| 摘要 |
<P>PROBLEM TO BE SOLVED: To reliably detect a fixed fault caused in any bit of an address bus, by making common use of the address bus of an output address bus and an input address bus for designating input-output ports from a CPU. <P>SOLUTION: An output address decoder 13 and a feedback address decoder 14 are connected to the CPU 11 via a common address bus 18. An address for designating a control output terminal of the output address decoder 13, and an address for designating a control output terminal of the feedback address decoder 14 corresponding to it, are inversely set in decoding order. When any bit of the address bus 18 causes the fixed fault in "0" or "1", the input port 16 different from normality is read by the CPU 11, and the fixed fault of the address bus 18 is reliably detected. <P>COPYRIGHT: (C)2012,JPO&INPIT |
