Page 41 - gyamfi series vol. 2

INFORMATION AND COMUNICATION TECHNOLOGY GYAMFI SERIES
EXAMPLES:
I. DISKETTES: A FLOPPY DISK IS A CIRCULAR PLASTIC DISK COATED WITH MAGNETICALLY
SENSITIVE. THEY
ARE PACKAGED IN B1/2-INCH HARD PLASTIC CASES. A SLIDING METAL SHUTTER PROTECTS THE
DISK
FROM FINGER PRINTS DUST AND DIRT.

II. Hard disks: it is by far most important storage element and the largest storage devices with highest
capacity. A hard disk is a magnetic storage device which
contains one or more metal plates or disks called platters that
store information. They are made of a
rigid material such as aluminum. Each platter is covered with a
magnetic coating and entire unit is encased in a sealed chamber.
Unlike the diskettes, where the disks and its drive are separated,
the hard disk and drive is a single unit. It includes the hard disk,
the motor that spins the platters, and a set of read/write heads.
Because you cannot remove the disk from the drive (unless it is
a removable or external hard disk).
The terms hard disk and hard drive are used interchangeably. A DISK is the physical
device on which information is stored. E.g. floppy disk, CD, DVD, Blue-ray disk, etc while
a DRIVE is the device used for writing (storing) and reading
(retrieving) information
from a disk. Example includes floppy drive, CD/DVD, and Zip
drive.
Hard disk storage capacities are measured in megabytes or
gigabytes. A disk that can
store 8.4GB for example has room for more than 8,400,000,000
bytes. This
corresponds to more than 2 million pages of printed texts. A full
installation of Microsoft windows 98 requires 200MB space.

Types of hard disk
1. Internal hard disk drive: it is placed inside the system unit and stores the operating
system of the computer as well as other programs and user files.
2. External hard disk drive looks and works almost like the internal one but is
connected outside the system unit through a cable. The external hard disk drive is
portable and can be carried from one computer to another.
b. Optical storage.
(Here we talk of secondary storage which provides permanent or non-volatile storage)
Optical storage device stores data on reflective surface on the disks surface to represent
digital data. Examples are:
i. CD ROM DRIVE: this is an optical drive, which enable computer to read data from computer disk.
Using a standard CD-ROM drive and compact disk, the computer can only read data from the disk and
cannot write data to the disk.
(CD-R) compact Disk Recordable
(CD-RW) Compact Disk Rewritable

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