What is a hard drive in a personal computer?

Probably, there is no such computer owner who would not want to learn about what a Winchester is. Some of idle curiosity, others - because of the need. It should be recognized that with the regular use of computer technology, among all the components, the hard drive is the first applicant for a "take-off". This is explained quite simply: in an average computer this device is the only one in the design of which mobile parts are used (fans and CD-ROM drives can be ignored).

Let's try to understand what a Winchester is and what it's for. With a device installed in almost every computer, you need to be familiar. According to the generally accepted definition, a hard drive (hard drive, hard drive, screw, HDD) is an information storage device based on the principle of magnetizing a metal surface by an electromagnetic field. To understand what is at issue, it is enough to recall audio and video cassettes, so popular in due time. In them, the recording head magnetized the tape with a magnetic layer (iron oxide or chromium oxide ) in a special way. Of course, this comparison gives only a remote idea of what a Winchester is, especially since only the principle remained in the screws from the cassettes. In order to understand the issue in more detail, we will make a mental journey inside the classic computer hard drive.

A small rectangular metal box, to which two wires (an interface cable from the motherboard and power from the unit) are connected - this is our goal. On the outside, there may be holes, pasted with stickers with threatening inscriptions about their peeling off. These holes are needed to equalize the pressure inside and outside the housing, which allows for compensation of differences (necessary for operation). Inside there are several glass or aluminum disks, on both surfaces of which a layer of chromium dioxide is sprayed.

Disks (plates, pancakes) are fixed on a common spindle rotated by a constant speed motor (5400, 7200, 1000 rpm). This is the first constructive element. The second is the head block. A special frame, capable of moving between the plates in accordance with the commands of the controller, contains a number of magnetic heads. When the power is supplied, the disks are untwisted, there is a flow of air, due to which the heads "fly" over their surfaces at a distance of about 10 nm (there is no direct contact, as in the cassettes). If the power is interrupted, the frame by the stepping motor is removed from the zone of the discs to prevent contact and is parked (fixed by a magnetic latch). The frame can be moved thanks to a residual charge of capacitors, which is sufficient to power the stepper motor.

Of course, this is a very simplified scheme, giving only a general idea of what a Winchester is. More information can be found on the web.

As already mentioned, the hard drive is one of the most used components. The operating system, applications and all user files are written to it. Recently, devices have appeared, based on a completely different principle. These are solid state drives or SSDs. Since there are no moving parts in them, the speed of operation (often) exceeds the classical HDD. However, until they can not be recommended as a complete replacement for "screws" with magnetic disks, as the cost is much higher, and the reliability is less (the number of read / write cycles is limited). By the way, there is nothing revolutionary in SSD disks - this is the same flash memory technology that every USB flash drive owner faces.