Abstract: A keyboard entry circuitry for calculator purposes is of the key strobing type wherein one each end of respective key of a keyboard is operatively coupled with corresponding digit time signal or key strobing signal while the other ends of the respective keys are connected in common with each other, whereby the identity of a specific actuated key is provided by determining which one of the key strobing signals is developed via that actuated key. Two kinds of digit time signals are placed within a one-word time sequence, one having different timing phases for the respective keys for key strobing purposes set foth above and the other having the same timing phase for all the keys for shortening a period of time required for key determinations. Once there is a equivalency with respect to both the key strobing digit time signals and the common digit time signal, the indication of any actuated key is provided.

Abstract: A display energizing circuit associated with calculators for displaying on a time sharing basis numerical or alphanumerical symbols on a multi-digit gas discharge panel. Means are provided for preventing segment signals from being applied to segment electrodes or cathode electrodes of the gas discharge panel at one or more dead digit times which are provided within a one-word time period for other purposes. This avoids damage to circuit elements in the display energizing circuit, for example, switching transistor elements associated with counter electrodes or anode electrodes of the display panel.

Abstract: A large scale integrated circuit central processing unit for calculator applications generally includes at least one information storage register and means for generating a word time signal designating the effective digit capacity of the information storage register. An additional external terminal is provided for the package of the integrated circuit to accept control signals applied thereto which are effective to modify the pulse width of the word time signal. Application of the control signals to the external terminal renders the word time signal generating means operative to enable the modification in the pulse width of the word time signal and hence in the effective digit capacity of the storage register.