| Nowadays, all functions of a calculator including calculating units, display driver, keyboard interface and so on, are integrated on one single chip. As key technology of the single chip calculator, the highly integrated dynamic CMOS logic implement and the micro program design are now owned only by the developed countries and kept in secret. Based on the conjunction of "top-down" and "bottom-up" design approach, the hardware system and micro program design of the calculator is thoroughly studied in this paper, and finally has been mastered. A typical calculator chip from RCL semiconductor Inc, C9821,is referenced and developed .The chip of the calculator consists of several function units such as RC oscillator, power management module, Microprogrammed Control Unit(MCU), register group, LCD driver and keyboard interface. Each unit is extracted from the circuit, and is analyzed detailedly in framework, configuration and design approach.The instruction system of C9821 is unscrambled and then the instruction decode algorithm are obtained. The complete program of C9821 including basic arithmetic and root square operation is realized.Finally, a new calculator chip C9831 is designed, to which more functions than C9821 are added. This shows that the core technology of calculator design has been mastered.
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