| 摘要 |
PURPOSE:To improve a contacting reliability by providing a buffer gate to open and close between a cpu and a signal bus and providing a connecting means to connect a tool for an external substrate test having the cpu equal to the cpu to a signal bus. CONSTITUTION:When a cpu mounting substrate 4 is tested by using a tool 7 for a substrate test, an IC plug 9 connected to the tool 7 for the substrate test is connected to an IC socket 2, a tool fitting substrate 1 for the substrate test is loaded on the cpu mounting substrate 4 by inserting a connector 3 to a connector 6. Consequently, by the control signal from a cpu separating control part 20 in the tool fitting substrate 1 for the substrate test, a buffer gate 30 is closed, input output signals 12 and 13 from the cpu are separated and a cpu 5 is separated from an internal signal bus 11. On the other hand, the input/ output signal from the cpu built in the tool 7 for the substrate test comes to be input/output signals 14 and 15 from the tool for the test and is delivered to the internal signal bus 11. Thus, the contacting reliability is improved. |
