Expandable function electronic calculator

Abstract

An electronic portable calculator implemented in MOS/LSI technology and including a scanned keyboard input and display output. The calculator system utilizes a plurality of output terinals on the primary MOS/LSI chip for selectively addressing in timed coded sequence an array of peripheral MOS/LSI chips providing for expanded register and memory capacity and for output printing. Data registers are provided in a sequentially addressed random access memory array, which is addressed by a commutator also used to generate encoded timing signals for other parts of the system and control logic. The keyboard input includes an interface register into which is entered key sense line information along with encoded timing information derived from the encoded timing signals. The contents of the interface register may be entered into the data registers or used to select an address in a program storage memory via a program counter. Bits may be read out in parallel from cells in the data registers and processed through an arithmetic logic unit and then re-entered in the same cells within a bit time or state time, so the data registers do not recirculate in the usual sense.