Storage Media

Primary storage includes RAM and ROM. Random-access memory or ROM is the part of memory that is used for storing programs and data. RAM is the part of memory that can be accessed or altered as needed by each program. It depends on a steady supply of electricity to maintain data storage. When the power to the computer is shut off, everything stored in RAM is lost. In other words, RAM is volatile.

Read-only memory or ROM contains prewired functions. It cannot be altered by programmed instructions. Several types of ROM can be programmed according to the user’s specifications. Programmable read-only memory (PROM) allows a chip to be programmed only once. Erasable programmable read-only memory (EPROM) can be reprogrammed. Electrically erasable programmable read-only memory (EEPROM) can be erased and reprogrammed electrically so there is no need to remove it from the circuit as with an EPROM.

In some applications, a computer’s primary storage capabilities are insufficient to handle the instructions and data needed for processing. A limitation of primary storage is its volatility. Hence, supplemental storage is necessary. The solution to these limitations is found in the use of secondary storage.

Secondary storage is the non-volatile memory that is stored externally to the computer. Three secondary-storage media are: magnetic tapes, magnetic disks and optical technology.

A magnetic tape is a high-speed device that, like a home tape recorder, can read data from a magnetic tape and can also record data onto a tape. The tape itself, is a file type that can serve as input to a computer or as output from a computer. It is one of the most common file types for storing high-volume data that is typically processed in a batch mode.

It is a one-half or one-fourth inch ribbon of mylar (a plastic-like material), coated with a thin layer of iron-oxide material. Tapes can store large quantities of data inexpensively and are often used as backup storage media. They are erasable, reusable and durable. However, magnetic tapes are not suited for data files that are revised or updated often. These files should be stored on a medium where access to data is faster and more direct.

A magnetic disk is a mylar or metallic platter on which electronic data can be stored. Although disks resemble phonograph records, they do not have characteristic spiral groove; however, data are accessed in much the same way as an individual song is selected on a record.

Magnetic disks has several advantages over magnetic tapes, such as, the ability of magnetic disks to access the data directly, the ability to hold more data in a smaller space, and the ability to attain faster data transfer speeds.

Magnetic disks are manufactured in both floppy diskette and hard disk styles.

A floppy disk is a small flexible mylar disk on which data are stored. Today it is available in three sizes—the 31/2 inch microfloppy, as well as 51/ 4inch size and 8 inch size. They are not of much use these days.

A hard disk, as its name tells, is hard and inflexible. The device used to transfer data to and from a hard disk is a hard-disk drive. Because of its hard construction, the hard disk allows data to be stored more densely. They are available for all sizes of computers. They may be permanently installed in a drive or may be in the form of a removable cartridge or disk pack that can also be removed from the drive.

When it comes to supplemental data storage, nothing has quite revolutionized portability like optical storage devices. Optical technology involves the use of laser beam. It has created new types of storage media. CDs, DVDs and Blue-Ray are all optical disks. Optical disks can be read-only, and the more expensive ones can be written on and erased. While not suited to applications where data changes, these disks are very convenient for storing data that remains constant.

Another popular storage media includes USB flash drives, which is a solid state memory. It is chip-based and fast. It can store some gigabytes of information. It is ideal for portable storage and back-up of files.

A Computer Guy

Storage Media