Data input for electronic calculator or digital processor chip

Abstract

An MOS/LSI semiconductor chip for providing the functions of an electronic calculator or digital processor includes a RAM for data storage, a ROM for program instruction storage, an arithmetic unit for performing operations on data, and control circuitry for defining the functions of the machine in response to instructions from the ROM as well as conditions in the machine and inputs from external. The operation is digit oriented in that in a machine cycle one digit of the RAM is accessed, and also the ROM is addressed to provide an instruction word which is decoded and executed. The data input to the system is by four parallel lines which may be connected to a scanned keyswitch matrix or to BCD or binary data sources. Within the chip, the data inputs may be coupled to the input of the arithmetic unit, or to the data memory directly.