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 Post subject: Make a DOS bootable USB Flash Drive
 Post Posted: Wed Oct 22, 2008 4:40 pm 
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While most users don't have any reason to run MS-DOS these days, as a PC technician I find myself using DOS frequently for many reasons. These include updating the flash ROM BIOS or DMI data in a motherboard, running specialized diagnostics that must access the hardware directly, formatting drives with FAT32 partitions larger than 32GB, and some data recovery situations. Normally one would boot DOS using a floppy disk, but few systems these days have floppy drives, and some BIOS images are too large to fit on standard 1.44MB floppy disks. The solution is to use a bootable USB flash drive, which can contain much more in the way of BIOS images, utilities, and diagnostics than would fit on a floppy disk.

The easiest way to make a DOS bootable USB flash drive is to use the HP USB Disk Storage Format Tool, which does most of the work for you: http://www.pcworld.com/downloads/file/f ... ption.html

When using this tool, you'll need a set of DOS boot files, which the tool will copy to the flash drive during the format. In most cases you will want either MS-DOS version 6.22, 7 (Win9x) or 8 (WinMe). I usually use one of the latter two as they also support FAT32, which can be useful. You can get DOS boot disk images from http://bootdisk.com or generate one on your own. For example, you can generate the necessary MS-DOS 8.0 boot files on a system with a floppy drive that is running either Windows XP or Vista as follows:

    1.) Insert a floppy diskette into drive A:

    2.) Open a command prompt and format the floppy with the "/u" (unconditional) switch, which forces the format utility to fully overwrite the entire diskette, generating a clean master boot sector, file allocation table, and root directory in the process:

    Format A: /u

    3.) Open Windows Explorer, right click on the A: drive, and select Format.

    4.) Check the box marked "Create an MS-DOS startup disk", and click Start.

When using the HP USB Disk Storage Format Tool, check the boxes marked "Create a DOS startup disk" and "using DOS system files located at", and then point it to the A: drive as a source for the MS-DOS files. For future formats, you can copy the system files (io.sys, msdos.sys, and command.com) from the floppy or the bootable USB flash drive to a folder on your hard drive, after which you can point the HP tool there in the future. Note that to view and/or copy the system files, you'll need to have Windows Explorer set to view both hidden and operating system files.

If you want to make a DOS bootable USB flash drive the hard way, using only standard Microsoft tools and utilities, you'll need a bootable DOS floppy or optical disc with the FDISK and FORMAT commands included, after which you can follow the directions here: http://support.gateway.com/s/USB/550266 ... aq18.shtml

Bottom line: While there are several methods you can use to create a DOS bootable USB flash drive, using the free HP tool is generally the easiest and fastest method. In addition, you can have several different versions of OS boot file sets to choose from, thereby easily creating bootable flash drives using any version of DOS that you wish. Scott.

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