KEYBOARD ENTRY CIRCUITRY OF THE KEY STROBING TYPE

摘要

Keyboard entry circuitry for an electronic calculator is of the key strobing type wherein one end of individual ones of a plurality of keys in a keyboard are operatively coupled with corresponding digital time signals or key strobing signals while the other ends of the keys are connected in common with each other. In this way 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 digital time signals are placed within a one-word time sequence, one having different timing phases for the respective keys for key strobing purposes set forth 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 equivalency with respect to both the key strobing digital time signals and the common digital time signal, identification of any actuated key is provided.