The internal operation and technology of storage devices
Introduction
There are three main tpyes of technology for storage. These are solid state, magnetic and optical.
Solid state devices (Flash devices)
Solid state devices have no moving parts. That means they can't get worn out and are not quite as easily damaged by bangs and knocks as optical and magnetic devices. They store store data in binary patterns using billions of tiny switches. Another point to note about solid state devices is that they need very little power to work and can get the power that they do need from the device that they are plugged into. Examples include, SD cards, micro SD cards and pen drives. Many computers and laptops are now being sold with solid state hard drives. Although typically much smaller (and cheaper) than magnetic hard drives, they are so much faster! A solid state hard drive can breathe new life into an old laptop.
Magnetic devices
These store binary data patterns as billions of magnetised areas on a disk. These areas can be read from or written to by a special head that moves over the magnetic area. With hard disk drives and floppy disk drives, the disk spins very quickly (thousands of times a second) whilst the head moves over the magnestised areas, reading from and writing data to the disk. One of the things to look out for if you ever have to buy a new hard drive is how fast the disk or disks spin (hard disks often have more than one disk inside them) - the faster they spin, the quick reading and writing data can take place so the faster your computer can work.
Optical devices
Optical devices store binary patterns using lasers. The lasers shine onto a disk and change whether an area on it can reflect light or not. The laser can then be used to read back patterns by shining a laser on the disk and looking at which areas reflect light and which don't. Some types of disk can be written to just once, although you can read from them many times. These are known as 'WORM' storage devices (Write Once Read Many). CD-ROMs, DVDs and Blu-ray disks are examples of WORM disks. They are often used by manufacturers to distribute software. Other media, such as CD R/W can be written to many times as well as read many times.