Note : You will loose all your data on your ipaq and on your SD card !
       There is also a risk that you irremediably kill your ipaq.
       Now, you are warned, this won't be my fault !
       This has only been tested to update a 1.00 french hx4700 to the
       1.10 english version.

Update 2005/05/09 : There was a mistake in the document : the SD header is 412 bytes, not 2600 as I previously wrote. Thanks to Vadim who found it !

0/ You need :

- a SD card of 256 MB or bigger

- a (usb or serial) (cradle or sync cable)

1/ Make a backup of your current rom

Have a look at 
http://www.handhelds.org/moin/moin.cgi/HpIpaqHx4700OriginalBootloader

Basically, you have to :

- reset in bootloader mode (press Contact + iTask + reset for 2 seconds)

- use a terminal emulator to connect to the ipaq and get the 'SER>' 
prompt

- type 'd2s', press the enter key, and wait (the backup of flash to SD 
card takes many minutes)

2/ extract the rom from HP's update

- get the .exe package from hp.com

- extract it with cabextract (the only important file is the .nbf file)

- type 'dd if=/path/to/.nbf_file of=hp_rom bs=264744 skip=1'

3/ extract the header from your SD backup

Here I assume that your SD card is linked to /dev/sda

Now is a good time to make a backup of your current rom before we 
definitely loose it

- type 'dd if=/dev/sda of=my_backup bs=130M count=1'

- save the my_backup file ! at the end of the process, it will be the 
only way to restore your ipaq to its original state

- type 'dd if=/dev/sda of=my_header bs=412 count=1' And now we have 
the header

4/ build your new rom image

- type 'cat my_header hp_rom > my_new_rom'

- type 'echo -n HTCE >> my_new_rom'

- backup my_new_rom, it will prevent you from having to run the whole 
process again

5/ write the rom to the SD card

- type 'dd if=my_new_rom of=/dev/sda'

6/ flash your ipaq

- insert the SD card in ipaq SD slot

- enter bootloader mode (press Contact + iTask + reset for 2 seconds)

The system should detect the SD card, and ask you to press power to 
flash the backup

- press power

- wait 20 minutes

- hard reset

Your new system should boot now

##########################################
Copyright (c)  2005  Alexandre Boeglin <alex (at) boeglin (dot) org>
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts.  A copy of the license is included in the section entitled "GNU
Free Documentation License".