How to create startup usb disk to flash BIOS

I needed upgrade my BIOS. When looking into it I've been surprised how long did it took me to find the right tool and to how many issues i run when trying and testing it. Hopefully this post will help others to get it quicker.

Problem

How to create a bootable usb pendrive that can be used to flush Bios

Solution 1 (tested)

This solution is based on: HP Flash Utility - HP USB Disk Storage Format Tool.

To create a USB that can be used to boot a system into old DOS system please follow these steps:

• Download the HP Flash Utility hpflash1.zip and Windows 98 MS-DOS System Files win98boot.zip. 
• Extract and run the hpflash1 installer
• Extract the contents of "win98boot" to a location readily accessible 
• If you want to use the graphical interface HPUSBFW.EXE make sure you modify your PATH so you can run HPUSBF.EXE from cmd. 
• Regardless is you are going to use the command line or the graphical interface make sure you run it 'As Administrator'
• For the graphical installer under Format Options tick the "Create a DOS startup disk" option. Click the "..." button near the empty text box to browse to the location of where you extracted the Windows 98 MS-DOS System Files Verification.

One finished the USB will have these files in only:

 
J:\> DIR /A
  Directory of J:\

05/11/1998  07:01 PM           222,390 IO.SYS
05/11/1998  07:01 PM                 0 MSDOS.SYS
05/11/1998  07:01 PM            93,880 COMMAND.COM
               3 File(s)        316,270 bytes

Solution 2 (found later and not tested)

Download the Unetbootin utility (http://unetbootin.sourceforge.net) and install FreeDOS onto USB drive.

Bios upgrade

Once the USB has been created you need to copy there all BIOS.ROM files you need. Finally restart the system and let it boot from USB. Once you get access to the DOS command prompt you need to follow you BIOS upgrade instruction.

My USB drive before reboot had these following files:

 
J:\> DIR /A
  Directory of J:\

05/11/1998  07:01 PM           222,390 IO.SYS
05/11/1998  07:01 PM                 0 MSDOS.SYS
05/11/1998  07:01 PM            93,880 COMMAND.COM
11/01/2012  05:38 PM                39 flash.bat
11/01/2012  05:16 PM         4,194,304 8225v303.ROM
12/13/2010  04:55 PM           153,824 AFUDOS.Exe

References

1. USB
http://answers.microsoft.com/en-us/windows/forum/windows_7-security/how-can-i-make-a-ms-dos-boot-disk-on-a-cdusb-for/9fd9067a-d327-4ba5-8aca-0f33501b87a4
http://www.bios-mods.com/forum/Thread-How-to-boot-into-DOS-with-a-USB-thumb-drive
http://www.sevenforums.com/tutorials/46707-ms-dos-bootable-flash-drive-create.html

2. Alternative solution
https://www.zotacusa.com/help/index.php/Knowledgebase/Article/View/30/0/flashing-bios-with-afudos

3. Others
http://www.thpc.info/how/showhidden.html