Processing circuit having an error detecting and correcting circuit therein

摘要

A processing circuit for receiving input data having an error detecting and correcting code from a data bus is disclosed, that includes a write data latch circuit connected to the data bus for latching the input data; an error detecting and correcting circuit responsive to an output signal from the write data latch circuit for checking the data and correcting the latched data and outputting an error correction signal when the latched data is erroneous; a register circuit for storing correct data sent from the error detecting and correcting circuit; first and second input data latch circuits each of which is connected to the data bus and the register circuit for temporarily latching the input data from the data bus in the absence of the error correction signal, and for temporarily latching the correct data in the presence of the error correction signal; and an arithmetic unit circuit responsive to the input data latched in the first and second input data latch circuits for executing an operation on the input data and responsive to the correct data latched in the first and second input latch circuits for executing the operation on the correct data. The arithmetic unit circuit first executes an operation on unchecked input data while the input data is checked by the error detecting and correcting circuit, and then executes the operation on the correct data sent from the error detecting and correcting circuit only when the input data is erroneous. High reliability of data is thereby achieved without substantially decrease of a program execution speed.