USB Flash Drives or commonly called as Pen Drives are popular removable storage media having a storage capacity up to 256 GB. They are preferred over the other conventional storage devices like floppy disks or CD ROMs as they are faster, smaller and have a longer life span. The internal circuitry of the pen drive draws power from the computer for its operation. They have an integrated USB interface to communicate with the computer. The important parts of the pen drive are USB connector, crystal oscillator, memory chips and a controller to interact with the PC. The pen drive used here has storage capacity of 4GB.
Floppy disk, another interesting invention of the computer age is a storage device used to store and carry data. Although obsolete now a days, it has been replaced by technologically superior storage media like CD, DVD, Pen drive, portable hard disc etc. Historically this technology was dominant in the markets for more than two decades. Floppy disks are commonly identified by their sizes. The 3.5 inch disk with a maximum capacity of 1.44MB was the most commonly used floppy. The data inside a floppy is magnetically stored on a thin plastic sheet which is coated with iron oxide. It is commonly called as magnetic disk.
The Secure Digital (SD) Card or more commonly known as memory cards are small size storage devices that are specially designed to store and transfer data from audio and video consumer electronic devices like digicam, cell phones, voice recorders etc. They are known as secure digital card because they include a copyright protection mechanism that complies with the security of the SDMI (Secure Digital Music Initiative) standards. In this mechanism, a mutual authentication and encryptions are used to protect the card content from illegal usage. The notch in the tip right corner of the card helps to identify the right way of attaching with the device. As per the standards, each SD card is formatted with a File Allocation Table (FAT) file system, which allows every operating system to access the files in that system.