Circuit for the ability to test.

摘要

PURPOSE:To efficiently input and output the storage contents, and to easily and quickly execute independence of a function block and a combination test of the block by scanning each separate group register of every function block, and also, controlling an output and an input. CONSTITUTION:Shift registers 111 - 114, 121 - 124 of every group of a block 1 through a function circuit 11 and an input/output control circuit 12 of a function block 1, and shift registers 141 - 144, 131 - 134 of every group by a combination of the blocks 1, 2 are scanned by the corresponding internal scan buses IB 2, 4 and 6. An input and an output based on this scan are controlled by tri-state buffers P11 - P14 controlled by a decoder 30. The block 2 brought to scan control independently from the block 1 is also the same, and an input and an output of the storage contents are executed efficiently.