| 摘要 |
PURPOSE:To automatically set again an external test mode immediately after the internal information of a ROM is confirmed by checking the confirmation of said internal information by an extent equal to the value set at a modulo register. CONSTITUTION:In an external test mode a mode register 3 is set by a set signal 2 produced by an external instruction and a start signal 4 is active. Then a test mode of a ROM is set via an AND circuit 5 and a switch circuit 7. The internal information of a ROM 6 is delivered to an output port 8 synchronously with a system clock 11 and can be confirmed. At the same time, a counter 12 starts its counting action synchronously with the clock 11 when the signal 4 becomes active. A coincidence detecting circuit 14 produces a coincidence signal 15 when the coincidence is obtained between the value set at a modulo register 13 and the count value of the counter 12 and clears the register 3 via an OR circuit 16. The signal 4 clears the counter 12 and sets again an external test mode. |
