My status update:
> ...The updater is specific to the v30...So we have to modify the updater to work with the S
> ...Perhaps we can modify the updater to load a modified firmware on the S
You only need to change one byte (hint: change the first unicode "gigabeat V" -> "gigabeat S")
Then the Japanese firmware updater can be used to re-install the firmware on the GigaBeatS !http://www.mygigabeat.com/forum/messages.cfm?threadid=B4FB14C7-3048-2906-EA4E52CB99CE6A7E
NOTE: since there is only one official release, this is good for fixing broken S30/S60s.
It is also good for running 'homebrew' (see below) !!!
> ..and why not on a zune..
The Zune update process is different. The existing ZUNE.EXE windows app can be hacked to update the Zune device. Homebrew not (currently) possible for different reasons.
re: Homebrew on the GigaBeat"S" S30 or S60 (the key to running Linux or RockBox)
The GigaBeatS uses digitally signed firmware. If you change almost any byte in the NK.BIN the SHA-1 hash changes, it fails the signature test, and the image will not be run.
Fortunately the boot loader is not very secure. With a trivial mod to the NK.BIN file, you can disable the check (BTW: 16 bytes)
NOTE: the Zune firmware (all released versions) does not have this hole so this technique won't work :-<
Long story short...17 bytes later the GigaBeatS is now an open platform for writing homebrew, porting RockBox etc.
Next to write a flexible bootloader. Will post details once that is working. I suspect it will be longer than 17 bytes ;->
To keep it non-invasive, you will have to cold boot your GigaBeatS to switch between the different OSs (another advantage of the little battery off switch).