| 摘要 |
PURPOSE:To attain data transmission/reception between an incorporated RAM and an external device in high speed by providing a function separating the microprocessor and an internal bus to decrease the testing time. CONSTITUTION:In testing a RAM or a ROM, a level of a control signal BC is made to a high level ahead the conduction of the test so as to separate the microprocessor CPU and the internal bus BUS. Then an address signal is applied from an external terminal to select directly the RAM or the ROM. In case of the ROM, the content is read and extracted externally via an I/O, compared with a prescribed expected value and its propriety is discriminated. In case of the RAM, the content is read similarly, and its propriety is discriminated by comparing it with the written data. The testing time is decreased by testing the device directly from the external terminals in this way and the data is transmitted/received with an external device in high speed. |
