USB flash drives have quickly become a de facto replacement for the floppy disk. Aside from having many times more space for holding data than a floppy, USB flash drives are faster, smaller and far less prone to damage. Plus they work on just about any computer with a USB port.
Making a USB flash drive into a bootable drive isn't that easy, which I think has kept flash drives from completely eclipsing the old-school floppy disk. Almost every computer shipped these days supports the ability to boot from a USB device in BIOS, but making a USB flash drive (not an external USB hard drive) into a bootable device requires some fancy footwork.
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A bootable flash drive can be used to perform many tasks. You can use a bootable USB drive as a rescue disk or as a way to do flash upgrades or other system-level changes that require a boot disk. You can also use it to launch applications that run from their own DOS boot floppy without having to put up with the horrendously slow load times of a floppy disk.
To create a bootable USB flash drive, you'll need the following:
- a 3.5-inch floppy disk
- a computer with Windows XP, a 3.5-inch floppy drive and at least one USB port
- Bart's MKBT utility, freeware for copying boot sectors.
The USB flash drive will boot like a floppy and run a DOS command line, so keep in mind that any utilities or files you copy to it will need to work as DOS command-line applications.
To create your bootable USB flash drive:
- Get a blank 3.5-inch floppy (you'll only need to do this part once).
- Insert it into the floppy drive of a Windows XP computer, right-click on the "3 1/2 Floppy" icon in My Computer, and select Format. Be sure to select the "Create an MS-DOS startup disk" option when you format the disk.
- Unpack MKBT into a folder.
Open a command-line window and go to the folder with MKBT. From there, type
mkbt –c a: bootsect.bin
This will extract the boot information from the floppy in A: and copy it to a file named bootsect.bin (which will be written into the folder you're running MKBT from). If you want to create more bootable devices, save this file for future use.
- Plug in the USB flash drive and make a note of what drive letter is assigned to it.
- Format the USB drive as a FAT16 device. The format of the drive must match the format of the floppy; FAT16 will work on any thumb drive smaller than 4 GB.
Copy the bootsector information to the USB drive. To do this, type the following command from the command line you used before:
mkbt –x bootsect.bin f:
This assumes that f: is the drive letter for the USB drive; if it isn't, substitute the appropriate drive letter. Note: Double-check to make sure you're writing to the correct drive, or you might overwrite something important.
- Copy all the files on the floppy disk over to the USB thumb drive. You can also now copy in any additional files you want to have present on the thumb drive when you boot it.
When you boot the USB drive, bear in mind that not all PCs are set to boot from a USB device by default. You will probably have to make changes in BIOS to allow this, and the exact steps for this will vary widely from machine to machine. Some machines require that "Legacy USB keyboard support" is enabled to do this.
In almost every case, you must plug the USB drive directly into the computer -- not through a hub -- to allow it to boot, since devices plugged into hubs are not generally enumerated by BIOS at boot time.
Note: The author of this tip has also addressed the topic of creating a bootable flash drive for Windows 2000.
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- Tip #1: How to change the Windows XP Product Activation Key Code
- Tip #2: Create a bootable USB flash drive -- in a flash!
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- Tip #6: Install Windows Server 2003 silently
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- Tip #9: Windows XP and Windows Server 2003 volume shadow copy service
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ABOUT THE AUTHOR: Serdar Yegulalp has been writing about computers and information technology for more than 15 years for a variety of publications, including InformationWeek and Windows Magazine.