Before making your USB key bootable, be aware, that your USB Key will be deleted completely.  So a backup would come in handy.

Using DOS or Windows 98 you need to install drivers first, to access the USB key. For DOS there is http://www.pocketec.net/downloads.taf?f=pockey1DosDrivers.

For Windows 98 you will find the drivers on the http://www.memorykeytools.com/. Memorykey Tools site. As soon as these drivers are in place, you simply format the key with this syntax:

format /s M:

(replacing M: with the drive letter, that you USB key got assigned.)

For Windows 2000/XP there are a couple of tools you can use.

The easiest is the MBRTool, that the http://www.memorykeytools.com/. Memorykey Tools site used to provide. I still keep a copy around of it http://www.marlow.dk/tech/src/mbrtool.zip here. The tool formats your key in harddisk mode and installs a FreeDOS kernel on there (with FAT32 support).  Downside of this tool is, that it seems to have trouble with USB keys at the size of 256MB or bigger.

Another solution is the http://h18007.www1.hp.com/support/files/compaqbusinesspcs/us/download/20306.html. HP USB Disk Storage Format Tool. This tool seems to work with bigger storage keys, but needs a floppy or the files from a floppy in a directory to copy on the usbkey, to make it bootable.

On Linux you just need to load the usb-storage module.

To format the drive in superfloppy format, you simply do:

 mkdosfs -I /dev/sda

Formatting in harddisk requires more steps, if it’s not allready formatted that way:

 dd if=/dev/zero of=/dev/sda bs=512 count=1

to erase the start of the USB Key.

After that you can do a:

fdisk /dev/sda

and create a new FAT partition (FAT16 is suitable). To install a MBR and format the key afterwards, do:

install-mbr /dev/sda –force
mkdosfs -I /dev/sda1

Now the USB key is ready to be loaded with systemfiles. If you use FreeDOS, MS-DOS, IBM-DOS or DR-/Novell-DOS is up to you.