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What is ROMization? Why is it needed?

Latest Updated:04/01/2006

Question:

What is ROMization? Why is it needed?

Answer:

Application programs used in microcontrollers are ultimately written to some kind of on-chip ROM (mask ROM, flash memory, etc.), and the microcontrollers are then embedded in the application system.
Consequently, it is not enough simply to create and compile C-language programs.
Besides just placing programs and fixed data into on-chip ROM, other items such as data to support variables that have initial values must be programmed.
For example, variables that have initial values must be placed in RAM when starting an application program so that they can be referenced or modified as necessary.
However, the contents of RAM become undefined when the power is supplied to the microcontroller.
Consequently, before starting an application program, initial values must be set for certain variables.
This processing is called ROMization, which means storing initial value data in ROM so that it can be copied to the corresponding RAM at startup.
ROMization is a standard feature in 78K Series products, but it must be specified as an option in V850 Series products.
Also, code (using the to _rcopy function) to copy data from ROM to RAM must be included in the application program.
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