In the external memory of the computer, a device similar to magnetic tape is used, which is called magnet disks. The circular magnetic disk is packed in a square sealed box to prevent scratches on the surface of magnetic disks, resulting in data loss.
Hard Disk: With magnet disks, people can use computers more conveniently. Not only can the results of data processing be stored in magnet disks, but also a lot of data input into the computer can be stored in magnet disks, so that these data can be used repeatedly, avoiding repeated work.
Magnet disks devices should include magnet disks drivers, adapters and disks, which can be used as input devices, output devices or carriers. Control floppy disk reading and writing, that is, input or output is completed by magnet disks driver and its adapter. Functionally speaking, a magnet disks device and a recorder function are the same. A tape can be recorded repeatedly, then floppy disk or hard disk, or information carrier, can also be changed repeatedly.
In traditional magnet disks management, a hard disk is divided into two categories: primary partition and extended partition. The main partition is a partition that can install the operating system and start the computer. Such partition can be formatted directly, then the system can be installed and the files can be stored directly. There are only four primary partitions on a hard disk. If more than four magnet disks
blocks are required on a hard disk, then extended partitions are required.
If extended partitions are used, there can be at most three primary partitions and one extended partition on a physical hard disk. Extended partitions cannot be used directly. They must be divided into one logical partition after a second partition before they can be used. Logical partitions in an extended partition can be arbitrary.