Computer memory devices

Main characteristics of hard drives:

• Interface - the method used to transfer data (IDE or ATA, Serial ATA, SCSI ...).
• Capacity - the amount of data that can be stored by the drive. The capacity of modern devices reaches 1000 GB.
• Physical size (form factor) - Almost all modern drives for personal computers and servers are either 3.5 or 2.5 inches in size. The latter are more commonly used in laptops.
• Random access time.
• Spindle speed.
• Reliability.
• Noise level ... etc.

The hard drive is a fragile device

• Malfunctions occur during computer operation. Viruses, power outages, software errors - all of these can damage the information stored on your hard drive. Damage to information does not always mean its loss, so it is useful to know how it is stored on the hard disk, because then it can be restored. Then, for example, in the event of a virus damaging the boot area, it is not at all necessary to format the entire disk (!), But, having restored the damaged space, continue normal work with preserving all your invaluable data.
• Rather fragile and miniature elements are used in hard drives. To preserve the information and functionality of hard drives, it is necessary to protect them from impacts and sudden changes in spatial orientation during operation.

Laser discs and drives

• Laser drives use the optical principle of reading information.
• On laser discs CD (CD - Compact Disk, compact disc) and DVD (DVD - Digital Video Disk, digital video disc) information is recorded on one spiral track (like on a gramophone record), containing alternating areas with different reflectivity. The laser beam hits the surface of the rotating disk, and the intensity of the reflected beam depends on the reflectivity of the track section and becomes 0 or 1.

Blu-ray Disc - the next generation of optical format

• Blu-ray Disc or BD for short (from English blue ray - blue ray and disc - disc) is the next generation of optical disc format - used for storing digital data, including high-definition video with increased density.
• Blu-ray (literally "blue-ray") gets its name from a shortwave 405 nm "blue" (technically blue-violet) laser that can write and read much more data than DVD, which has the same physical volume. but uses a longer wavelength red laser (650 nm) for recording and reproduction. A single layer Blu-ray Disc (BD) can store up to 27GB of information.
• Blu-ray uses an experimental security element called BD + that allows you to dynamically change the encryption scheme.

Flash memory devices

• Flash memory is a non-volatile type of memory that allows you to write and store data on microcircuits. Flash-based devices have no moving parts, which ensures high data security when used in mobile devices.
• The flash memory was discovered by Fuji Masuoka when he worked at Toshiba in 1984.
• Recently, devices based on flash memory (flash cards, flash drives) have replaced floppy disks.
• USB Flash Drive (flash drive or flash drive) is a storage medium that is connected to a computer or other reading device via a standard USB connector.

File

• Information on external media has a file organization.
• A file is information that is stored on an external medium and has its own name.
• The disks also have a directory (reference book, index) of the disk containing the names of the stored files, their sizes, creation time, etc.