Essential components There are typically four parts to a flash drive: Male type-A USB connector – provides a physical interface to the host computer.
USB mass storage controller – implements the USB host controller. The controller contains a small microcontroller with a small amount of on-chip ROM and RAM. NAND flashmemory chip – stores data. NAND flash is typically also used in digital cameras. Crystal oscillator– produces the device's main 12 MHz clock signal and controls the device's data output through a phase-locked loop.
Additional components The typical device may also include: Jumpersand test pins – for testing during the flash drive's manufacturing or loading code into the microprocessor. LEDs– indicate data transfers or data reads and writes. Write-protect switches – Enable or disable writing of data into memory.Unpopulated space – provides space to include a second memory chip. Having this second space allows the manufacturer to use a single printed circuit board for more than one storage size device. USB connector cover or cap – reduces the risk of damage, prevents the ingress of fluff or other contaminants, and improves overall device appearance.
Some flash drives use retractable USB connectors instead. Others have a swivel arrangement so that the connector can be protected without removing anything. Transport aid – the cap or the body often contains a hole suitable for connection to a key chain or lanyard. Connecting the cap, rather than the body, can allow the drive itself to be lost. Some drives offer expandable storage via an internal memory card slot, much like a memory card reader.
