document updated 16 years ago, on Oct 8, 2008

In earlier versions of Windows, there were sys.com and format /s commands that would make a drive bootable.

Unfortunately, these commands aren't available in newer versions of Windows (the last version that relied on DOS was Win98SE). You need to use newer tools to do essentially the same thing.

Tools

Modern tools include:

Knoppix
Windows XP: right click, format, choose "create an MS-DOS startup disk" (only works for floppies)
Windows utilities
- mbrfix (GUI, GUI)
- mbrwizard (GUI)
- testdisk
- makebootfat
- HP USB Disk Storage Format Tool (works on many different storage devices, not just HP, see screenshot here)

What boot media does this work on?

This works on floppies and internal hard drives.

It ALSO works on external USB hard drives, as well as USB thumb drives. When a modern BIOS boots a USB drive, that drive looks exactly like an internal hard drive. No special USB drivers are needed. (however, if you want to access the contents of other USB drives, other than the one you booted from, then you need to load USB DOS drivers)

Technical details: What changes get made?

A DOS-specific VBR gets written
The core boot files (msdos.sys, io.sys, command.com) are copied over
If the drive has a partition table:
- this particular partition gets flagged as "bootable"
- the MBR gets overwritten with a DOS-specific one