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. As long as the desktop or laptop has a USB port, and the pen drive is compatible with the operating system, it should be easy to move the data from the hard drive to the device — and to another computer — in a matter of minutes. The drive gets its name from the fact that many have a retractable port connector like a ballpoint pen, and they are small enough to fit into a pocket. Other names include flash drive, jump drive, and thumb drive.
How to Use It
Using a pen drive is simple: the user inserts one end of the drive, which is equipped with a USB connector, into the USB port on a desktop or laptop and activates it. Once the drive is active, files can be dragged and dropped or copied and pasted into the memory. The process is usually no more difficult than attaching files to an email or copying files onto a disk, mp3 player, or other storage device.
There are several different computer operating systems in use today, so most manufacturers configure their pen drives to work with a variety of systems. Before buying any portable storage device, a consumer should read the packaging carefully to make sure that it will work with his or her computer system. Frequently, even users who own older operating systems can find compatible storage devices, as long as those computers have a USB port.
How It Works
Technicians classify pen drives as NOT AND, also called NAND, gate-style data storage devices. This technology works by storing data in blocks rather than randomly; as such, it doesn't work in the same way that a computer's main memory systems — read-only memory (ROM) and random-access memory (RAM) — do. Using blocks rather than allowing random access allows the drive to store more information and be made at a lower cost.
The actual transfer speed depends upon several factors, such as the computer's speed at reading and writing to the device. Generally, a pen drive's advertised speed is the reading speed because it is faster than the speed at which data can be written to it. Manufacturers usually list the speed in megabytes per second (MB/s). The age of the drive and how it's being used — such as for writing and erasing small files — also affects the transfer speed.
Equipped with a large amount of memory, the pen drive is often considered to be an improvement on both the older floppy drive disks and the more modern compact disks. They can transfer data much more quickly than these older technologies. Because they are solid state — there are no moving parts — flash drives usually last longer and the data stored on them is safer. Depending on the storage size, flash drives can hold anywhere from 128 MB to 32 GB or more; by comparison, a standard CD-ROM holds about 700 MB of data.
Even a pen drive with a relatively low storage capacity tends to provide plenty of space for all different types of files. Any file that can be stored on a computer's hard drive can usually be copied to a flash drive, as long as there is enough memory. There are also programs that can be run directly from the drive, without needing to be installed on the computer first.
Pen drives do have a few limitations, including how many times they can be used. Each drive has a limited number of program-erase cycles (P/E cycles), which is the act of putting files onto the drive and erasing them. Typically, the device can go through 100,000 P/E cycles before the integrity of the unit is compromised and files become corrupted.
Another limitation concerns the way manufacturers build the devices. The NAND gate-style allows a user to program or read the data one byte or word at a time, but erases data in blocks. When only small amounts are erased, the storage capacity is reduced.
The NAND gate-style device also may cause the loss of data because of the way that the information is accessed. Reading data in one cell may trigger changes in the cells that surround it. Generally, a user must read the cell thousands of times before this occurs, however, and rewriting the surrounding cells periodically may prevent this problem.
The computer chip in the drive can also wear out, causing the device to operate more slowly. The NAND gate-style method of programming and erasing files that are smaller than a block can also slow things down. This can make the device mark some blocks as bad, even though they are not completely full; trying to read bad blocks and remapping them can reduce the speed with which the device functions.