Unreadable iPod

[Nermal]

As mentioned in this thread (http://forums.macrumors.com/showthread.php?t=74064), I copied some songs onto a friend's iPod from my Mac. But now his PC says that the iPod isn't formatted. Apparently he can wipe everything and get it working again, but he obviously doesn't want to do that. Any idea why it's not working?

Sorry, I don't have any technical details as to what's happening, I only have the comments he made today at lunch.

[robbieduncan]

When you wiped the iPod to start from scratch on your Mac it will have formatted the iPod with HFS+ (Mac file system). To work with Windows he needs it to be formatted with FAT32 (Windows file system). There is no way to do this without losing everything on the drive (but not the firmware update that has been applied).

Solution:
Use a window PC to reinitialise the iPod.
Hook it up to your Mac.
Re-sync without reinitiasing (as Macs can read/write Fat32)

[Nermal]

Why do they use different filesystems? And what does it come formatted as originally (ie. at the factory)?