| 摘要 |
PURPOSE:To obtain effective data for the investigation of various faults by freezing a history memory in response to the output change of a gate in a computer system selected according to a scan-out address. CONSTITUTION:An address value is set in a scan-out address register 1 and then a gate 3 is turned off by a mode switching signal to fix its value; and EOR operation is performed by a gate 6 by using the polarity specifying bit in the scan-out address to decide on whether the memory is frozen at the rise or fall of the scan-out value outputted from a selecting circuit 5. The output of the gate 6 freezes the locking of the history memory through an RS flip-flop. Other kind of freeze signals can be selected by mode switching signals 7-9. |
