FDISK

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

Prepares a hard disk to be formatted by DOS.

FDISK [/status] [/x]

FDISK /mbr

/status displays partition information
/x ignores extended disk-access support. Use this switch if you receive disk access or stack overflow messages.
/mbr rewrites the master boot record and partition table without changing anything else on the disk. This switch is not documented.
If you miss out the switches, FDISK starts with menus from which you can partition or view partition information.

FDISK can be extremely dangerous if not used properly. The /mbr switch is useful if you are affected by a partition table virus.