This HOWTo has been contributed by Gerald J. Normandin Jr. It has been found at: http://www.rot13.org/~dpavlin/zaurus.html#ToC5
How to upgrade ROM on Zaurus 5600 without loosing your data?
You have heard instructions about upgrading the ROM which include CF card and pressing C and D? For start, those aren't applicable to Zaurus 5600 because original Sharp documentation said that you have to press Q and T but, I couldn't get that to work eater.
However, you can use Maintenance menu to perform same task (and save your data) like this: Prepare your CF card
You will have to have following files on your card:
initrd.bin mversion.bin updater.sh zImage.bin
I suspected that updater.sh is the crucial component, and I got it from Sharp ROM 1.07 or 1.10 (both have file with same md5sum). However, now you can peek inside this shell script thanks to Sash's encsh.c which works like a charm on this file. Compile encsh with make encsh, do encsh -d updater.sh and take a look inside ... File mversion.bin has version which will be displayed in System Info.
All other files for ROM 1.00 (initrd.bin, mversion.bin and zImage.bin) you can take from Sharp community site.
Preliminary benchmarking of ROMs 1.00, 1.07 and 1.10 shows that writes to flash with ROM 1.10 is about 257.89% slower than with 1.00 or 1.07. Maybe that's why Sharp is delaying it's release... Flash your ROM
1. Insert the CF card to the SL-5600, and connect AC adapter 2. Push Reset button 3. Close the battery cover, and move the Lock Switch to the Lock position 4. Press ON Key while pressing OK key 5. The Maintenance menu will be displayed:
http://www.oesf.org/howto/images/maint-menu-s.jpg 6. Select "4. Update" by using cursor keys and push OK key 7. Select medium from which you want to load update (in my case, "2. CF") 8. Select "Yes" button by pressing left cursor key, and push OK key 9. You will get Zaurus CF updater which will display percentage of kernel and flash (initrd) update. Much better than blinking LEDs! 10. Zaurus will reboot automatically after flashing is over... 11. The Sharp logo will be displayed after a few seconds, and after about 2 minutes, Welcome screen will be displayed.
Procedure is also clever: it will warn you if you don't plug your Zaurus in AC adapter.