Running a user program that was written in C/C++ requires a separate program to handle copying of initialized data for inclusion in the target system and to start the user program (main function). This program is called the startup routine.

The user must create the startup routines for user programs. Renesas provides the source code for a startup routine with its integrated development environment (IDE) for the RX Family so that the user has a startup routine that can be adjusted to suit the target system.