Formatting Partitions

FORMAT.COM is an external MS-DOS command, located by default in C:\Windows\Command
Hidden Parameter :
Hidden parameter are not documented by Microsoft and is find by users threw experiments.

1) FORMAT /AUTOTEST :
FORMAT /AUTOTEST checks for the existing format of your disk, unless the /U (UNCONDITIONAL) parameter is also used, and then proceeds with an UNATTENDED DISK(ETTE) FORMAT:

DOES NOT prompt for a volume label!
DOES NOT prompt to format another disk(ette)!
NO delay: NO user intervention!
Ends WITHOUT pausing!
After completion, it DOES display disk space statistics.

2)FORMAT drive: /U :
FORMAT drive: /U performs an UNCONDITIONAL format, which DESTROYS every byte of data on ANY hard disk/floppy by overwriting it with zeroes (hex F6h).

3) FORMAT drive: /SELECT /U :
FORMAT drive: /SELECT /U makes a disk(ette) UNREADABLE by filling the system area (sector 0) with zeroes (hex F6h), due to using these two incompatible options together. All other sectors are left intact.