| 摘要 |
<p>PURPOSE:To make it possible to read out specific information stored in a built-in ROM and to expand an application range by outputting the specific information in a specific address of the ROM to the external by a reset signal inputted from the external. CONSTITUTION:The output data of the ROM 2 are outputted to a system bus 24A and a data bus 25 through an I/O buffer 3. A decoder 22 latches a select signal SL obtained by decoding data from a data bus 25 based upon a reset acknowledge signal RSAK outputted from a microcomputer 10. A selector 23 connects either one of system buses 24B, 24C to a system bus 24A based upon the select signal SL. Since the external circuit can be switched and used in accordance with the specific information read out from the ROM 2, the application range of the microcomputer can be expanded.</p> |
