allows the rocking of the latch 305 so that the lever 307 is moved to the left to bring a pin 329 beneath the pawl 300 and so, hold this pawl out of action. Supersession of repeat and add function by depression of total and overdraft total and subtotal keys. If the lever 307 is moved to the left by depression of the No. 2 add key and a total or overdraft total or subtotal key is then depressed, the lever 307 is rocked anticlockwise as described above and its end 328 comes into the path of the roller 302 so that initial clockwise movement of the main shaft moves the lever 307 to the right to rock the latch 305 to release the depressed add key 1022. Distinguishing marks and colours. Ink-ribbon mechanism. The ink ribbon 57, Fig. 11, has a black part and a red part as shown. The black part is raised to operative position in adding operations by a fork 235, a lever 238, a link 241 and a lever 242 pivoted at 243 and rocked clockwise by a link 245 pivoted to an arm 246 on the clockwise-moving printer shaft 133. The movement of the lever 242 is arrested by the engagement of a pin 247 thereon with a hook 248, continued movement of the link 245 being permitted by a pin-and-slot 244. In subtraction, the hook 248 is rocked clear of the pin 247 and the lever 242 is moved a greater distance by the link 245 to lift the ribbon 57 higher to bring the red part to printing position. The hook 248 is operated by a pin 265 on an arm 259 connected to a yoke to which is pivoted a link which, when the subtract key is depressed, is latched over a stud carried by the balance totalizer engaging link. Subsequent movement of this link then rocks the yoke to operate the hook 248. A further arm on the yoke engages a pin 268, Fig. 12, on a bar 269 and moves this bar to the right to bring a pawl 271 into the dotted position. When the printer shaft 133 is returning anticlockwise, an arm 246 thereon rocks anticlockwise a lever 275 which then engages the pawl 271 and restores the bar 269, the yoke and the associated parts, including the hook 248. Since the balance totalizer is engaged subtractively during overdraft total or subtotal taking operations, overdraft totals and subtotals are printed in red. Moreover, mechanism operated by a cam which controls the engagement of the storer positions a type sector to cause the printing of a special symbol against overdraft totals and subtotals. Starting machine by overdraft total and subtotal keys. The overdraft subtotal key 331, Fig. 4, has slots engaged by pin 336, 337 secured to the overdraft total key 332. The depression of the overdraft subtotal key 331 thus carries the overdraft totals key 332 down at the same time, whereas depression of the overdraft total key has no effect on the overdraft subtotal key. Depression of either key lowers a plate carrying a pin 345 which rocks a latch 357 to release a lever 359 which is then rocked clockwise by a spring to engage a roller 366. Fig. 24, with a control cam 367. The lever 359, Fig. 4, is connected by a link 368 to the lever 80 which starts the machine as described above. The lever 359 also releases a latch 370 to hold the pin 71 clear of the lever 69 so that the machine is not stopped after one cycle. Towards the end of the third continuous cycle, the control cam 367 restores the lever 359. The latch 370 is consequently moved away from the pin 71, and the machine stops at the end of the fourth cycle. To prevent starting until one or other key has been fully depressed the lever 359, Fig. 24, is connected by a link 374 to a link 409 pivoted to the clutch control lever 65 whereby the link 409 is brought beneath a pin 415 on an arm 416 connected to a detent 396 which is rocked to allow the link 409 to rise only when the key is fully depressed. Disabling printing mechanism. The printing mechanism is disabled during the first three cycles of an overdraft total or subtotal-taking operation. The lever 359, Fig. 24, rocked clockwise upon depression of the overdraft total or subtotal key moves to the right a link 374, which unlatches a printer-operating link 111 from a stud 110 on a crank arm on the main shaft 91. The lever 359 is restored at the end of the third cycle by a control cam 367 and a spring 377 acting on the link 374 relatches the printer operating link 111 to the stud 110 so that printing occurs during the fourth cycle. Control cams. Depression of either the