Ncr Corporation

John J Rohulich

Daniel B Seevers

John Baird Keys

Apparatus and method for establishing and changing the volume level of a tone generator which may be used in connection with auditory feedback in a point of sale terminal or other business machine include a microprocessor having a timer with two settable registers which can be set to establish the duty cycle of a signal, an inverting buffer coupled to the timer output, an integrating circuit to which the signal from the buffer is applied, a transistor driver for a speaker to which the integrated signal is applied, and the speaker, the volume of the tone of which may be changed by altering the relative counts of the two timer registers.

Speaker volume control apparatus and method

A method and apparatus for establishing the volume level of a tone generator associated with a keyboard in which the tone generator will output a click tone when each key on the keyboard is actuated. In establishing the volume level of a click tone, the keyboard is put into a volume setting mode by the actuation of two key members of the keyboard. The subsequent actuation of each key member will produce a different volume level of the click tone. The actuating of a key member results in the storing of a count in a storage member. The storage member is then downcounted until it reaches zero. Upon reaching the count of zero, processing means generates a pulse train in which the pulse width is determined by the time it takes for the storage member to count down to zero.

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Cambridge, OH, United States of America

John J Rohulich