The Universal Serial Bus (USB) is a bus standard for inexpensively connecting external peripheral devices to a personal computer. It does not require rebooting of the host computer when a peripheral device is connected to the host computer and ensures fast transmission rate. Presently, USB provides an expandable, hot-pluggable serial interface that ensures a standard, low-cost connection for peripheral devices such as keyboards, mice, joysticks, printers, scanners, storage devices, modems, and the like. The USB interface possesses a variety of advantages, such as fast data transmission speed, simple and quick connection, plug-and-play (PnP) compatibility, lack of an external power-supply, ability to simultaneously support a plurality of devices, excellent compatibility, and so forth, making USB a standard for connecting equipment to personal computers. Universal-Serial-Bus (USB) has become a popular standard interface for connecting peripherals to a host such as a personal computer. USB-based flash-memory storage devices or drives have been developed to transport data from one host to another, replacing floppy disks. While large external flash drives may be used, smaller USB flash drives known as key-chain or key drives have been a rapidly growing market. In general, the USB flash drive is a small memory storage apparatus that interfaces with a host system through a USB connector. The apparatus uses low power non-volatile flash memory as its storage media instead of conventional rotating hard disk media. More recently, flash memory cards are being sold that contain a USB connector. Such USB-flash memory cards do not require a specialized reader but can be plugged into a USB connector on a personal computer (PC) or other hosting device. These USB-flash memory cards can be used in place of floppy disks. A USB-flash card can have a capacity of more than ten floppy disks in an area not much larger than a large postage stamp.

Flash memory is a type of nonvolatile rewritable memory useful in a wide variety of digital data applications that require occasional writing and/or rewriting of data, nonvolatile storage, and relatively high-speed read capability. A flash memory array is constructed of a large plurality of floating-gate metal-oxide-silicon field effect transistor devices arranged as memory cells in typical row and column fashion with circuitry for accessing individual cells and placing the memory transistors of those cells in different memory conditions. Such memory transistors may be programmed by storing a charge on the floating gate. This charge remains when power is removed from the array. Flash memory has gained wide acceptance for its non-volatile storage, which is ideal for portable devices that may lose power, since the data is not lost when stored in the flash memory. A wide variety of removable storage media exists for transferring data from one computing device to another computing device or to a portable, consumer electronic device. The removable storage media allows users to easily transport data between various devices and various computers. One of the most popular types of removable storage media is the flash memory card, which is compact, easy to use, and has no moving parts. A flash memory card is a memory card involving one or more silicon chips, and it is often referred as a portable memory card. A flash memory card includes an internal, high-speed solid-state memory capable of persistently storing data without application of power. Because flash memory cards are small, power saving, large in volume, shock resistant, and rewritable, they have been widely used in information appliances and various portable digital products, such as PDAs, MP3 Players, etc. Flash card readers are sometimes used to transfer digital data, such as digital picture files, from the removable flash card to a PC. The flash-memory card can be removed from the digital camera and inserted into a slot on the flash-card reader. The user can then copy the digital-picture files to the PC using the flash-card reader. A wide variety of flash memory cards have been recently introduced, each having different capacities, access speeds, formats, interfaces, and connectors. Examples of memory cards include CompactFlash, the Memory Stick, Smart Media, Secure Digital (SD) memory cards, and MultiMedia Cards (MMCs).

A flash memory drive is a device that is used to access flash memory cards. A USB flash drive can be constructed from a microcontroller, a flash-memory controller or interface, and one or more flash-memory chips. A serial interface on the microcontroller connects to the USB bus to the host, and data from the serial interface is transferred through the microcontroller to the flash controller and is written to the flash-memory chips. The microcontroller can drive an output port that connects externally to a LED. The microcontroller can then turn the LED on or off by writing a zero or a one to the output port. A conventional flash memory drive typically is a small plastic or metal case-shape device that can be embedded in or externally connected to a computer system or a portable digital product through its signal transmission unit. There is an opening on the leading edge of the flash memory drive to enable a memory card to be inserted in the flash memory drive. When a memory card is inserted in said flash memory drive through the opening, it will be connected to the computer system or portable digital product via the signal transmission unit of the flash memory drive), and the computer or digital product can access the memory card with the help of the flash memory drive.