What is a disk

A disk is an external storage device in a computer used to store and retrieve data. It consists of one or more magnetic platters, each of which is divided into one or more tracks and sectors. Data is read and written by rotating the platter and moving the heads. It has the characteristics of high capacity, high durability and reliability, and is widely used in computer systems.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

A disk is an external storage device in a computer that is used to store and retrieve data. It consists of one or more magnetic platters, each of which is divided into one or more tracks and sectors. Disks read and write data by rotating the platters and moving the heads.

The working principle of magnetic disks is based on the properties of magnetic materials. The disk surface is coated with magnetic material, and by applying a magnetic field to the magnetic material, the magnetic properties of the magnetic material can be changed to store and retrieve data. The data on the disk is stored in binary form, with each bit corresponding to a state of the magnetic material, such as 0 or 1.

The reading process of a disk involves the movement of the magnetic head and the rotation of the platter. When the computer needs to read data, the magnetic head will move to the specified track and then wait for the area to rotate to the position of the magnetic head. Once the sector is in place, the head reads or writes the data. This process is very fast because the disk rotates at a high speed (usually several thousand revolutions per minute).

The capacity of a disk depends on several factors, including the number of platters, the number of tracks and sectors per platter, and the storage capacity of each sector. With the advancement of technology, the capacity of disks has gradually increased, from the first few megabytes to the current tens or hundreds of megabytes, or even larger.

Disks are widely used in computer systems to store operating systems, applications, files and other data. It has very high data durability and reliability, and the data on the disk can remain unchanged even if the computer is powered off. This is because the data on the disk is stored through the state of the magnetic material, without the need for current to maintain it.

In addition to the traditional mechanical hard drive (HDD), there is also a new type of disk called a solid-state drive (SSD). SSD uses flash memory chips rather than magnetic materials to store data. Compared with mechanical hard drives, SSDs have faster reading and writing speeds, lower energy consumption, and smaller sizes. However, SSDs have higher cost, smaller capacity, and limited lifespan. Therefore, in current computer systems, mechanical hard drives and solid-state drives are often used in combination to strike a balance between performance and cost.

In summary, an external storage device in a disk computer reads and writes data by rotating the platter and moving the magnetic head. It has the characteristics of high capacity, high durability and reliability, and is widely used in computer systems. With the advancement of technology, the capacity and performance of disks continue to improve, providing computer users with a better data storage and access experience

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