Abstract: A push button switch provided with a multistage actuation interlock function is composed of a casing; a pair of push buttons arranged side by side passing through an upper lid of the casing; a plurality of movable bodies arranged movably in a direction perpendicular to a depression direction of the push buttons into the casing; a plurality of movable contacts attached to the movable bodies, respectively; and a plurality of fixed contacts arranged on a base portion of the casing in confronting positional relationship with respect to the movable contacts. When each of the push buttons is depressed at each of the multistage stroke, the movable body is shifted to bring the movable contact into contact with the fixed contact, respectively in sequence. Further, an interlock plate is interposed between and associated with the two push buttons in the casing.

Abstract: During expansion of differential pulse code modulation PCM data into (PCM) data, particularly for speech data in data processing, the range of oscillation of the PCM data can be centered about an amplitude level when each current PCM value has a small value .DELTA. subtracted from it or added to it when respectively positive or negative to obtain a corrected current PCM sample value. Even if manipulation involved in data editing, such as division or connection, of differential or expanded PCM data has been performed or if an error has occurred during transmission of differential PCM data to produce an offset, such offset can be quickly corrected during the expansion.