Computer Hardware and Network Essentials_4

8/7/2019 Computer Hardware and Network Essentials_4

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Computer Hardware andNetwork Essentials_4


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Overview

y Storage (Secondary storage)

y Hard Disk Drive

yFloppy Disk Drive (FDD)

y Characteristics of storage devices


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Storage (Secondary storage)

y Storage holds data, instruction and information for future use

(long-term storage).

y Every computer uses storage to hold software, specially, system

software and application software. To start up, a computer locates

an operating system (system software) in storage and loads it intomemory.

y Examples of storage media are ( hard disks, floppy disks, Zip

disks, flash memory, tape, CDs and DVDs)


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Storage device & types ofstorage

y Storage devices have two types of process:

y Writing process:

y Process of transferring items from memory to storage media.

y R

eading process:y Process of transferring items from storage media to memory

y Storage media are two types namely Magnetic and optical.

1. Magnetic media types: [Write and read]

y

Hard Drives - High-capacity storage (100 500 GB)y Floppy Drive - One flexible platter(1.44 MB)

y Zip Drive Magnetic medium that stores 100 MB to 750

MB of data

y

Flash Cards high capacity(1 16 GB)


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Types ofstorage2. Optical media types: [read only]

y Uses lasers to read the binary information from the medium,usually a disc.

y Millions of tiny holes are burned into the surface of the disc.

y

There are two common types of optic mediaa. CD-ROM (Read Only Memory)650MB or 700 MB

y By its definition, CD-ROM is Read Only.

y Special CD drives burn information into blank CDs.

y There are two types of CD-ROM:

y CD-R (compact disc-recordable) you can write on oncey CD-RW (compact disc-rewritable) you can write on.

multiple times.

b. DVD - stands for Digital Versatile Disc, it allows up to 17gigabytes of storage (from 4.7 GB to 17 GB). In addition it can

read CDs.


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How does a hard disk work?

Step 1.

Circuit board controls

movement of head

actuator and a small

motor.

Step 2.

Small motor

spins platters

while computer

is running.

Step 3.

When software

requests a disk

access, read/writeheads determine

current or new

location of data.

Step 4.

Head actuatorpositions read/write

head arms over

correct location on

platters to read or

write data.

y Hard disk is a storage device that contains several inflexible,circular platters that store data electronically.

y Hard disks store digital information in a relatively permanentform.


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Floppy Disk Drive (FDD):

y A Floppy Disk Drive is a device that reads from and writes to

floppy disk

y Floppy disk:

y

write-protect notch is a small opening with a cover that youslide. A notch open means you cannot write on the disk and

when it closed means you can write on the disk.

y The FDD interface cable is used to connect the FDD to the

motherboard.


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How to Choose a PC For Your Business

y The three most important characteristics of computer parts are

speed, cost and capacity.

y Backup is duplicate of file, program, or disk in case original islost, damage, or destroyed. It is very important for using in an

organizations especially banks, hospitals, governments..etc.


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Questions

Documents

Computer Hardware and Network Essentials_4