Update 12/28/10: updated download links.
Previously, I posted a couple small guides on bootable USB drives, but recently I’ve been receiving reports that the utility mentioned in the guides is not working correctly. In all fairness, the utility was created only for use with a certain type of drive, and whoever made it hasn’t updated it, so problems with newer, unsupported drives are unavoidable. A newer, better utility is now available from HP, the HP USB Disk Storage Format Tool. (Don’t worry, it can be used with non-HP drives, verified with my Sandisk Cruzer Mini.) The HP utility will allow you to easily create a bootable USB drive, provided you have a disk available with the proper DOS system files, for example a Windows 98 boot floppy. If no boot disk is available visit bootdisk.com for some downloadable images, or simply use HP’s included DOS files.
To clarify the process, I’ve decided to post an update on how to manually make a bootable USB drive.
First, there are a few system requirements that must be clarified:
- Obviously, your computer’s BIOS must allow booting from a USB device. Most recently manufactured computers allow this functionality.
- You’ll also need a bootable floppy disk or CD. For example, you can use a Windows 98 CD or a Dell Resource CD.
- You will also need a utility with the ability to create a master boot record, create and set active partitions, and format and transfer boot files. The DOS fdisk and format utilities that are present on the Windows 98 CD will handle this perfectly.
- A USB drive that is capable of being made bootable. There are a few that have strange partition structures that do not allow for making bootable partitions. Contact the manufacturer if you’re not sure your USB drive is bootable.
Now that we have all the prerequisites taken care of, let’s get to how to actually make the drive bootable:
- Make the USB drive the first drive in the drive sequence. This is necessary because fdisk will not allow a partition to be active (bootable) unless it’s the first drive. This can usually be accomplished by plugging the drive in, powering on the computer, and going into the BIOS to change the boot sequence. If this is unsuccessful, simply disabling or unplugging the other drives in your system (except the CD-ROM, of course!) will do the trick.
- Boot the computer to a DOS shell from the bootable floppy or CD with the USB drive plugged in.
- Run fdisk.
- Set the primary partition on the USB drive to active by using “set active partition” (option 2) in fdisk. If you don’t already have a primary partition on the USB drive, use fdisk to create one.
- Exit fdisk.
- Reboot the computer to a DOS shell from the bootable floppy or CD with the USB drive plugged in.
- If you want, use the DOS command dir c: to verify the contents of the primary partition on the USB drive.
- Format and copy the boot files to the primary partition using the DOS format /s c: command.
- Run fdisk /mbr to write the master boot record to the USB drive without altering the partition table.
- Restart the computer, this time booting from the USB drive. If everything went well, you should see the C:> command prompt.
If everything didn’t go as well as planned, feel free to post in the forums for help.