| 摘要 |
PURPOSE:To carry out a test of a substrate containing a CPU by providing a 1st bidirectional gate between the CPU and an internal bus and a 2nd bidirectional gate between an external testing CPU and the internal bus respectively. CONSTITUTION:When a test is given to a substrate 4 containing a CPU 5, an IC plug 9 connected to a substrate test tool 7 is connected to an IC socket 2. Then both connectors 3 and 6 are connected with each other. When a changeover switch 40 is turned on, a bidirectional gate control part 30 sends a signal of an insignificant level to a bidirectional gate control signal 16 to close a bidirectional gate 20. At the same time, a bidirectional gate control signal 17 is sent at a significant level to open a bidirectional gate 21. As a result, the CPU 5 is electrically separated from an internal bus 10 and the tool 7 is connected electrically to the bus 10. |
