last update 27 April 2008.

NEC 900 / 900c official roms and optional downgrade

here are some of the official roms. latest version for 4.2 (OS 2.02) and for hpc2000 (OS v6.0). they are converted to flashable format.
there are RAM OS images and some other stuff too now!
also available is a special package for downgrading a 900c to hpc2000! that downgrade is v6.0, other versions available on request.
if you want some other version, contact me.

some important information first!

i recommend you read the information below, before continuing to the download at the bottom of this page.
if you have a 900 or 900c with non booting OS then please pay special attention.

on the download page (below) you will be required to select your current firmware information (bootloader and OS) before proceeding to the download.
please try to do it as precisely as you can, and if you have more than one device, do it separately for each of them.

if you have any questions, please contact me at contactchan (at)

what you need to know before flashing.

general information

first thing, there are three main methods to flash a nec 900/900c and two advanced ones. also there is the option for jtagging.

1. update by serial cable. can be used by hpc2000 and cenet bootloaders too, but one word of warning: has been tested only with bootloader version 3.0 and 4.10. (basically, the oldest and the latest ones, lol.)
click here for description

2. update by updater bootloader. can be used on any 900/900c, the only limitation is that your OS has to be bootable and that you make sure you flash an OS version that matches your bootloader version!
click here for description

3. update by C+F keys method. WARNING: can only be used with bootloader version 4.10!!!!!!!!!! (the OS version does not matter)
click here for description

there are two more methods. they are not for the normal user under normal circumstances, however they enable extra access, hacking, etc. or maybe even unbricking.

1. ethernet flash. good for some unbricking. every bootloader has this, hpc2000 and cenet too. serial cable required to initialize the procedure. updated with screenshots!
click here for description
2. load ram OS (boot off CF card!). works with any bootloader, but you don't need the serial cable for bootloaders with a version number higher than 4.5.1, which means 4.5.1-6 and 4.10.
click here for description

+1. as for jtag, this requires quite a few things and should only be used if the bootloader got corrupt. can of course be used on any 900 or 900c.
click here for description

bootloader versions

hpc2000:  3.0, 3.2, 3.3, 3.4 are the known ones. (if you have another version PLEASE let me know! thanks!)  4.4, 4.5.1, 4.5.1-6, 4.10.

bootloader 3.0 has been tested for serial cable flashing, it works as long as you have an original 900 and not 900C or 900C-A (model NO on the bottom). if it is flashed to a 900c/900c-A and then used for OS image flashing then it will not be able to read the CF card right to flash in bootloader mode. so you can only use update.exe (updater bootloader method) or ethernet flash as detailed above. similar to the 4.5.1-6 issue below.
bootloader 4.10 has been extensively tested, works excellent.  this is the only one that can save your 900 or 900c if the OS becomes unbootable for any reason AND you do not have access to a serial cable or can't build one (even though the pinout is known finally!). so this is the recommended one if you want to flash images.
bootloader 4.5.1-6 is lethally buggy, it has a bug that NEC left in and so it does not flash the images right using the C+F keys method (or probably even serial). if you flash an OS image, it will never boot the OS. if you flash a bootloader image, it will become a total brick but jtagging method is now available!.
if you unluckily flashed an OS with this - i think the bug is in CF handling. it can be saved by ethernet flashing. but, accessing the eboot menu requires a serial cable (buying or building one - details are readily available) and platform builder as well.
but good news: you can update this to bugfree 4.10 easily as long as your OS is still booting! on the next page (below) you will see an update package for this.

general advice is that you should update your bootloader to version 4.10 no matter what other version you have right now. (but if you have one that is newer, let me know. i've never seen a newer one.) this is strongly recommended.
if you have hpc2000 and want to keep it, but want to get newest bootloader, you first need to update to using second method, then downgrade while keeping the new bootloader.

last note, i will not make any hpc2000 bootloader image public for reasons but if you want one then contact me and i can send it.

Recommendations to users and troubleshooting

for 900c users:

1. if you have a 900c with bootloader 4.10 and OS 2.02, you do not need to install and flash anything except if you want to downgrade or try a custom rom :) .
the point is that if you have 4.10 you are enabled full access to anything without having to worry.

2. to downgrade, the special downgrade package is recommended as it lets you keep the bootloader (version 4.10).
or try the new ram os for hpc2000 to try it out.

3. if you do not have bootloader 4.10, then you must use the updater method. you are not recommended to leave the older version on your 900c.

for hpc2000 900 users:

1. if you have a 900 with bootloader 3.4 and OS V6.0, you do not need to update your hpc2000 (except for maybe the gwes update available on the nec patch page on this site).
updating the bootloader to 4.10 is strongly recommended though

2. to update a 900 that has a hpc2000 bootloader, to latest version of hpc2000, you need a serial cable, OR you need to update to first and then use the downgrade package.
you would be able to just flash the OS itself using updater method but i would say too risky without bootloader 4.10 installed using the full update.

users with corrupt non booting OS:

1. if it still boots to bootscreen just doesn't boot OS:
you must understand: DO NOT flash a bootloader image at all! or your device might become bricked permanently and only JTAG will help!

there are three common causes:
- either, OS image got damaged. solution: reflash last OS version you had on it.
- or, this was a result of interrupted flashing. solution: reflash with the image you were flashing using C+F keys method or serial port.
- or, there is a mismatch between bootloader and OS version. solution: flash the right OS version.

if you can't sort it out, feel free to write to my email for help.
my email address is: contactchan (at)

2. if it doesn't seem to power up at all, or if you have a serial cable and bootloader stops sending messages to your terminal after a while:
- the bootloader got corrupt, usually as a result of a crash. or you flashed a bootloader update in the wrong way!!
solution: jtag! click here to read how to do it.

OK now if you've read all the above (please do!): continue to the download pages.