| 摘要 |
PURPOSE:To reduce the number of signal lines for supervising by informing processor down utilizing unused time of a common bus. CONSTITUTION:When a cause 213 of processor down occurred, a processor down signal forming circuit 210 outputs pulse of 1 clock width that becomes a processor down signal only when a bus busy signal 43 that indicates a common bus 4 is in use is off. The pulse signal of a processor down output 214 makes a processor down signal line 41 effective through an inverter 211, and pulse of a down processor number 215 makes an address signal line 42 selected by a change-over switch 212 effective. Other processor down detecting circuit 22 detects that the signal line 41 is made effective, and outputs a request 101 for interruption by processor down to a processor not shown in the figure, and at the same time, sets the downed processor number sent on the address signal line 42 of a down processor number display register 23 to a flip-flop 231.
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