Pen drives: .
Pen Drive is a type of Universal Serial Cable (USB) flash drive. It is a kind of memory card that can be plugged into a computer’s USB port. It is termed “Pen drive” with reference to its size. It is small and compact thus making it fit into the palm of our hand. It is often flat and rectangular like a highlighter pen. A pen drive is used to store data and has a storage capacity of 64 MB to 64 GB.
The concept involved in the pen drive is that the memory is stored in the form of the array where in the information or the data is stored. The information or the data is stored in the form of the array of transistors. This array of transistors is called as the cells. Each of these cells stores at least one bit of information traditionally. But due to the advancements in the technology the newer versions may even have multi level cells. The data can be stored in more than a bit or specifically only one bit per cell. This is done by the technique of varying the number of electrons that are placed over the floating gate of the cell. The concept of the flash memory is based on the principle of the Floating Gate Avalanche Injection Metal Oxide Semiconductor or in short referred to as the FAMOS transistor. This is the NMOS transistor. This transistor has an additional conductor that is suspended in between the source/drain terminals and gate. The flash memory comes usually in two types. These is two types are mentioned below: the first one is the NOR flash and the second one being the NAND flash. The names given to the types of the flash memory actually refer to the type of the logic gate that is used in each storage cell.
The flash memory that is used in the pen drive is actually a non volatile memory that is the contents remain intact even if there is a power failure. Pen drive has a flash memory and the type of memory is EEPROM (Electrically Erasable Programmable Read Only Memory).
The above diagram shows the tear down of a HP V165W 8 GB pen drive.
Internals of an USB disk 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. Wire protect switch(Optional)
8. Space for second memory chip
Advantages of Pen drive over other storage devices .
The greatest advantage of a pen drive is its size and portability. The small size of the pen drive and the amount of data that can be accommodated in a pen drive are not comparable to any other storage device. Moreover, the speed of data transfer to or from the pen drive is very high. Pen drives are not affected by dust, water and fungus, which is the case with many floppy disks. The power consumption of pen drives is also very less. Almost all the operating systems support and detect pen drives. Also, you can protect the data on your pen drive by making it password protected. Nowadays, mp3 players and digital camera are included in the pen drives. Pen drives are available in a wide variety of storage capacities and are available at affordable prices.
Pen drives are being increasingly used as a data storage device due to their versatile features. With the advancing technology, the storage size and the data transfer speed are also increasing day by day.
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