| 摘要 |
PROBLEM TO BE SOLVED: To allow easy rewriting of programs and control constants by making a vehicle-mounted electronic control apparatus have a hardware configuration common to a plurality of vehicle kinds. SOLUTION: In the apparatus, a control program and a program to install the constants into a FROM 4 are stored in a mask ROM 3, a program related to a vehicle control and the constants are stored in the FROM 4. Usually, a switch 11 is set to select the FROM 4 as a start ROM via a ROM switching circuit 10, when rewriting the FROM 4, the switch 11 is switched to select the mask ROM 3 as the start ROM, so that an ECU 1 is connected to an external PC 20 via a communication controller 9 of an information system. Thus, easy rewriting of the FROM 4 with data received from the PC 20 is allowed, and easy changing of the program related to the vehicle control and the constants are allowed without any exchange of a ROM and an ECU itself.
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