24-11-2012, 05:21 PM
Secondary Storage Devices
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Secondary Storage Devices : Introduction
Secondary storage (also known as external memory or auxiliary storage), differs from primary storage in that it is not directly accessible by the CPU.
The computer usually uses its input/ output channels to access secondary storage and transfers the desired data using intermediate area in primary storage.
Secondary storage does not lose the data when the device is powered down—it is non-volatile.
Classification Of Secondary Storage Devices
Two major types of secondary storage devices:
Direct Access Storage Devices (DASDs)
Magnetic Discs Hard disks (high capacity, low cost, fast) Floppy disks (low capacity, lower cost, slow)
Optical Disks CD-ROM = (Compact disc, read-only memory
Serial Devices
Magnetic tapes (very fast sequential access)
Hard Disk Drive
A hard disk drive is a device for storing and retrieving digital information, primarily computer data.
It consists of one or more rigid (hence "hard") rapidly rotating discs (platters) coated with magnetic material, and with magnetic heads arranged to write data to the surfaces and read it from them.
Hard drives are classified as non-volatile, random-access, digital, magnetic, data storage devices.
Introduced by IBM in 1956, hard disk drives have been the dominant device for secondary storage of data in general purpose computers since the early 1960s.
Zip Drive
A Zip drive is a small, portable disk drive used primarily for backing up and archiving personal computer files.
The trademarked Zip drive was developed and is sold by Iomega Corporation.
Zip drives and disks come in two sizes. The 100 megabyte size actually holds 100,431,872 bytes of data or the equivalent of 70 floppy diskettes.
There is also a 250 megabyte drive and disk.
Floppy Disk
A soft magnetic disk; It is called floppy because it flops if you wave it (at least, the 5.25-inch variety does). Unlike most hard disks, floppy disks (often called floppies or diskettes) are portable, because you can remove them from a disk drive.
Disk drives for floppy disks are called floppy drives.
Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive. And most importantly, they are portable.
Floppies come in three basic sizes:
[attachment=41063]
Secondary Storage Devices : Introduction
Secondary storage (also known as external memory or auxiliary storage), differs from primary storage in that it is not directly accessible by the CPU.
The computer usually uses its input/ output channels to access secondary storage and transfers the desired data using intermediate area in primary storage.
Secondary storage does not lose the data when the device is powered down—it is non-volatile.
Classification Of Secondary Storage Devices
Two major types of secondary storage devices:
Direct Access Storage Devices (DASDs)
Magnetic Discs Hard disks (high capacity, low cost, fast) Floppy disks (low capacity, lower cost, slow)
Optical Disks CD-ROM = (Compact disc, read-only memory
Serial Devices
Magnetic tapes (very fast sequential access)
Hard Disk Drive
A hard disk drive is a device for storing and retrieving digital information, primarily computer data.
It consists of one or more rigid (hence "hard") rapidly rotating discs (platters) coated with magnetic material, and with magnetic heads arranged to write data to the surfaces and read it from them.
Hard drives are classified as non-volatile, random-access, digital, magnetic, data storage devices.
Introduced by IBM in 1956, hard disk drives have been the dominant device for secondary storage of data in general purpose computers since the early 1960s.
Zip Drive
A Zip drive is a small, portable disk drive used primarily for backing up and archiving personal computer files.
The trademarked Zip drive was developed and is sold by Iomega Corporation.
Zip drives and disks come in two sizes. The 100 megabyte size actually holds 100,431,872 bytes of data or the equivalent of 70 floppy diskettes.
There is also a 250 megabyte drive and disk.
Floppy Disk
A soft magnetic disk; It is called floppy because it flops if you wave it (at least, the 5.25-inch variety does). Unlike most hard disks, floppy disks (often called floppies or diskettes) are portable, because you can remove them from a disk drive.
Disk drives for floppy disks are called floppy drives.
Floppy disks are slower to access than hard disks and have less storage capacity, but they are much less expensive. And most importantly, they are portable.
Floppies come in three basic sizes: