MOS electronic calculators



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In the last few years, the progress made in Matal-Oxide-Semi-conductor Large-Scale-Integration, MOS/LSI, has made possible the implementation of logic circuit complexities on a few integrated circuits never before dreamed possible. The purpose of this report is to further these developments by designing a Four-Function Calculator that can be implemented on three MOS/LSI circuits. First, specifications of a calculator are established, then the various components of the calculator are designed. The master oscillator, keyboard, output device, and power supply are the only sections not to be designed on the three MOS/LSI chips. The design is further narrowed to the three circuits. The first circuit (TIMING GENERATION) contains all of the counters that generate signals for bit, digit, decimal point, and output timing requirements. The second circuit (DATA MANIPULATION) contains the circuits required for keyboard encoding, the adder-subtractor, buffer register and accumulator. The third circuit (PROGRAMMABLE LOGIC ARRAY) contains the flip-flops and logic gates required to perform the function of controlling the various calculator operations. Detailed flow charts are derived for every function performed by the calculator; and together with basic MOS logic blocks, the entire calculator logic and circuit designs are achieved.