| 摘要 |
<p>A single chip microcomputer having an instruction decoder and a function circuit for example, ROM, RAM, ALU, or the like, is further provided with a parallel input shift register, which receives data from the instruction decoder. Output signals from the shift register are transferred to an external terminal or to a data bus by means of gates upon receipt of a testing mode control signal from a testing mode control circuit. By means of the testing mode control signal, the test output signal of the instruction decoder is sent to the external terminal only during testing by means of direct testing of the instruction decoder, testing is more simplified and testing time is drastically shortened, resulting in an increase in production and a decrease in manufacturing cost.</p> |
