Abstract: A process for determining the center of data disk tracks. The transducer head is positioned to one side of a track. The head repeatedly reads the track and microsteps across the track. The number of microsteps taken at the position on each side of the center of the track where a certain number of error correction code errors occur, are designated as boundaries of that track. The center of the track is then calculated as being half-way between the boundaries. By using the microstep off-sets for the centers of two tracks on a data disk, a correction factor can be calculated to compensate for thermal expansion of the data disk.

Abstract: 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.

Abstract: 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.

Abstract: 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.