Simple in complex: hard disk drive

One of the main components of any computer is a hard disk. This device is also known under the slogan names "screw", "broom", "hard", "hard drive", "hard". The latter is due to the appearance of the English name - Hard Drive Disc (HDD), in the Russian language abbreviated to "hard". Winchester is a kind of data storage, the data on which, unlike RAM, are preserved even when the power is completely turned off. To a certain extent, the old video and audio cassettes in which the magnetic film performed the same function as the disks in hard disks can serve as an analogue.

There can be no doubt that many computer owners would like to know the hard drive device. What is there clicking inside when you turn on, why there is a chirping sound with active reading / writing information, etc. Yes, and on the case there are windows of an incomprehensible destination. There are many questions, but the hard drive is still a mystery.

This article we want to shed light on some key points. In addition, perhaps, an inquisitive user who has decided to start repairing the hard drives independently with the disassembly of the case, will think ten times about the expediency of this and turn to the service center.

The casing of all existing hard drives is made of metal. On the lower side there is a control electronics board. The chips can be soldered both from the outside (old models) and from the inside. This does not affect the performance, except that it is impossible to accidentally touch the protruding microchip at the internal location.

The hard disk device assumes the placement of a controller (MCU) on this board, a buffer memory chip (the usual DDR), a read / write head control module (VCM), a ROM memory with a control microprogram and a protective diode (TVS). The board is connected to the internal elements of the housing (hermetic) by copper pressure contacts.

Of course, the hard disk device can not be understood without removing (real or mental) the upper housing cover. Inside, on a single spindle of the electric motor (from 5,400 to 15,000 revolutions per minute, depending on the model), several disks of non-conductive material are placed. A magnetizable layer is deposited on their surface: let us recall the cassettes-the polymer tape was the basis there. Each disc is placed in a special aerodynamic arc, which forms the necessary air flow. The frame, at the ends of which the heads are placed, in the off state is fixed in a special parking area outside the surface of the discs with the aid of a latch and / or a magnet. After the spinning of the spindle, an air flow is created, the VCM card unlocks the frame and takes it to the working position. The heads do not touch the surface of the discs, but fly over them on an air cushion. By the way, when the power is turned off, the energy of rotation is enough to generate a current sufficient to lead the heads to the parking zone (about 20-30 years ago it was necessary to launch a high-level parking program).

Thus, there is no vacuum inside the hard drive, and "windows" in the housing are needed to equalize the pressure inside and out. Of course, the air inside is practically dust-free. Streaking with active use of the hard drive arises due to the frequent positioning of the heads on the desired part of the disk (track). But a quiet click at power-up can be caused by removing the parking zone lock or self-test frame.

By the way, the device of an external hard disk is exactly the same. Exception: the models that are gaining popularity on the basis of solid-state memory work on completely different principles.