| 摘要 |
PURPOSE:To get rid of a fault such as a data error, etc. caused by a malfunction of the checking circuit, and elevate reliability of the system, by always making certain that the checking circuit is normal. CONSTITUTION:In case when the control circuit 7 is not a checking state, FF10 is reset by the program, and therefore as for the selective circuits 8, 9 the upper terminals 8a, 9a are selected, respectively, and a data signal, etc. are input from the floppy disk driving circuit FD. On the other hand, in case when the circuit 7 is in a checking state, FF10 is set by the program, and therefore as for the circuits 8, 9, the lower terminals 8b, 9b are selected, respectively, and a pseudo signal, etc. are input. In this case, when the program further gives a read command to the control circuit 7, the control signal operates corresponding to the pseudo signal. If the cycle redundancy check of the circuit 7 is normal, the circuit 7 detects a CRC error, reports to the computer MCU, and elevates reliability of the system. |
