Using Etherboot as a BIOS module


I did do this. It worked for me perfectly. This might not be the case with you. If you don't find a Bios flashing tool for your mainboard, if you are not fluent with creating dos boot disks for Bios flashing, if you fear to loose your mainboard when flashing fails - this page is not for you. No guarantees.

Risk of damage to your mainboard exists!


I own an Elitegroup K7S5A Pro board - cheapo mainboard with onboard integrated sis900 chipset and RPL support. Of course I didn't want Novell bootloading, so I decided to put Etherboot into the BIOS.


If you have an AMI Bios, a recent one preferrably, chances are you could succeed in putting Etherboot into it. At your own risk, to mention it again.


A clean DOS bootdisk (without config.sys and autoexec.bat, optimally) which also has the aminf335.exe on it (at least for me, version may differ), the amibcp75.exe (ask google where to get it, maybe some russian sites carry it :-) and one .zrom file from Rom-O-Matic for the respective network card - in my case for the sis900. btw beware - there were some bugs with the sis900 specially. You will need 256k free on the disk. If that's not possible, you could have the amibcp75.exe on any fat harddrive as well, but ROM and flash utility should reside on the floppy.

  • Boot from this diskette. Use aminf335.exe to extract the current bios to a file on the disk like
    aminf335 /sbios.rom /sbios.rom

    (it worked for me specifying /sbios.rom twice, really).

  • Be sure to get a copy of this disk and put it to a save place, just in case something bad happens.
  • You then need to modify the bios.rom file by adding the etherboot.rom file (let's call it ebsis900.rom for example).
    amibcp75 bios.rom
  • Choose edit bios modules. Locate any module of type 20 (it should have the PCI ID of your network card on the very right hand of the listing) and hit Del to remove it. Then hit Insert and input ebsis900.rom to insert the module. Make sure that the same PCI ID is shown. Activate compression and enter that screen - confirm to save changes. Then you save the bios file and exit.
  • If you have a board with built-in video, you probably don't want to remove the video BIOS, so save the type 20 modules to a disk, and look at them with strings or hexdump -C to see what they're for.
  • If you are very sure what you are doing, you now can flash the new bios.rom file:
    aminf335 bios.rom

    and reboot.

  • You will have to enter setup, load defaults, adjust all values. After the next reboot, if available, F12 should bring you etherboot. Alternatively, you should be able to choose BBS0 as boot device.
  • If you get into trouble as etherboot does not show up here or hit any mistake, please comment to the etherboot users mailing list.

Btw: I succeeded in adding a rom for a non-onboard NIC (namely an Realtek 8169-based Gigabit PCI NIC) too.


This section added by Timothy Legge: Note: I own an Eprom Programmer. I made a backup copy of my bios chip before attempting this. If you don't or you didn't, I am not responsible for your non functional PC.

    • CBROM 1.xx is for Award BIOS 4.5 series only
    • CBROM 6.xx is for Award BIOS 6.0 series only
    • CBROM 2.xx is for Award BIOS 4.5 and 6.0 series
  • Obtain the latest copy of the bios for you motherboard or use the flash utility for YOUR motherboard to extract your current bios:
    flash52.exe /Pn savebios.rom /Sy 
  • Display the current bios format:
    cbrom.exe savebios.rom /D 
  • Note the amount of free space available in the file
  • Add an Etherboot zrom file:
    cbrom savebios.rom /pci sundance.zrom /err
  • Verify that the rom was added:
    cbrom.exe savebios.rom /D 
  • Apparently you can also use modbin6.exe in place of cbrom for Award (and Phoenix?) BIOS.

How to recover from a bad flash:

Using a MB that does boot…

BIOS chips can be removed once the computer has booted (i.e. while it's still running). You can boot using a known good BIOS chip, remove the good chip, insert the faulty BIOS chip and reflash it.

More information

More information can be found in the web, for example on

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