Boot Sector

The boot sector contains some important information. In particular, it identifies the type of disk as well as various facts about the disk. Represented using a C struct, the boot sector looks like the following: [HF94]

struct boot_rec               // boot record
{
   char jmp[3],               // jump instruction
        oem_name[8];          // OEM name
   UINT bytes_per_cluster;    // bytes per cluster
   char sector_per_cluster;   // sectors per cluster
   UINT res_sectors;          // reserved sectors
   char fats;                 // number of FATs
   UINT root_dir_ents,        // number of root directory entries
        sectors;              // total sectors
   char media;                // media descriptor byte
   UINT fat_sectors,          // sectors per FAT
        sectors_per_track,    // sectors per track
        heads;                // number of heads
   long hidden_sectors,       // hidden sectors
        huge_sectors;         // sectors if above 32 Mb
};