File systems

 The sole purpose of logical formatting is to place a file system on the disk. Your operating system determines what file system is available to you; you rarely get a choice. The most common file system for machines driven by INTEL processors are: 

·  FAT (File Allocation Table) ----- The standard files system for DOS and Windows. Because of its widespread use, FAT is also accessible by Linux, OS/2, Window NT, and other operating systems.

 ·VFST (Virtual File Allocation Table) ------ a protected-mode version of the FAT file system, used by window’95. it is compatible with the FAT system, the main difference being support for long filenames.

 · NTFS (NT File System) ----- Windows NT’s native file system. You can install Windows NT on a FAT partition, but NTFS is far more advanced, with batter security and reliability, faster file access, and very little wasted space.

 · HPFS (High Performance File System) ----- OS/22’s native file system. As with NTFS, which evolved from HPFS, the security, reliability, speed, and efficiency are far superior to FAT’s.

 · FAT32 (32-bit File Allocation Table) ----- included with window’95 ORS2, a version that is only available preinstalled by the system.manufacture.FAT32 gets rid of many FAT limitations. But so far, it can’t be accessed by anything other than window95 ORS2.

Partitions, and Partitions?

If you’ve played with fdisk at all, you’re probably familiar with primary, extended, and logical partitions. Primary and extended are major partition types and the total number you can have on your hard disk is limited. Note that these limitations have nothing to do with the operating system. They stem from a decision, made by drive and BIOS manufacture in the early years of hard disks, that four partitions should be enough for anyone (a bit like DOS’ 640k memory limit). The extended partition was developed in response to the need for the more than partitions. An extended partition can itself be divided into as many logical partitions as you wish; in a sense, the extended partition acts as a container for them. In a system with multiple operating system, it’s common to have a primary partition for each OS and an extended partition, subdivided into three or four logical partitions, for the OS you use more frequently.

 In the DOS/Windows’95/Windows NT world, drive letters are assigned according to partition type. When your computer boots, it checks the master boot record, which is usually on the first sector of the first disk, and read the partition table in the record. The partition table the computer how the disks are partitioned and the operating system assign letters accordingly. The designation A: and B: are reserved for the floppy disk drives and the active primary partition (only one can be active) on the first hard disk is assigned C: now the first primary partition on each additional hard disk gets the next letter in sequence. Once the primary partition on all hard disk have been assigned letters all logical partition on the first hard disk take their turn, followed by all logical partition on the second disk and so on. If you add a new hard disk to single-drive system that had volumes designed C: and D:. the new disk’s primary partition becomes D: and your old D: becomes E:. Note that the OS will assign letters only to partitions it recognizes, so DOS/Windows95 will ignore an NTFS partition.