USB Eulogies
Make That USB Drive DOS-Bootable
Bootable USB!

It's a fact that any storage device can be made bootable. We're used to systems booting from hard disks, floppies, CD-ROMs and even DVDs, but it's only recently that the PC's BIOS has supported booting to a USB device. So if the target system doesn't support USB booting then the following won't work. Time to buy a new system. More on checking the BIOS later.

The easiest way to get the boot files for a bootable USB drive is to steal them from a bootable floppy. So prepare a boot diskette to the desired specification. Note here we are referring to MS DOS-based disks, like the venerable Windows 98SE Setup disk and others of its ilk.

The next task is to rip the boot files from this floppy, for which I currently have two methods. Method 1 is more akin to treating a USB drive like a bootable floppy and most users will agree that it is the easiest. However I will leave Method 2 (which treats the USB drive like a bootable CD) below for any users who might have a special reason for needing it.


Method 1

Download HPUSBFW.EXE [432KB] which is a utility from Hewlett Packard for formatting and making bootable USB drives (thanx Millie!). The file requires no installation and is designed for HP equipment, although it ran on all non-HP equipment and drives tested. The original link for the file is here.

Double clicking on the file runs the app..

HP USB For Windows in action..

Note the utility automatically detects the USB drive. Select the FAT file system, give it a Volume label if required, select Quick Format, select Create a DOS startup disk and point the location to a bootable floppy on drive A:\

The utility will format the drive and copy the boot files io.sys, msdos.sys and also to the USB drive..

Change View options to see the files..

Note that to view these files under Windows Explorer, go to Tools | Folder Options | View tab | Check Show hidden files and folders, uncheck Hide extensions for known file types and uncheck Hide protected operating system files..

Change View options to see the files..

Add more DOS files and hardware drivers to the USB drive, as required. Finally configure the PC's BIOS to boot to the USB drive first.

Method 2

This method uses a little utility called MKBT [29KB] from m'mann Bart Lagerweij over at NU2 Productions (top bloke, that Bart). Open a Command Prompt Window (Start | Run | cmd), navigate to the directory where MKBT was extracted, and type the command:

mkbt -c a: bootsect.bin

D:\Downloads\mkbt20>mkbt -c a: bootsect.bin
* Copy bootsector mode (-c)


Note that "a:" represents the drive which holds the bootable floppy. Once the command prompt returns, there will be a boot sector stored in the file bootsect.bin - coolerino!

Preparing the USB drive

Format the thumb drive in the same format as the floppy disk, which is usually just plain old FAT. FAT32 is better, but many USB thumb drives seem to have an aversion to it. The foul deed can be performed through Windows Explorer - remember formatting destroys all data so copy it elsewhere first. Right click the drive letter of the thumbdrive and select the option Format. Choose the file system of choice (i.e. FAT) and click Start. Goodbye files..

Copying the boot sector file to the USB drive

Still got that command prompt window open? Good, 'cos we're back in black once again. This time the command is:

mkbt -x bootsect.bin I:

like this..
D:\Downloads\mkbt20>mkbt -x bootsect.bin i:
* Expert mode (-x)
* Warning different filesystem ID
Size=0bytes OEM="(=_[sIHC" VolLabel="NO NAME" FileSys=""


Don't stuff up the drive letter which is shown above as I:. Yours is likely to be different. All being well, after the smoke has cleared you will have a bootable boot sector on your thumbdrive.

The Last Bit

The above has basically given the USB drive the equivalent of io.sys, msdos.sys and all in one neat little .bin file, just like a bootable CD-ROM really. Now add any further useful external DOS command files and utilities and any required drivers. Note that if the donor boot floppy had an autoexec.bat or any other batch (*.bat) files or a config.sys, check if these files are using absolute paths (i.e. A:\...) or relative paths (i.e. \...) and change any commands to the latter. Any reference directly to the A: drive will screw things up big-time during boot 'cos it won't be the A: drive any more.

The Last Last Bit (promised BIOS check)

Reboot the computer and go into the BIOS. Such entry is usually granted to those few who can successfully remember the required special keyboard sequence, usually "Del", but popular variations include "F1", "F2", "Insert", "F10" or using all your fingers and toes at once. A bit like Twister but much less fun, especially if you're just playing with yourself..

But moving right along, look for a BIOS setting referring to the Boot Order or something similar. For some reason many BIOS's refer to USB/thumb drive as a "USB Removable Floppy Disk" or "USB Zip Disk" or maybe you will find a uniquely creative variation. Anyway this is the one to be first in the boot list.

If, despite your best efforts and considerable fiddling, your PC's BIOS does not seem to support booting to USB, you could check to see if there's an update for the BIOS chip which would confer this functionality. However note that flashing a BIOS is fraught with danger and if not perfomed exactly as instructed, can result in a thoroughly cactussed BIOS chip (I know, I've been there and so have a few chums - no names of course. Ian.)

Have fun USB booting!
- A.

Put 30.01.2006 | | Refresh Page |