Hewlett-Packard Company

David S Cochran

France Rode

Allen Jay Baum

Thomas E Osborne

Peter D Dickinson

Alexander D Walker

William L Crowley, Jr

Chung C Tung

The battery powered hand-held calculator for performing the arithmetic, trigonometric and logarithmic functions disclosed herein includes a factorial function which conveniently calculates factorials of positive integers.

General purpose calculator having factorial capability

This specification describes a power control circuit for reducing the brightness of multi-segment light-emitting diode (LED) characters in proportion to the number of segments illuminated to compensate for the apparent greater brightness of those characters having more segments illuminated than others. Since brightness is a function of power, the power required to drive multi-segment characters is substantially reduced, which extends useful battery life of battery powered equipment having light-emitting displays. Since less power is required by the display, the power driving and dissipation capability of the drive circuitry is also reduced.

Automatic display segment intensity control

A battery-powered, hand-held, calculator employs MOS/LSI calculator circuits to perform arithmetic and financial calculations. Data and commands are input to the calculator from a keyboard having shift key to double the functions of selected keys. A 15-digit, seven-segment light emitting diode (LED) display serves as the output for the calculator. The calculator circuits include a read-only memory circuit in which the algorithms for performing the arithmetic and financial calculations are stored; a control and timing circuit for scanning the keyboard, retaining status information about the condition of the calculator or of an algorithm, and generating the next read-only memory address; and an arithmetic and register circuit containing an adder, a group of working registers, a group of data storage registers forming a stack for roll down operation, and a constant storage register. These circuits are interconnected by a multiple line buss system.

General purpose calculator with capability for performing

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Palo Alto, CA, United States of America

David S Cochran