There are 2 things you need in order to make an USB flash drive boot into DOS. The first is a boot sector, and the second are the DOS boot files. Below are the steps I used to get these onto a USB flash drive, making it possible to boot into DOS from the USB flash drive.
The following steps where all done in Microsoft Windows XP in a VMware virtual machine. They should work with most other versions of MS Windows.
I successfully used these steps on an USB flash drive I got at Immersion Week 2008 for use in a ZFS demo (Identifies itself as CBM). YMMV depending on USB flash drive model and manufacturer. These steps are based off of the very useful information at BootDisk.com
1) Getting a boot sector on the USB flash drive
Start by gettng the mkbt DOS utility from here mkbt
Unzip mkbt into a temporary directory
OK, if you are like most people these days, you don't have a floppy drive in your laptop or desktop, and you may never have, although you should know what a floppy is if you have any interest in doing this. So, if you don't have a floppy drive in your machine, you can use vfd to create a virtual floppy, which is what I did. You can get vfd from here vfd
, then follow the directions for creating a virtual drive in RAM, then save it as a file for future use. Use the Windows Explorer format menu item to format the virtual floppy and make sure you check off the box to make an MS-DOS start up disk.
Once you have access to a DOS boot floppy, use the following command, from a command prompt, to save the boot sector, where a: is the drive letter of your DOS bootable floppy (virtual or physical)
mkbt -c a: bootsect.bin
Now use the following command to write the boot sector to your USB flash drive, where n: should be replaced with the drive letter of you USB flash drive.
mkbt -x bootsect.bin n:
2) Getting the DOS boot files
copy all the files from the boot floppy onto the USB flash drive.
Now you should have a DOS bootable USB flash drive, for use with a system that supports booting from USB, including x64 products from Sun. Copy over whatever DOS utilities you need to use, including AFU for Adaptec RAID controller firmware updates, which is used in some of Sun's x64 products. Or use it for whatever need you may have. Even with a small USB flash drive, you will have a lot more room than a floppy ever dreamed of. Perhaps my next blog post should be on whether inanimate objects dream. :-)
Update : Per several comment poster's, I have fixed the command line for writing the boot sector onto the USB flash drive. It is now correct in the above post. Thanks to those who caught my mistake. :-)