| 摘要 |
PURPOSE:To decrease the number of circuits which are designed by users by providing a circuit in a function macro to perform the separate tests. CONSTITUTION:When the state set signals ST1 and ST2 are set at levels 1 and 0 respectively, a CPU 100 stops its working and the internal input/output buffer circuits 111 and 112 have high impedances. Thus the output of a CPU 100 is electrically separated. The 3-state buffer circuits 4 - 8 can observe the working of a user circuit via the terminals 20 - 28 for output of a counter 2 and the output of the result of an AND circuit 3. Under such conditions, the user circuit is tested with use of the test pattern of the user circuit produced by a user. As a result, the test circuits designed by users are decreased. |
