FORMAT

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Supported DOS versions:	All versions
How easy to use?	Moderate
How safe to use?	Potentially very dangerous
How common?	Very common
Internal or external command?	External

Description

Formats a disk and prepares it for use with DOS

Command Syntax

FORMAT drive: [/v[:label]] [/q] [/u] [/f:size] [/b] [/s]

FORMAT drive: [/v[:label]] [/q] [/u] [/t:tracks /n:sectors] [/b] [/s]

FORMAT drive: [/v:[label]] [/q] [/u] [/1] [/4] [/8] [/b] [/s]

drive: can be any drive, but it's best to leave it to just floppy disks for safety reasons
/v:label assigns a volume label, label, to the disk. In DOS 5+ you are asked to enter a label if you miss this out, but not with older versions of DOS.
/q performs a quick format, but only on preformatted disks (DOS 5+ only)
/u performs an unconditional format (DOS 5+ only. In previous versions this is automatic)
/f:size specifies the size of the disk. size can be 160 (160K), 180 (180K), 320 (320K), 360 (360K), 720 (720K), 1.2 (1.2MB), 1.44 (1.44MB) and in DOS 5+ 2.88 (2.88MB). See Comments for allowed sizes for different types of disk.
/b formats the disk using only 8 sectors per track, even on a disk with 9 or 15 sectors, and leaves space for system files.
/s places system files onto the disk so you can boot from it
/t:tracks specifies the number of tracks on the disk (DOS 3.3+)
/n:sectors specifies the number of sectors per track on the disk (DOS 3.3+)
/1 formats only one side of a floppy disk
/8 does the same as /b

Comments

Most of the options listed here apply only to floppy disks. The /s switch can also be used o a hard disk. Beware of old versions of FORMAT which format the current drive after waiting for a key press. A quick format allows the disk to be unformatted whereas an unconditional one does not.

Allowed sizes for floppy disks

Disk Size	Disk format	Allowed size
5.25"	SS/SD	160KB
5.25"	SS/SD	180KB
5.25"	DS/SD	320KB
5.25"	DS/SD	360KB
3.5"	DS/DD	720KB
5.25"	DS/HD	1.2MB
3.5"	DS/HD	1.44MB
3.5"	DS/ED	2.88MB

It is sometimes claimed (wrongly) that a DS/DD 3.5" disk can be converted to a DS/HD 3.5" disk by drilling a hole in it. This does not work. The magnetic coating on a high-density disk is finer and of a higher quality than that on a double-density disk. High-density disks are only slightly more expensive (or cheaper) than double-density disks which makes this a rather pointless exercise.

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