| 摘要 |
PURPOSE:To diagnose efficiently and quickly a circuit, by detecting a short signal which is fed from the outside of an asynchronous circuit and storing the circuit information in a history memory as if it is at a time point when a clock pulse is fed. CONSTITUTION:A latch 12 is set by the external input signal 11, and an AND is obtained between the signal oassed through a delaying circuit 13 and the output of the latch 12. Thus a pulse having the length of the delay time is obtained. Then an OR is obtained between the above-mentioned pulse and the signal 11. Thus the signal 11 is converted into a signal having the length of the minimum delay time. The latch 12 is cleared by a detecting circuit 18 that delivers a short pulse by the fall of the converted signal. At the same time, a control pulse is obtained if the signal 11 is short and by obtaining an AND between the output of an AND gate 14 and the inverse output of the signal 11. Then the converted signal is written to a history memory 16. The converted signal is written to the memory 16 with a clock when the signal 11 is long. |
