| 摘要 |
PURPOSE:To set a desired internal input value for an integrated circuit to be diagnosed and to observe an internal output value directly by providing a control circuit consisting of a T type FF and a selector in front of the input of a shift register and behind the output and controlling whether or not scan-in data and scan-out data are inverted. CONSTITUTION:A bit pattern which is inputted from a scan data input terminal 5 is inverted alternately by the T type FFs 2a and 2b and selectors 3a and 3b and inputted to the shift register consisting of scan FFs 1a-1z which function the shift register, and then desired scan data can be inputted to the internal input of a combinational circuit. Further, when the internal output of the combinational circuit is scanned out through the shift register, the internal output value of scan data can be observed directly at the output terminal 9 while the arrangement of bits inputted to the shift register is maintained.
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