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Tuesday, 06. October 2015


Howto: BIOS-Update per bootable CD

BIOS Update per bootable CD under DOS



A guidance how to create a Boot-CD (which contains the Freeware version of Caldera DR-DOS v7.03) to perform a BIOS update.

see also: BIOS-Update Howto: step-by-step instruction
see also: BIOS Update per bootable USB-Stick
see also: BIOS Update per DOS-Boot-Diskette


Important: this method simulates/emulates a floppy drive. Due to the size limitation of a 2.88MB floppy disk, you can only use a BIOS file and flashtool whose total file size is max ~2.7MB!

Recommendation: i prefer to use the method BIOS Update per bootable USB-Stick!
A bootable pendrive has no size restrictions and more importantly: you can create a BACKUP before updating the BIOS - and that's always a good idea!


The following tools are needed:

  • CDBurnerXP - free CD-Burning software, Download from manufacturer's website
    Attention: download the CDBurnerXP-Version without OpenCandy! (OpenCandy = Adware!)
  • UltraISO - Trial version, Download from manufacturer's website
  • Ultimate BIOS-Boot-Edition:
    - drdos.img (the boot image file contains the 3 DR-DOS system files, und
    download [1] Ultimate BIOS-Boot-Edition - 5.9MB
  • Flashtool - an executable program (.EXE as file extension), which programs the BIOS file onto the BIOS-Chip, and the BIOS file must be downloaded:
    - Mainboard, bought in its original box: from the mainboard manufacturer website, or
    - Notebook or brand PC: from the notebook/brand PC manufacturer website.
    Both files must be specially designed for the DOS Operation system! If the manufacturer offers only files for Windows, you have to risk the BIOS update either directly under Windows, or you can re-program your old BIOS-Chip, or purchase a new, programmed BIOS-Chip.


New BIOS-Chips (incl. programming) --> in my Shop


Instruction to create a bootable CD

  • Tip: use - if possible - a rewritable CD-RW.
  • Open the Ultimate BIOS-Boot-Edition and extract the boot image file (folder boot_cd) drdos.img.
  • Install and start the Trial version of UltraISO.
  • Open the boot image file drdos.img with UltraISO.
  • Rename the filename of your flashtool and the BIOS file, if they have more than 8 characters (not the file extension!).
  • Copy the flashtool and BIOS file (with Drag&Drop) to the other existing files (see picture).
  • Save the boot image file and close UltraISO.
  • Start CDBurnerXP and choose Data disc:
  • In the CDBurnerXP main menu Disc choose the entry Boot options...
  • In the following window (see picture) enable the checkbox Make disc bootable and insert the path to your boot image file drdos.img.
  • Change the Emulation type to Floppy 2.88MB.
  • Click the OK-Button to close this window.
  • Now you can use Ctrl+B to burn the CD.
The DOS system files are normally invisible, because their file attribute is set to hidden. If you would like to show these hidden files, you have to enable the option: "Windows-Explorer / Tools / Folder options / View / Show hidden files and folders" and to disable the option "Hide protected operating system files".


Starting the BIOS-Update from CD-ROM

  • First, go into your BIOS-Setup and change the Bootsequence to CD-ROM (search for an option like Bootsequence, First Boot Device, or something similarly).

  • Insert the CD and restart your PC. If all went well - DR-DOS starts and you can see the famous DOS-Prompt (A:\>).

  • Now you can start the BIOS update, but remember: you can't backup your old BIOS version onto a CD! But if your harddisk has a FAT16- or FAT32 partition, it would be a good idea to copy your 2 BIOS files to this partition, and to start the update/backup from your harddisk.

  • See also: BIOS-Update Howto: step-by-step instruction

Happy flashing!


User-Comments: BIOS Boot-CD

When I try to drag my 4mb flash/rom file the system says the "disk image is full" so I cannot add the files I need.

Jim 2.Oct.2015 22:19

IF you are receiving the hresult error that HARA Mo mentions above, download and run the portable free version of deep burner. Worked like a charm for me.

Christoballer 8.May.2015 00:15


biosflash 11.Apr.2015 09:34

This does not work my freaking bios file is 16,384kb the iso image programs says the disc is full wtf so how can i do this?

Rik 11.Apr.2015 07:41

@Rodger Grady
Don't insert date + time, press ENTER. You can also try another keyboard.

biosflash 6.Mar.2015 09:41

I was able to make the disc and booted fine. Then it asked me to put in the date and time. The numb lock doesn't work and nither do the fkeys. What do I do know??

Rodger Grady 6.Mar.2015 09:35

@Hara Mo, @palxgr : Same problem here as well. This really sucks.

hdh 26.Feb.2015 03:45

@Hara Mo I have the same problem. Were you able to resolve it? P

palxgr 11.Jan.2015 14:47

Dear, I cannot succeed to burn the cd, it says : 'you did not add any files to the compilation. Do you want to burn the disc anyway? I click yes. Allow making changes to the disc later is selected (but tried also 'prevent further changes to the disc(finalize)'. Clicekd burn disc, then an error occured: most likely the disc is not usable, it's a brand new dvd disc, first tried with two old rewritable cd , same error. error detail: Hresult: 0x80040295

Hara Mo 30.Sep.2014 20:03

Thanks you so much! I was struggling to upgrade my Gigabit P55 motherboard bios as i have 64bit windows 7 and no floppy drive. I tired heaps of ways and couldn't get it to work. Your method above (except the burner software) worked like a charm! Thank you for providing a great community service! Maybe think about adding a "Donate" button to donate through paypal as i certainly would!

Aaron 24.Sep.2014 01:59
 (3 chars)


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