Abstract: A testable LSI chip incorporating memory blocks, such as RAM and ROM, and random logic circuitry, and a testing method thereof are disclosed. A front-stage peripheral logic circuit block and rear-stage peripheral logic circuit block connected to the input and output modes of a memory block are provided on their output side and input side, respectively, with the flip-flops in correspondence to the input and output nodes of the memory block. The flip-flops on the output side and flip-flops on the input side are each connected to form a shift register. In testing the front peripheral logic block, the test result is latched in the flip-flops on the output side and then the contents are shifted out for reading. In testing the rear-stage peripheral logic circuit block, a bit pattern for testing is shifted-in and latched in the flip-flops on the input side and then supplied to the rear-stage peripheral logic circuit block under test.

Abstract: In a logic circuit which is logically divided into partial circuits each consisting of a logic block, data holding stages on the input and output sides therof, and a scan circuit segment associated with them, diagnostic data for a logic circuit section is obtained using the scan circuit segments in the respective partial circuits and wherein, only the scan circuit segments in the respective partial circuits are actuated to set values in the output side data holding stages and to read out the contents thereof as diagnostic test data for a scan circuit section.