GB1042789A - Improvements in or relating to calculating machines - Google Patents

Abstract

1,042,789. Digital-electric calculating apparatus. BELL PUNCH CO. Ltd. March 16, 1965 [March 21, 1964], No. 10979/65. Divided out of 1,042,785. Heading G4A. An electronic calculating apparatus includes a decimal register with means L (Fig. 3, not shown), for indicating the position of the decimal point of a number stored in the register, the position being controlled by a ring counter D.C. wherein stepping pulses applied to the counter D.C. pass through a plurality of gates D.G. controlled by a bi-stable device B.D. The methods of setting numbers in the register with their decimal points, and of performing division is as described in Specification 1,042,787. Multiplication.-In a first method in which a multiplicand in the register is multiplied by successive digits set on a bank of multiplier keys (see Specification 1,042,786), when the position corresponding to the depressed decimal point key D.K. is reached, a transistor T.R. is rendered conductive, setting the bi-stable device B.D. to pass pulses through a gate D.G.2 to step the counter to the position corresponding to the switch D.K. Entering of subsequent digits permit passage of one pulse through a gate D.G.3 and eleven pulses through the gate D.G.2 until the multiplier decimal point key is depressed placing a negative potential on a terminal D.P. to prevent the gate D.G.3 conducting and thus preventing further stepping of the decimal point. In a second method in which a multiplicand on the keyboard is multiplied by a multiplier in the register (see Specification 1,042,786), the bi-stable device B.D. is initially set through a gate D.G.13 and eleven pulses are added to the counter D.C. through a gate D.G.4 during each cycle until in the last multiplication stage the bi-stable device B.D. is unset through a gate D.G.9 and then set again through a gate D.G.7 at a time determined by the actuated keyboard decimal key D.K., thus stepping the counter decimal point a number of times determined by the multiplicand.