Also available for RT-11, 86-DOS, MS-DOS, PC DOS, OS/2, AmigaDOS | ||
In computing, format, a command-line utility included in 86-DOS, MS-DOS, IBM PC DOS and OS/2 and Microsoft Windows operating systems, carries out disk formatting. The command is also available in the DEC RT-11 operating system.
The command performs the following actions by default on a floppy disk, hard disk drive, solid state (USB), or other magnetic medium (it will not perform these actions on optical media):
- clearing the FAT entries by changing them to 0x00
- clearing the FAT root directory by changing any values found to 0x00
- checking each cluster to see if it is good or bad and marking it as good or bad in the FAT
Optionally (by adding the /S, for "system" switch), Format can also install a Volume Boot Record. With this option, Format writes bootstrap code to the first sector of the volume (and possibly elsewhere as well). Format always writes a BIOS Parameter Block to the first sector, with or without the /S option.
Another option (/Q) allows for what Microsoft calls "Quick Format". With this option the command will not perform steps 2 and 3 above. Format /Q does not alter data previously written to the media.
Typing "Format" with no parameters in MS-DOS 3.2 or earlier would automatically, without prompting the user, format the current drive; however in MS-DOS 3.3 and later it would simply produce the error: "required parameter missing".
Any storage device must have its medium structured to be useful. This process is referred to as "creating a filesystem" in Unix, Linux, or BSD. Under these systems different commands are used. The commands can create many kinds of file systems, including those used by DOS, Windows, and OS/2.