#Disk geometry calculator code#

Therefore, the maximum size for a FAT volume is 4 GB. However, the maximum cluster size that you can use for FAT volumes when running Windows NT is 64K, when using a 512 byte sector size. The maximum formatted capacity is slightly less than 8 GB. Substituting the maximum possible values yields:ĥ12 x 63 x 1024 x 256 = 8,455,716,864 bytes or 7.8 GB MaxCapacity = (sector size) x (sectors per track) x (cylinders) x (heads) Since current hard disks are low-level formatted with the industry standard 512-byte sector size, the maximum capacity disk that can be described by the Partition Table can be calculated as follows: However, sectors start counting at 1 (versus 0 for the other fields), so the maximum number of sectors per track is 63. The Starting and Ending Sector field is 6 bits long, limiting its range to 0 – 63. The Starting and Ending Head fields are one byte long, which limits this field to the range 0 – 255. The Ending Cylinder field in the Partition Table is ten bits long, which limits the maximum number of cylinders that can be described in the Partition Table to 1024.

#Disk geometry calculator code#

The code in the Master Boot Record uses these fields to find and load the Partition Boot Sector. On x86-based computers, the Starting and Ending Head, Cylinder, and Sector fields on the startup disk are very important for starting up the computer.

Contents Starting and Ending Head, Sector, and Cylinder Fields