FORMAT.COM HIDDEN PARAMETERS
 
 
 
IMPORTANT: To become familiar with FORMAT.COM's command line switches (the
documented ones anyway), run:
FORMAT /?
from any DOS prompt to display the FORMAT.COM help screen.
 
 
1. FORMAT drive: /AUTOTEST [MS-DOS 5.00 and above ONLY]
 
 
This parameter makes FORMAT.COM check for the existing format of your disk,
unless the /U (UNCONDITIONAL) parameter is also used [MS-DOS 5.00 and above
ONLY], 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.
WARNING: This works on BOTH hard and floppy drives!
 
 
2. FORMAT drive: /BACKUP [MS-DOS 5.00 and above ONLY]
 
 
This FORMAT.COM parameter works exactly like /AUTOTEST, but it DOES prompt the
user for a volume label, and it DOES display disk space information upon
completion.
 
 
3. FORMAT drive: /SELECT [MS-DOS 5.00 and above ONLY]
 
 
This FORMAT.COM parameter is similar to using the MIRROR command [a MS-DOS
5.00 and earlier ONLY utility], and reads the disk(ette) system area (sector
0).
In MS-DOS 4.0 FORMAT /SELECT has the same effect as FORMAT /BACKUP. [Thank you
William Levak (wlevak@cyberspace.org)!]
NOTE: Microsoft removed MIRROR.COM from all MS-DOS releases begining with
 6.00.
 
 
4. FORMAT drive: /U [MS-DOS 5.00 and above ONLY]
 
 
This FORMAT.COM parameter performs an UNCONDITIONAL format, which DESTROYS
every byte of data on ANY hard disk/floppy by overwriting it with hex F6h.
WARNING: You canNOT UNFORMAT a disk(ette) formatted using the /U option!
 
 
5. FORMAT drive: /SELECT /U [MS-DOS 5.00 and above ONLY]
 
 
This particular combination of FORMAT.COM parameters makes a disk(ette)
UNREADABLE by filling the system area (sector 0) with zeroes, due to using
these two incompatible options together. All other sectors are left intact.
[Thank you William Levak (wlevak@cyberspace.org)!]
WARNING: DO NOT use these two FORMAT switches TOGETHER on ANY drive!
 
 
6. FORMAT drive: /Z:n [Windows 95B OSR 2.0 + MS-DOS 7.10 and above ONLY]
 
 
FORMAT drive: /Z:n formats a FAT32 drive with a cluster size of n times 512
Bytes. Meaning:
drive: = your hard drive letter: C:, D:, E:... etc.
n = number of sectors per cluster multiplied by 512 (cluster size in Bytes).
Examples:
n = 1 creates a 512 Bytes cluster;
n = 2 creates a 1024 Bytes (1 KB) cluster;
n = ? creates a ? x 512 = ???? Bytes (???? bytes : 1024 = ? KB) cluster.
You can modify the size of the allocation units (sectors) on a FAT32 drive to
your heart desire.
WARNING: It is recommended NOT to change the default cluster size, because
  some programs such as disk-repair/anti-virus tools might STOP
  working properly!