These tapes are relatively cheap, but require expensive tape drives Quarter Inch 40MB - 5GB Quarter Inch Cartridges (QIC tapes) are relatively inexpensive and support fast data transfer rates, QIC mini cartridges are even less expensive, but their data capacities are smaller and their transfer rates are lower. 38 INFORMATION TECHNOLOGY TRAININGÄ¢ Type Capacity Description Half Inch 60MB 400MB Half inch tapes come both as 9 track reels and as cartridges. Tapes come in a variety of sizes and formats as given in Table Tapes are sometimes called streamers or streaming tapes. Tapes are also used for transporting large amounts of data. Data to be used regularly is almost always kept on a disk. Because tapes are so slow, they are generally used only for long term storage and backup. Accessing data on tapes, however, is much slower than accessing data on disks.
Tapes also have large storage capacities, ranging from a few hundred kilobytes to several gigabytes. Storing data on tapes is considerably cheaper than storing data on disks. Some computers, in fact, enable us to use normal cassette tapes. Tapes for computers are similar to the tapes used to store music. 4.2 MAGNETIC TAPE Magnetic tape is a magnetically coated strip of plastic on which data can be encoded.
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Other examples of direct access media are floppy diskettes, optical disks, zip disks, etc. In contrast, disks are random access also called direct access media because a disk drive can access any point at random without passing through intervening points. Magnetic tapes are examples of sequential access media. In the case of sequential access media, the data stored in the media can only be read in sequence and to get to a particular point on the media, we have to go through all the preceding points. Based on the type of access, they are called sequential access media or random media. This classification is based on the type of data access: sequential and random. There are two types of auxiliary storage devices. The most common types of auxiliary storage devices are magnetic tapes, magnetic disks, floppy disks, hard disks, etc. So even if by some accident the computer crashes and the stored data is unrecoverable, we can restore it from the back ups. They also function as back up devices which allow to back up the valuable information. Auxiliary storage devices are also useful in transferring data or programs from one computer to another.
Unlike RAM which loses the contents when the computer is turned off, and ROM, to which it is not possible to add anything new, auxiliary storage devices allow the computer to record information semi permanently, so it can be read later by the same computer or by another computer. The term non volatile means that stores and retains the programs and data even after the computer is switched off. This is a long term, non volatile memory.
4.1 AUXILIARY STORAGE DEVICES Auxiliary storage also known as auxiliary memory or secondary storage, is the memory that supplements the main storage. To understand other storage devices like CD-ROM, CD-R Drive etc. 1 C R4 H A P T E AUXILIARY STORAGE DEVICES LEARNING OBJECTIVES To discuss various To know about Magnetic Tape, Winchester Disk, Floppy Disk etc.