Introduction to the concept of USB key
A USB key (in English USB key) is a removable storage device of small format that can be plugged into the USB port of a computer.
A USB key embeds in a plastic shell a USB connector and flash memory, a semiconductor memory, non-volatile and rewritable, that is to say a memory having the characteristics of a RAM but whose data do not volatilize when the power is turned off.
Thus a USB key is capable of storing up to several gigabytes of data, while being able to retain the data when the power supply is cut off, that is to say when the key is unplugged.
In practice, a USB key is very practical for mobile users because it is very easy to transport and can contain a large amount of documents and data.
In addition, recent motherboards allow booting from USB keys, which means that it is now possible to start an operating system from a simple USB key! Convenient for users wishing to have their working environment wherever they are or to boot and troubleshoot a system in the event of a crash!
Features
The characteristics to take into account when choosing a USB key are as follows:
- Capacity
- Transfer rate : this is the data transfer speed. Note that the read transfer rate is usually different from the write transfer rate because the write process to flash memory is slower. The transfer rate depends on the read and write speed of the Flash memory, as well as the version of the USB standard supported: ** USB 1.1 (low speed USB) up to 12 Mbit / s,
- USB 2.0 (High speed USB or Hi-speed) up to 480 Mbit / s. It is important to note that to be able to take full advantage of this transfer rate, the key must be plugged into a USB 2.0 port. Otherwise (USB 1.1 port), the key will operate at low speed.
- Encryption features : some keys offer tools to encrypt the data or part of the data present on the key in order to strengthen their confidentiality.
- Write data protection : on some keys, a hardware switch allows the key to be read-only in order to avoid deleting or modifying data.
- Multimedia functions : when the USB key has a headphone socket and allows the playback of audio files (generally in MP3 format), we then speak of mp3 player ou mp3 player.
