| 摘要 |
PURPOSE: To make the test time largely reducible in the test of a printed circuit board where a lot of large scale integrated circuits are mounted, or at the time when test data are long and large enough. CONSTITUTION: A changeover switch 3 branches input data 2 to an input or output exclusive scannedly buffer. Input serial wiring 13 inclusive of six input scannedly buffers 15a to 15f makes the data scanned successively. Another serial wiring 14 inclusive of six output scannedly buffers 16a to 16f makes the data scanned in order as well. A selector 4 selects either of the input serial wiring 13 or the output serial wiring 14, outputting it as the output test data 8. A control circuit 5 performs timing control through a test control signal 10, a test control signal 12 and a test clock 11. |
