Raw capacity is a characteristic of a computer storage and is the total amount of stored information that a storage device or medium can hold. It is expressed as a quantity of bits or bytes (e.g. 10.4 megabytes).
Example of Maximum disk capacity
In 1998, with a 24 bit address mode and because all hard disks are low-level formatted with a standard 512-byte sector, the maximum disk capacity described by the partition table is calculated as follows:
Maximum capacity = sector size x cylinders (10 bits) x heads (8 bits) x sectors per track (6 bits)
Using the maximum possible values yields:
512 x 1024 x 256 x 63 (or 512 x 2^24) = 8,455,716,864 bytes or 7.8 GB
|Year||Cylinders||Head||Sectors per track||Total per byte||Sector size||Maximum Capacity|
|Address Byte||1998||10||8||6||24||512||7.8 GB|
| Maximum capacity |
per byte (2^n)
|1998||1024||256||63||15,75 MB||512||7.8 GB|
The calculation results in a maximum capacity of slightly less than 8 gigabytes (GB). Before BIOS INT 13h extensions drive geometry translation (also known as logical block addressing (LBA) were introduced in 1998, the active, primary partition could not exceed 7.8 GB, regardless of the file system used.
Since Hard drives over:
- 137.4 GB are supposed to report an LBA capacity of 0xfffffff = 268435455 sectors (137438952960 bytes).
- Now the actual disk size is found in the new 48-capacity field.
Maximum capacity by Byte