Kabushiki Kaisha Toshiba

Tosbac Computer System Company Limited

Tetsuaki Iwasaki

Hiroshi Ushiki

Akira Masuda

A calculation method suitable for use in statistics calculations and a calculator using the method are disclosed. The method has the steps of storing a memory content from a memory in a first register of a calculation circuit; storing input data in a second register of the calculation circuit; performing a calculation on the contents of the first register and the second register, and storing the result of the calculation in the first register; determining that the calculation result stored in the first register has not overflowed; transferring the content of said first register to the memory and overwriting the memory content therewith, if the calculation result has not overflowed after the processes have been repeated a specified number of times. The calculator has an input section for inputting data; a calculation section for performing a specified calculation on the data; an overflow determination section for determining whether or not a calculation result that is the result of the calculation has overflowed; a calculation totalling section for determining whether or not the calculation has been performed a specified number of times; and a memory section for storing the calculation result obtained by the calculation means, if the calculation totalling means has determined that the calculation has been performed the specified number of times.

Overflow detection calculator and method of overflow determination

In an integrated circuit for arithmetic operation and display control connected to a power source (46) and a liquid crystal display device (45), and energized by the power source, including an arithmetic operation circuit (42) for performing a designated artithmetic operation, wherein the result of the arithmetic operation is displayed by the display device, a boosting circuit (43) receives and boosts the voltage from the power source (46), a drive circuit (44) is powered by the boosting circuit (43) to drive the liquid crystal display device (45), and a control circuit (41) causes interruption of the driving of the display device when the arithmetic operation circuit (42) is carrying out the arithmetic operation.

Display control circuit

A plurality of key switches are provided between each pair of external terminals. A logic circuit generates time-division signals sequentially. The logic circuits stops the generation of these time-division signals during a blanking period with a predetermined time duration, thereby to stop the through-current during this period. The plurality of time-division signals are input to a plurality of buffer circuits. The outputs of the buffer circuits are supplied to the external output. Detection circuits detect only the operated key switches on the basis of the time-division signals and the signals from the external terminals exclusively used for key signal inputting. A plurality of switch members are provided between each of the external terminals and the reference potential. These switch members are conductive during the blanking period to improve the drive capability for external load.

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Tokyo, Japan

Tetsuaki Iwasaki