| 摘要 |
<p>PURPOSE:To enable a processing by a new control program only by connecting a ROM storing the new control program to the external part of a microprocessor by providing a circuit to execute the read and decision of a certain external determined address and to generate a control signal at initial time before executing the processing. CONSTITUTION:At the initial time, an external ROM recognition and control signal generation part 5 reads the external specified address, decides the data and controls a built-in ROM gate 2 and an external ROM gate 6. Therefore, the microprocessor itself recognizes whether the ROM is connected in the external part or not, and the reading destination of the control program can be switched to either a built-in ROM or an external ROM. Thus, when the ROM is not connected in the external part, the processing is executed by the control program stored in the built-in ROM, and when the ROM is connected in the external part, the processing can be executed by the control program stored in the external ROM.</p> |
