Selectable eight or twelve digit integrated circuit calculator and conditional gate output signal modification circuit therefor

摘要

An integrated circuit calculator which can operate in either a twelve digit or an eight digit mode is provided. A conditional modification circuit modifies some of the memory addresses employed in the twelve digit calculator to provide the eight digit calculator with more random access memory registers than the 12 digit calculator. In the twelve digit calculator, the conditional modification circuit also controls folding of some memory registers in order to minimize the chip area required for the memory circuitry and control logic.