| 摘要 |
PURPOSE:To shorten the scan processing time by providing a control circuit which checks a selector circuit and a scan register and outputs a scan mode signal to set an optional scan path circuit in a scan operable state. CONSTITUTION:A prescribed state is set to a scan register 124, and a scan path constitution control circuit 121 judges the contents of the register 124 and outputs the selection signals 113-115. Thus a selector 103 connects the output of a scan path 108 to the input of a scan path 107. A selector 104 does not connect the input of the path 108. A selector 105 connects the output of the path 107 to the input of a scan path 109 respectively. When another state is set to the register 124, the circuit 121 outputs a selection signal 116. Then a selector 110 connects the output of the path 109 to a scan path collector. As a result, a single scan processing operation suffices and therefore the scan processing time is extremely shortened. |
