biosPramBlock Struct Reference

Structure that defines a FAT16 volume. More...

#include <Fat16structs.h>

List of all members.

Public Attributes

uint16_t bytesPerSector
uint8_t sectorsPerCluster
uint16_t reservedSectorCount
uint8_t fatCount
uint16_t rootDirEntryCount
uint16_t totalSectors16
uint8_t mediaType
uint16_t sectorsPerFat16
uint16_t sectorsPerTrtack
uint16_t headCount
uint32_t hidddenSectors
uint32_t totalSectors32


Detailed Description

Structure that defines a FAT16 volume.

See FAT boot sector for entire block.


Member Data Documentation

Count of bytes per sector. This value may take on only the following values: 512, 1024, 2048 or 4096

Number of sectors per allocation unit. This value must be a power of 2 that is greater than 0. The legal values are 1, 2, 4, 8, 16, 32, 64, and 128.

Number of sectors before the first FAT. This value must not be zero.

The count of FAT data structures on the volume. This field should always contain the value 2 for any FAT volume of any type.

For FAT12 and FAT16 volumes, this field contains the count of 32-byte directory entries in the root directory. For FAT32 volumes, this field must be set to 0. For FAT12 and FAT16 volumes, this value should always specify a count that when multiplied by 32 results in a multiple of bytesPerSector. FAT16 volumes should use the value 512.

This field is the old 16-bit total count of sectors on the volume. This count includes the count of all sectors in all four regions of the volume. This field can be 0; if it is 0, then totalSectors32 must be non-zero. For FAT32 volumes, this field must be 0. For FAT12 and FAT16 volumes, this field contains the sector count, and totalSectors32 is 0 if the total sector count fits (is less than 0x10000).

This dates back to the old MS-DOS 1.x media determination and is no longer usually used for anything. 0xF8 is the standard value for fixed (non-removable) media. For removable media, 0xF0 is frequently used. Legal values are 0xF0 or 0xF8-0xFF.

This field is the FAT12/FAT16 16-bit count of sectors occupied by ONE FAT. On FAT32 volumes this field must be 0, and sectorsPerFat32 contains the FAT size count.

Sectors per track for interrupt 0x13. Not used otherwise.

Number of heads for interrupt 0x13. Not used otherwise.

Count of hidden sectors preceding the partition that contains this FAT volume. This field is generally only relevant for media visible on interrupt 0x13.

This field is the new 32-bit total count of sectors on the volume. This count includes the count of all sectors in all four regions of the volume. This field can be 0; if it is 0, then totalSectors16 must be non-zero.


The documentation for this struct was generated from the following file:

Generated on Thu Oct 9 08:22:19 2008 for Fat16 by  doxygen 1.5.6