Altera Nios Cyclone II Edition Reference Manual page 11

Altera Corporation
May 2007
In the course of development, you might overwrite or erase the flash
memory space containing the default reference design. Altera provides
the flash image for the default reference design so you can return the
board to its default state. Refer to Appendix A: Restoring the Factory
Configuration for more information.
Reference Manual
Nios Development Board Cyclone II Edition
Overview
1–3