PRESENTATION-Working of PEN DRIVE

Shudhanshu AgarwalB.tech (EC-2011)Roll no.-1101421102

CONTENTS

1) Introduction2) Structure of Pen Drive3) Technology Used4) Design & Implementation5) Essential Components6) Internal Structure (i) Controller (ii) Microchip 1 (iii) Microchip (iv) Oscillator7) Comparision8) Advantages & Disadvantages9) Conclusion

INTRODUCTION

A USB drive is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface

USB flash drives use the USB mass storage standard, supported natively by modern operating systems such as linux, Mac OS X, Windows, and other Unix-like systems, as well as many BIOS boot ROMs

USB drives with USB 2.0 support can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives.

They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts

The term drive persists because computers read and write flash drive data using the same system commands as for a mechanical disk drive.

A Kingston card reader which accepts Micro SD memory cards (Transcend card shown inserted) and acts as a USB flash drive, resulting in a size of approximately 2 cm in length, 1 cm in width and 2 mm in thickness

Punched cards in storage at a U.S. Federal records center in 1959. All the data visible here would fit on a 4 GB flash drive

STRUCTURE OF PEN DRIVE

A flash drive consists of a Printed circuit board USB connectorType-A USB connection Drives for other interfaces.

TECHNOLOGY USED Flash memory combines a number of older technologies The memory storage was based on earlier EPROM and

EEPROM technologies. Hardware designers later developed EEPROMs with the

erasure region broken up into smaller "fields" that could be erased individually without affecting the others.

The development of high-speed serial data interfaces such as USB and the simultaneous development of small, high-speed, low-power microprocessor systems allowed this to be incorporated into extremely compact systems.

Design and implementation

Internals of a typical USB flash drive

• 1 USB Standard-A plug • 2 USB mass storage controller

device • 3 Test points • 4 Flash memory chip • 5 Crystal oscillator • 6 LED• 7 Write-protect switch

(Optional) • 8 Space for second flash

memory chip

Essential componentsThere are typically four parts to a flash drive:Standard-A USB plug – provides a physical interface to

the host computer.USB mass storage controller – a small microcontroller

with a small amount of on-chip ROM and RAM.NAND flash memory chip(s) – 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.

The typical device may also include:

Jumpers LEDsWrite-protect switchesUnpopulated spaceUSB connector cover or capTransport aid.Some drives offer expandable storage via an internal

memory card slot, much like a memory card reader.[

LETS EXPLORE :-

USB Flash Drives or commonly called as Pen Drives arepopular removable storage media having a storage capacityfrom 64 MB to 32 GB. They are preferred over the other conventionalstorage devices like floppy disks or CD ROMs as they are faster, smaller and have a longer life span.

INTERNAL STRUCTURE

1.A printed circuit board carrying the circuit elements and a USB connector is shown in the above image.

2.The USB connector is protected by either retracting into the body or by covering by a removable lid. There are two chips, one is the USB controller and the other is the flash memory chip

CONTROLLER

The IC SK6211 shown in the above image is a controller which facilitates the data communication between the PC/Laptop and the flash memory (EEPROM) of the pen drive. It is fully compatible with USB 2.0 protocols and USB Mass storage class V1.0 specification. The devices like memory card, hard disk, pen drive etc with high data storage capacity fall under the category of Mass Storage Devices.

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MEMORY CHIP1

The chip which is shown in the image above is a NAND type flash memory which has fast read, write and erase cycles. The data is stored in memory cells of the EEPROM. The storage capacity of this memory is 2GB. There is another similar chip with storage capacity of 2GB on the other side of the PCB, thereby making the total capacity of the pen drive to be 4GB.

MEMORY CHIP

The above image shows the other side of PCB. The second memory chip, a crystal oscillator and a number of surface mount components are soldered which are required for the operation of the pen drive.

OSCILLATOR

The crystal oscillator produces the clock signal for the correct operation of the device. The crystal oscillator used here runs at a clock frequency at 12 MHz.

COMPARISON WITHTapeMagnetic Tapes stores data sequentially, hence sequential accessing of data is

possible only, whereas in USB flash drive random accessing can be done.

Floppy diskSize of pen-drive is much smaller than floppy Disk(3.5 inch).Not used in modern computers.

Optical media RW varieties up to about 1,000 erase/write cycles, while modern NAND-based flash drives often last for 500,000 or more erase/write cycles. They are slower than their flash-based counterparts Standard 12 cm optical discs are larger than flash drives and more subject

to damage.

ADVANTAGES Flash drives use little power, have no fragile

moving parts, and for most capacities are small and light.

Data stored on flash drives is impervious to mechanical shock, magnetic fields, scratches and dust.

Specially manufactured flash drives are available that have a tough rubber or metal casing designed to be waterproof and virtually "unbreakable". These flash drives retain their memory after being submerged in water, and even through a machine wash.

DISADVANTAGESFlash drives can sustain only a limited number of write and erase cycles before the drive fails.

USB flash drives are more expensive per unit of storage than large hard drives, but are less expensive in capacities of a few tens of gigabytes as of 2011.

Thank

You………