Universal Serial Bus (USB)

A pen drive is a portable Universal Serial Bus (USB) flash memory device for storing and transferring

audio, video, and data files from a computer.

USB flash drives are typically removable and rewritable, and physically much smaller than

an optical disc.

• BEFORE PENDRIVE……...

FLOPPY DISC / DISKETTE,

1.44 megabytes

• COMPACT DISC

LIMITED STORING CAPACITY

SIZE

Optical discs require special drives to read/write.

Pua Khein Seng

First PEN DRIVE appeared in market in 1995 & 1998 with maximum transfer rate of 12mbps

High speed PEN DRIVES released in market in 2000 with speed of 480 mbps

Components involved

Standard-A USB plug.

controller chip is the ‘brain’ of the flash drive

NAND flash memory chip(s)

Crystal oscillator It is used as a digital “clock”.

Crystal Oscillator: It is used as a digital “clock”.

6)LED indicator light

3) The controller chip is the ‘brain’ of the flash drive.

2 ) NAND Flash memory storage chip is the place where all our files are stored.

Working mechanism:

• Pen Drives have a storage capacity up to 256 GB. The internal circuitry of the pen drive draws power from the computer for its operation

• There are two chips, one is the USB controller and the other is the flash memory chip.

• The IC SK6211 is a controller which facilitates the data communication between the PC/Laptop and the flash memory (EEPROM) of the pen drive

• The second chip is a NAND type flash memory which has fast read, write and erase cycles.

• The crystal oscillator used here runs at a clock frequency at 12 MHz

LATEST PENDRIVES

USES AND FEATURES………

MAJOR CONTRIBUTION IN MEMORY STORAGE…

EASY TO CARRY, PORTABLE ,FEASIBLE & DURABLE

RESISTANCE TO SCRATCHES AND DUST

Can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives

Pen drives are supported by operating systems such as Linux, OS X, Windows, Unix-like systems and read by many other systems such as the Xbox 360, PlayStation 3,

DISADVANTAGES

• SIZE : Being small leaves some devices to be easily misplaced

• IT BREAKS IT GONE : Compared to some CDs that can be repaired once scratched to retrieve data , USBs once they fail they fail .

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