To run the USB drive before entering the operating system you must perform certain manipulations. Before writing this program, you need to create boot sector. This can be done with the help of additional tools or the shell. First, try the second option.
Click "Run". To do this, press Win (start) and R. Fill out the field with cmd, and press Ctrl, Shift and Enter. This combination allows you to run command prompt with administrator rights.
Proceed to the device selection for creating the boot sector. Consistently enter the command diskpart and list disk, separating them by pressing Enter. Find out the number assigned by the operating system of your flash drive. Select the desired device by typing Select Disk N, where N is the number of the drive.
Now enter several teams, each time pressing Enter:Cleаn; Сreаtе Partitiоn Primary;Sеlect Pаrtition 1;Activе;Fоrmаt FS=NTFS;Amp;Exit.
Now just copy to a USB drive the desired program or utility. Remember that not all programs are able to run in MS-DOS mode. To work with the computer without using the Windows operating system is recommended to use special utilities.
If you want to create an installation flash drive with the operating system Windows Seven or Vista, then insert in the drive the appropriate drive and restart the console. Open the contents of the DVD-ROM drive by typing E:, where E is the drive letter of the drive.
Now type cd boot to navigate to the appropriate folder. Enter the command bootsect.exe /nt60 G, where G is the drive letter of the USB drive, and press Enter. Wait until write boot files on the USB drive.
To automatically create boot sector you can use a special utility such as BootIce.