| 摘要 |
PURPOSE:To specify the position of a shift register (SRL) when the trouble of SRL is present, by providing bidirectionality to the shift direction of a shift bus capable of performing scan-in/scan-out. CONSTITUTION:A test apparatus has a plurality of SRLs1 being state memory circuits each having shift function and SRLs1 are connected in a chain state to constitute one or more of shift buses 21-24 not only to make it possible to perform scan-in/scan-out but also to provide bidirectionality to shift operation while said shift operation is controlled by a shift direction control means 11. The control means 11 is changed over in its shift direction by the input signal from a shift direction control terminal 12. That is, the control means 11 is a so called switch circuit performing the alteration of the connection order of SRLs1 present in the shift buses 21-24 by the input signal from the terminal 12. By this mechanism, scan-in/scan-out can be performed in either a substantially forward shift or reverse shift direction. |
