| 摘要 |
PURPOSE:To detect quickly a double selection phenomenon of a common bus and to prevent the effect of the double selection from expanding in a wide range, by connecting successively the data transfer devices at both the selecting side and the side to be selected via detecting signal lines and then connecting these lines to a detection control part. CONSTITUTION:A data transfer device 20 at the selecting side and data transfer devices 21-1 and 21-2 at the side to be selected are connected successively via detecting signal lines 23-1-23-4. Thus a circular signal transmission line is formed. The signal lines 23-1 and 23-2 are connected to a detection control part 22, and the output side of the part 22 is connected to the signal lines 23-2 and 23-3 led to the following transfer devices. In the same way, the output side of the control part 22 of the final one of those transfer devices connected successively is connected to the line 23-4. Then the device 20 checks the signal of the line 23-4 at a proper time point after transmission of a selected address. Thus a double selection phenomenon can be detected.
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