FAT16 is [R.I.P.! :-)] the most
used File Allocation Table standard on "Wintel" PCs, recognized by all
MS-DOS releases begining with 4.00, and by all MS Windows versions.
MS-DOS releases older than 4.00
operate with the older FAT12 standard, discontinued. FAT12 was able to
handle partitions up to 16 MB (with a 4 KB cluster size).
FAT16 limitations:
- maximum partition size = 2 GigaByes
(GB) = 2,048 MegaBytes (MB);
- (too) large cluster size, which
wastes a lot of disk space, by allocating 1 cluster to each file on disk,
even if a file is at least 1 byte in length. Another example: a 33 KB file
has 2 clusters assigned on a disk partition with 32 KB clusters, thus wasting
31 KB because 2 files do NOT share the same cluster:
Partition size: FAT16 Cluster size: ------------------------------------------- 0 - 127 MB 2 KB = 2048 B 128 - 255 MB 4 KB = 4096 B 256 - 511 MB 8 KB = 8192 B 512 - 1023 MB 16 KB = 16384 B 1024 - 2047 MB 32 KB = 32768 BBegining with the release of Windows 95B OSR 2.0, Microsoft introduced a new File Allocation Table standard: FAT32, which extends these limits:
- FAT32, first version, supports partitions up to 2 TeraBytes (TB) = 2,048 GB = 2,097,152 MB;
- FAT32X, second version, released begining with MS Windows 95C OSR 2.5, features eXtended support for newer drives larger than 8 GB (with more than 1023 cylinders, 255 heads and 63 sectors), using the new BIOS interrupt 13h extension (on newer Pentium class and above PCs that support this BIOS feature), for a total of 28 bits of addressing a maximum of 137 GB of hard disk capacity. More techno details on FAT32X and the 8 GB BIOS limit:
- IBM's "Getting Beyond the ATA 8.4 GB Limit" page
- The Partition Primer page
- The Partition FAQ page
- Windows 98 Central FAT32 + FAT32X page
- FAT16 + FAT32 explained;
Partition size: FAT32/FAT32X Cluster size: -------------------------------------------------- 0 - 259 MB 512 B[*] 260 - 511 MB 1 KB = 1024 B[*] 512 - 8191 MB 4 KB = 4096 B 8192 - 16383 MB 8 KB = 8192 B 16384 - 32767 MB 16 KB = 16384 B 32768 MB - 2 TB 32 KB = 32768 B [*] = ONLY if using: FORMAT drive: /Z:n!Therefore FAT32 wastes a lot less disk space, preserving speedy disk access the same time.
PROs + CONs:
- Larger cluster size means faster disk access, but more disk overhead (wasted disk space), and less room for stored files.
- Smaller cluster size means slower disk access, but less disk overhead (wasted disk space), and more room for stored files.
Opposite to:
NOTE: The performance hit for using FAT32 depends on the speed of your CPU, disk controller capabilities, and hard disk subsystem transfer rate and access time.
- Netscape Navigator/Communicator v3.0x or newer,
- or Microsoft Internet Explorer v3.0x or newer:
- "Everything you ever wanted to know about FAT-32" MSDN page.
- "Description of FAT32 File System" Knowledge Base article.
- "FAT32 on Preinstalled Systems" Microsoft Developer specs page.
NOTE: You need to register HERE for free before accessing the Microsoft Developer Network Online content! Once you join you'll have access to the entire MSDN library, software downloads, online training, tips and tricks, and special offers.
NOTE:Microsoft Technical Support Online requires a one time free registration! This Microsoft site is a MUST for ALL Windows/DOS users, covering all aspects of installing/working with/customizing your Operating System(s). Microsoft's extensive Knowledge Base web site could be the answer to your OS related bugs, problems or lockups!
NOTE:Microsoft Driver and Hardware Development web site has loads of information on newer PC technologies (like PCI, AGP, USB, FAT32, etc), especially the ones used in the Windows 95/98/NT Operating Systems.
Another OSR2/Win98 FAT32 conversion tool comes also from Microsoft: CVT.EXE [61 KB, free, unsupported]. CVT.EXE requires the user to specify the drive letter to convert. Running CVT without command line parameters displays the help screen.
You canNOT convert a FAT32 partition back to FAT16 using CVT!
NOTE: CVT.EXE requires a minimum of 500 KB of free DOS memory. To avoid error messages like:
"Not enough memory or System resources"
while running CVT, disable the loading of some of your DOS mode devices/TSRs, by adding REM in front of the respective lines in your CONFIG.SYS and/or AUTOEXEC.BAT. Edit your startup files using EDIT.COM in DOS mode, or Notepad in Windows. Reboot when done.
