tYpE oF PeNdRiVe

HiStOrY

First commercial product

Trek Technology and IBM began selling the first USB flash drives commercially in 2000. Trek Technology sold a model under the brand name "ThumbDrive", and IBM marketed the first such drives in North America with its product named the "DiskOnKey," which was developed and manufactured by M-Systems.[20] IBM's USB flash drive became available on December 15, 2000,[21] and had a storage capacity of 8 MB, more than five times the capacity of the then-common floppy disks.

In 2000, Lexar introduced a Compact Flash (CF) card with a USB connection, and a companion card read/writer and USB cable that eliminated the need for a USB hub.[citation needed]
Second generation

Modern flash drives have USB 2.0 connectivity. However, they do not currently use the full 480 Mbit/s (60 MB/s) which the USB 2.0 Hi-Speed specification supports because of technical limitations inherent in NAND flash and the overhead required for USB data transfers (8-bit / 10-bit encoding and protocol)[22]. The fastest drives currently available use a dual channel controller, although they still fall considerably short of the transfer rate possible from a current generation hard disk, or the maximum high speed USB throughput.

File transfer speeds vary considerably. Speeds may be given in Mbyte per second, Mbit per second or optical drive multipliers such as "180X" (180 times 150 KiB per second). Typical fast drives claim to read at up to 30 megabytes/s (MB/s) and write at about half that speed. This is about 20 times faster than USB 1.1 "full speed" devices, which are limited to a maximum speed of 12 Mbit/s (1 MB/s with overhead)[23].
Third generation

Like USB 2.0 before it, USB 3.0 offers dramatically improved data transfer rates compared to its predecessor. USB 3.0 was announced in late 2008, but consumer devices were not available until the beginning of 2010. The USB 3.0 interface specifies transfer rates up to 5 Gbit/s (625 MB/s), compared to USB 2.0's 480 Mbit/s (60 MB/s). All USB 3.0 devices are backward compatible with USB 2.0 ports. Computers with USB 3.0 ports are becoming very popular and common. Many newer laptops and desktops have at least one such port. USB 3.0 port expansion cards are available to upgrade older systems, and many newer motherboards feature two or more USB 3.0 jacks. Even though the USB 3.0 interface allows extremely high data transfer speeds, as of 2011 most USB 3.0 flash drives do not utilize the full speed of the USB 3.0 interface due to limitations of their memory controllers (though some four channel memory controllers are now coming to market)..