The magneto-optical (MO) drive is a popular way to back up files on a personal computer. As the term implies, an MO device employs both magnetic and optical technologies to obtain ultra-high data density. A typical MO cartridge is slightly larger than a conventional 3.5-inch magnetic diskette, and looks similar. But while the older type of magnetic diskette can store 1.44 megabytes (MB) of data, an MO diskette can store many times that amount, ranging from 100 MB up to several gigabytes (GB).
An MO system achieves its high data density by using a laser and a magnetic read/write head in combination. Both the laser and the magnet are used to write data onto the diskette. The laser heats up the diskette surface so it can be easily magnetized, and also to allow the region of magnetization to be precisely located and confined. A less intense laser is used to read data from the diskette. Data can be erased and/or overwritten an unlimited number of times, as with a conventional3.5-inch diskette.
Examples of magneto-optical drives are the Fujitsu DynaMO, a 230 MB drive used in the PowerPC Apple Powerbook, a note book computer, and the Pinnacle Micro Vertex, a 2.6 GB drive.
The chief assets of MO drives include convenience, modest cost, reliability, and (for some models)widespread availability approaching industry standardization.The chief limitation of MO drives is that they are slower than hard disk drives, although they are usually faster than conventional 3.5-inch diskette drives.