To create FAT32 partitions smaller than 260 MB, or to convert FAT32 partitions to FAT16 (and back):
- with data loss: see the UNDOCUMENTED FDISK parameters below;
- without data loss: get a 3rd party utility like Partition Magic v4.0, a retail program you can purchase from Powerquest's secure web site, or order the shipping release. Partition Magic allows you to create/delete/modify/convert partitions "on the fly", without losing the data on your disk(s). You can even safely copy entire partitions to the destination of your choice (provided you have enough disk space). It is compatible with all popular file system standards, including NTFS (Windows NT), FAT32 (Windows 95 B/C OSR2 and Windows 98) and FAT16 (MS-DOS).
IMPORTANT: Start FDISK or CVT ONLY from the native/real/true MS-DOS mode prompt OUTSIDE Windows 95/98's GUI (Graphical User Interface), NOT from a DOS box/session/window inside Windows!
WARNING:USE ANY OF THESE PROGRAMS WITH CAUTION: BACKUP YOUR DATA TO A SAFE LOCATION FIRST!
3rd party disk partitioning tools that provide support for FAT32X:
- Partition Magic v4.0 (includes Boot Manager).
- Partition Commander v1.0 (includes System Commander Personal Edition).
So far NO disk compression scheme (program) is able to compress/double the space on FAT32/FAT32X partitions.
Download the FAT32 Evaluation Tool, included on the MS Windows 98 Setup cd-rom [56 KB, free]. This Windows 98/OSR2 disk utility shows all your drives/partitions, their characteristics, sizes and the disk space you would save if you decide to convert an existing FAT16 partition/disk to FAT32.
UPDATE:
"Thanks for the FAT32 analysis - very comprehensive and understandable.
I have only one suggestion:
You might consider a mention of
users with Compressed Hard Drives who cannot use FAT32 and for whom Partition
Magic is of little use. Of course, this applies to older machines with
their small hard drives, but I read that the average age of PCs in use
is about 3 years with many machines well past the 5 year mark. Many of
these probably can't or don't run Win9x for various reasons, but for those
who do, the substitute to FAT32 is DriveSpace which comes with Microsoft
Plus! for Win95 [the Desktop Themes and Pinball game are just space-wasting
fluff to those with little hard-drives]. As a result of using DriveSpace
[on a 250MB hard drive] the cluster size on C: is 8,192 bytes and on H:
[C:'s Host drive] is 4,096 bytes. The other caveat - minimize cluster waste
by deleting unused files, zip several files together where appropriate
and send files/programs off to portable drives if possible. If the user
is stuck with a small hard-drive apply a "hard-drive" worthy test to every
file that is added."
This update courtesy of Ojatex
(Ojatex@aol.com).
Below are detailed only the UNDOCUMENTED (hidden) FDISK parameters.
IMPORTANT:
To become familiar with FDISK.EXE's command line switches (the documented
ones anyway), run:
FDISK /?
from any DOS prompt, to display
the FDISK.EXE help screen.
FDISK /FPRMT enables the use of
FAT32 file system on hard disks/partitions smaller than 512 MB, normally
not allowed by default!
NOTE:
Use it with CAUTION ONLY from the native MS-DOS command prompt, NOT from
a DOS box/session, even full screen, inside the Windows 9x GUI!
FDISK x /PRI:ps /EXT:es /LOG:ls
meaning:
x = drive number: 1, 2, 3... etc.
Drive 1 corresponds to the 1st hard disk installed on your machine: C,
D, E... etc.
/PRI:ps = creates a primary partition
of size... (in MegaBytes).
/EXT:es = creates an extended partition
of size... (in MegaBytes).
/LOG:ls = creates a logical drive
in the extended partition of size... (in MegaBytes).
If using FAT16, the maximum size...
allowed is 2,047 MB (2 GigaBytes).
If using FAT32, the maximum size...
allowed is 2,047 GB (2 TeraBytes).
NOTES:
- Only one FDISK "LOG" is allowed per EACH logical drive! Therefore on machines with more than one logical drive, you MUST run an:
- You MUST have Windows 95 B/C OSR 2.x or Windows 98 to use FAT32.
FDISK x /LOG:ls
command separately for each drive in your system.
FDISK /MBR repairs a damaged boot sector by overwriting it with a fresh copy, writing a new Master Boot Record to the boot hard disk without altering the partition table information.
WARNING: Writing the master boot record to the hard disk in this manner can render certain hard disks partitioned with SpeedStor unusable! It can also cause problems for some dual-boot programs (including Windows 95), or for disks with more than 4 partitions !!!
The DEFINITION
of MBR: at the end of the ROM BIOS bootstrap routine the BIOS will
read and execute the first physical sector of the first floppy or hard
drive on the system.
