| 摘要 |
PURPOSE:To detect automatically a failure of a register by the firmware or hardware without requiring the operator by comparing a data stored in the register and the inversion of each bit of the data. CONSTITUTION:A transferred data is inputted from a terminal A of a multiplexer 20 and fed to registers 1, 6 and 11 and one of the data in the registers is selected by an output of AND circuits 2, 7 and 12. Suppose that the register 1 is selected, after the data is stored in the register 1, it is read and when an error is detected by a parity error detecting circuit 5, an error signal is transmitted to OR circuits 3, 17. The signal through the OR circuit 3 is fed to the circuit 2, which makes the register 1 enable, and the signal fed to the circuit 17 makes a register 22 enable via an AND circuit 19. Further, the data from the register 1 is stored in the register 22 via a multiplexer 16. Moreover, each bit of the data is inverted by an NOT circuit 21, the result enters the register 1 by switching operation of the multiplexer 20, and the inverted data enters a comparison circuit 23 via the multiplexer 16 and compared. |
