The Boot Record is at the very beginning of a FAT volume. The first few sectors of the volume, before the FAT, are the Reserved Sectors or the reserved area. This area in the Boot Record inform us how large the disk is and contains not only the boot sector but also a backup copy of the boot record. The Boot Record contains a field retaining the information of the sector size for a particular media and the BIOS Parameter Block.
The Bios Parameter Block or BPB contains vital information such as the number of bytes per sector on the disk, sectors per cluster, size of the reserved sectors, the number of FATs, root entries, media type, the number of sectors per FAT, the sectors per track, and the number of heads per cylinder. This information is use by the operating system to properly identify the disk and accurately read and write data into it.
The Data Area of the disk is divided into clusters, files and directories store their data in these clusters. The Root Directory comes immediately after the file allocation table and is formatted like any another directory on the disk.
A partition is divided up into equal size clusters, minute blocks of bordering space. Cluster sizes differ on the type of FAT and the size of partition. ...