Hello,
a STR7 USB MassStorageExample for GCC can be found here:
http://www.yagarto.de/projects/str7usbmsd/index.html
The original STR7 USB MassStorageDevice (MSD) example can be
found at the STMicroelectronics page.
I have used this example only in the external RAM, but it should
worked in ROM without the memory extension too.
In this case, you have only 32KB of RAM.
Best regards,
Michael