This first sector of the hard disk
is called the Master Boot Record (MBR), or Partition Table, or Master Boot
Block. At the beginning of this sector of the hard disk is a small program.
At the end of this sector is where the partition table is stored. This
program uses the partition information to determine which partition is
bootable (usually the first primary DOS partition) and attempts to boot
from it.
NOTE:
The largest partition MS-DOS begining with release 3.00 and up to Windows
95a OSR1 versions of FDISK can create/recognize is 2 GB (GigaBytes).
The 2 GB partition limit has been
overcome by Microsoft (FINALLY!), begining with Windows 95B OSR2. Named
the FAT32 file system, it supports partitions/drives up to 2 TB (TeraBytes).
Windows NT has its own 32-bit protected
file system called NTFS, INCOMPATIBLE with FAT32!
WINDOWS 95 [retail] AND 95a OSR1 [upgraded with SP1] USERS: THE "MBR REFRESH" ISSUE!
UNDOCUMENTED! There is a problem
when installing a new hard drive on your system under Win95. If you upgraded
from MS-DOS 5.0 (or earlier), your primary hard disk, formatted under your
old version of DOS, contains the MBR (Master Boot Record, also called the
boot sector) written by the hard disk formatting utility (FDISK) provided
by MS-DOS. When you add another hard disk under Win95, you format and partition
it with the Win95's (MS-DOS 7.00) version of FDISK.
This means that each drive was
formatted and partitioned under a different OS. Windows 95 WON'T RECOGNIZE
YOUR DRIVE! There is nothing wrong, don't panic. :) It's "just" another
glitch in the OS, something Microsoft overlooked!
When a drive is formatted/partitioned
under Win95, the MBR tells the OS that the drive is a Windows drive. If
your drive was formatted/partitioned under an earlier version of MS-DOS
(3.0 and up), the drive is recognized as an MS-DOS drive.
All you have to do, is to refresh
the MBR, by running FDISK (the Windows 95 version) with the UNDOCUMENTED
/MBR switch (repairs a boot sector by overwriting it with a fresh copy),
on the old drive. Just run:
FDISK /MBR
C:
The boot record (MBR) will be refreshed
without reformatting the drive!
I presumed that your primary (old)
hard disk has assigned the letter C (single logical partition), and your
new (secondary) hard disk is D (also with a single logical partition).
Change the drive letters if different on your system (and if you have more
than one partition per each hard disk).
This can ONLY be done from the
real mode MS-DOS prompt, after you exit Win95 to MS-DOS (or when you boot
with the "Command
prompt only" option from the bootup menu).
NOTE:
Looks like the "MBR BUG" does NOT affect OSR2 or Windows 98.
If the Win95 OS doesn't recognize
the new drive, then you can ONLY do this after rebooting into the old MS-DOS
OS (using the dual-boot feature implemented into Win95 OS). This means
that you need to have kept your old MS-DOS 6.xx files (including FDISK)
on your primary (old) hard disk.
You also need to have kept the
old drive as primary (master) and setup the new one as secondary (slave).
Reboot your system when done. Your
(newly installed) hard drive should be recognized by the OS from now on.
Now you can change the new drive
to "master" (primary boot drive) and setup the old one as "slave", especially
if the new one is faster.
Sounds pretty complicated, but
you may have to do this some day, and it's better than reformatting the
entire drive, and losing precious data.
There is still another way to refresh
the MBR. Run Win95's Scandisk utility for ALL hard drives on your system.
Scandisk will automatically refresh the MBR on your drives, as needed (if
the MBR is damaged).
IMPORTANT:
Read this related article published
in
Magazine, the August 1996 issue, at the bottom of page 52, under the
"Bug Watch" logo. Title: "Trouble
With Windows 95's Disk Partitioning". It details the same topic above.
Another recommended
article:
"Detect
Buggy Partitions" (from the April 1997 issue).
Check out
web site frequently for online up to date OS info/bug reports.
UPDATE:
There is a great tool that can overcome the above Windows 95 limitation,
and make ANY hard drive compatible with ANY operating system and ANY FAT
system (and much more), called Partition Magic by Powerquest.
Retails for about 30-50 bucks at popular computer stores (it's worth every
penny, it saved my "computing life" more than once).
Partition Magic new version 4.0
supports OSR2/Win98 FAT32/FAT32X and WinNT 32-bit NTFS file system standards.
FDISK /Q prevents rebooting the computer automatically after altering the partition information by using FDISK with other parameters.
FDISK /STATUS displays a screen similar to using FDISK's option 4: "Partition information", but also includes EXTENDED partition information.