Patent GB-1273401-A (GB)
Title: Improvements in and relating to calculating machines
IPC: G06C15/08
Filed: 1969-08-12
Abstract: 1,273,401. Calculating machines. COMMODORE INTERNATIONAL Ltd. 12 Aug., 1969 [20 Aug., 1968], No. 40260/69. Heading G4B. The Specification relates to calculating machines of the ten key keyboard and transversely movable pin carriage type and capable of performing the operations of addition, subtraction, multiplication and division. When executing division, the dividend is set up in the pin carriage and then transferred to an accumulator from which repeated subtractions of the divisor are made to give the quotient. The dividend is entered into the accumulator with its highest order digit stored in the highest order pinions of the accumulator and its lowest order digit followed by a series of zeroes so that the quotient can be calculated to a desired degree of accuracy. In order to print the dividend with its lowest order digit in the lowest order digit printing position (i.e. not followed by this series of zeroes), the invention provides means whereby on entry of the dividend and depression of the division key, the dividend is sensed in the pin carriage and printed before the pin carriage is shifted and zeroes set in all its unused orders ready for transfer to the accumulator. In the embodiment shown, the dividend is entered into the pin carriage 8 in tne normal way. Depression of the division key 275, Fig. 24, pushes lever 125 which acts through linkage, not shown, to set means for preventing entry of the dividend into the accumulator A, Fig. 1, during the first rotation of the machine main shaft 59. Depression of key 275 also acts through linkage 280, 279 and 278a to move a plate 282 to the right towards the position shown, where its surface 282b is located above but prevented from contacting boss 283a by surface 282c abutting pin 287 carried by a cam follower 286. Depression of key 275 also energizes the machine motor. During the first clockwise rotation of the main shaft 59, cam 283 causes clockwise rotation of follower 286 which allows plate 282 to fall to the position shown, in which end surface 282d is aligned with pin 287. During the first 180 degrees of rotation of shaft 59 racks 16 and type bars 38, Fig. 1, are moved upwardly until they engage the pins set in carriage 8. A further type bar (not shown) is also raised until a division sign it carries is aligned for printing. Printing of the dividend and the division sign is made. During the second 180 degrees of rotation of shaft 59 the racks and type bars are lowered, the means effecting entry into totalizer A is shifted to permit such entry during the next rotation, and cam follower 286 is rotated clockwise causing pin 287 acting through end surface 282d to shift plate 282 to the right. Plate 282 is pinned to a lever 278a, 278e which thus rotates anticlockwise about 128 causing the arm 278e to move a zero setting plate 208 to the right and set zero pins in the remaining orders of the carriage. This setting causes movement of the carriage, because of the normal escape mechanism, until its highest order is beneath the highest order totalizer pinion. Movement of plate 208 to the right also acts through link 207 to position a printing hammer stop to prevent printing during the next rotation. The second rotation of the main shaft thus causes entry of the dividend into the totalizer in the required position. The shifting of plate 282 to the right during the second half of the first rotation also acts through linkage 282e, 353 and 137 to set a mechanism, Figs. 12 and 13 (not shown), which in turn acts to reset a totalizer 152 to zero when the racks 16 are raised for the second time. The divisor is subsequently set up in the pin carriage and repeatedly subtracted from the number in accumulator A, the quotient being stored in accumulator 152. The Specification also describes the basically conventional ways in which the machine may be operated for addition, subtraction and multiplication, the last-mentioned being performed by a repeated addition process.