What is FAT (File Allocation Table)?

FAT (File Allocation Table) is a part of the DOS and OS/2 file system that tracks the location of data stored on the hard drive.

What is the FAT (FAT12 & FAT16 & FAT32 & exFAT) File System?

When the disk is formatted at a high level, FAT is registered twice. There is a table with an entry for each minor. Each FAT entry has a 16 or 32-bit extension.

The directory listing, which includes the file name, extension, and date, shows the FAT entry where the file starts.

If a file is more significant than a cluster, the first FAT access points to the address of the second cluster. In this way, the file continues until the end.

If a cluster is corrupted, the FAT section is marked as such, and that cluster is not reused.

FAT File System History

FAT was created by Bill Gates and Marc McDonald in 1977 to process records in BASIC.

Intel 8086 architecture was first introduced into the QDOS operating system for S-100 computers by Tim Paterson in August 1980. The FAT file system was the main difference between QDOS and CP/M.

FAT Types

1) FAT12

The floppy disk directory system does not support folder placement. Block addresses contain only 12 bits, making implementation difficult.

The size of the disk is stored as a 16-bit calculation expressed in sectors, limiting the manageable space to 32 MB.

2) FAT16

The FAT32 system has completely replaced the old FAT16 directory system. This new version allows the creation of volumes up to 2TB compared to the 2GB limited by FAT16.

These last batches of systems were wasted. So if the system had to save files, say 2KB, it wasted that by making the entire 32KB cluster.

With a FAT32 system, you use a 4KB cluster that saves system resources. In addition, a slight increase in the capacity of the hard disk is achieved.

The FAT16 directory system has no native security for the file system or compression features, and the boot sector is not supported.

The root folder can only contain a maximum of 512 entries, meaning files with long names can remarkably reduce the number of available entries. FAT16 does not work well with large volume sizes.

3) FAT32

It first appeared in Windows 95 OSR2. Reformatting was required to take advantage of FAT32.

Windows 98 included a tool to convert from FAT16 to FAT32 without losing data. This support was not available in the line of business until Windows 2000.

The maximum directory size in FAT32 is 4 GB, which is troublesome for video capture and editing applications because the files they create easily exceed this limit.

4) VFAT ve FASTFAT

Windows 3.11 introduced a new file system access scheme using 32-bit protected mode, bypassing the MS-DOS kernel.

The BIOS or the hardware of the disk drive is used to do this. This also allowed the use of cache, speeding up access. All of these were called VFAT or virtual FAT.

Windows NT 3.1 provided the same approach but called it FASTFAT.

However, it was natural for Windows NT drivers to use 32-bit protected mode.

It is often confused with LFN (Long File Names) support because it is enabled by default in Windows 95.

5) exFAT

exFAT was introduced in 2006 and was introduced in Windows XP and Vista. As the name suggests, it is related to the FAT file system. It is an evolution of FAT32 that attempts to eliminate certain limitations it offers. However, it only introduces some of the improvements available in NTFS.

The main advantage of exFAT is that it eliminates storage limitations. It can also create larger partitions and offer more than 4GB of directory storage. These features are significant improvements compared to its predecessor, FAT.

On the compatibility level, things differ with NTFS, as Windows and OS X are fully compatible with exFAT. However, Linux is more limited, requires specific software to be installed, and offers incomplete support. Because most can read and write, but it does not allow creating partitions.

Like FAT32, exFAT is ideal for use on flash drives and external drives.

FAT32 is always good as it offers more excellent and better compatibility with a broader range of systems. Therefore, exFAT can be applied in exceptional cases.

FAT File Structure

The FAT directory system consists of four parts:

• Root Directory

It is the leading directory of folders and files.

• Boot Sector

The chapter is usually the first part of the unit. It contains essential information, pointers to other partitions, and the address of the boot routine.

• FAT Region

It contains two copies of the file allocation table.

These are maps of the partition showing which clusters are occupied by files.

• Data Region

It is where the contents of files and folders are stored.

Therefore, it occupies almost the entire section. The size of any file or folder can be expanded as long as there is enough free cluster.

Each cluster is connected to the next by a pointer. If a particular cluster is not complete, it wastes the remaining space.

Limits

Differences Between FAT32 and NTFS

FAT32 is also slightly slower than NTFS, the most commonly used file system on Windows devices.

When compatibility between various devices and operating systems is required, using FAT32 can provide the best results.

However, if you want speed, there are better options than FAT32. NTFS is higher than FAT32, especially in terms of read speeds. Its performance is also better in solid-state drives.

Conclusion

In conclusion, I can say that the evolution from FAT, FAT12 to exFAT marks significant advances in file storage and management. Each version played a crucial role in the development of operating systems and data storage technologies.

Understanding the history and characteristics of the FAT directory system provides valuable insight into the progression of file allocation and management. It also forms the basis of modern file systems. In summary, it contributes to the variety of storage options available today.