Electronic calculator or digital processor chip with multiple code

Abstract

An MOS/LSI semiconductor chip for providing the functions of an electronic calculator or digital processor includes a data storage RAM, 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. Input and output terminals are provided, as for keyboard input and display output. The operation is digit oriented in that an instruction accesses one digit of the RAM. One set of output terminals may be used for sequentially scanning the display digits and keyboard matrix; several of these may be actuated in any order or code combination, so the same terminals may be used to address an auxiliary RAM or drive a printer. Another set of output terminals may provide the segment outputs to the display. The two sets of output terminals are separately controllable. The data to both sets of output terminals is latched, so the machine can execute other instructions while a given output subsists.