SEMICONDUCTOR INTEGRATED CIRCUIT

PURPOSE:To test a high speed signal stably at the outside by writing a high- speed internal signal into a memory, and performing reading operation at a low speed. CONSTITUTION:A logic circuit 4 receives a control signal 3 from an input circuit 2 and also receives a data signal 18 for tests from a test control circuit 16 as a data input 7 which can be read out and written (RWM). The logic circuit generates an output 9. The output 9 is written into an RWM 8 through an RWM-data input switch 22 under the control of an RWM control output 17 for the test. The verification of the output 9 is performed as follows. The change in state of the output 9 is sequentially written in the RWM 8, and the data are read out of the RWM 8 at a low speed. An RWM data output 14 is sent out through an input switch 24 for an output circuit. Thus the normal/ abnormal states can be judged.