taher by mn

8/3/2019 taher by MN

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Computer Technology

Dr. Mohamed Taher


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Course Contents

Computer Systems

Data Representation

Flow Chart

Introduction to C/C++ Programming

Operating Systems

Computer Networks

Multimedia


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What is A Computer?

A computer is a device that performs

mathematical and logical operations at high

speed and with precision.

Early computers were used mainly to compute

(add, subtract, multiply, divide and so on).

Today, computers perform a variety of tasks such

as, text, audio and video processing and handling

large quantities of information


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Basic Elements of a Computer System

Main Memory


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5

TYPES OF COMPUTERS Embedded Computers

A computer that is internal component of another machine

NonEmbedded Computers

Microcomputer

The lowest end of the computer range in terms of speed and

storage capacity. personal computers (PC)

Mini Computer

Used in multi-user system

Mainframes

Operate at very high speed, have very large storage capacity

and can handle the work load of many users

Supercomputer

The fastest and most expensive machines. They have highprocessing speed compared to other computers


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Basic Elements of a Computer System

Main Memory


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What is memory?

The computers workspace whereapplication instructions and data are held

during operation is called memory also

known as main memory, primary storage orRAM (Random Access Memory).

The capacity of a memory is important

because this is where data and programs

are stored while they are active, thus

bigger memory means bigger workspace.


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Units in main memory

smallest basic unit = bit

basic unit = byte (B) (1 byte = 8 bits)

1 Kilo (K) =2 10

1 Mega (M)= 220

1 Giga (G) = 2 30


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Input Devices

Any type of device that provides data

to a computer from the outside

world For example:

Keyboard

Mouse

Scanner


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Scanner A computer scanner converts printed or transparent

material into a digital image.

The resolution of a scanner determines the sharpness of

the scan. Resolution is usually measured in dots per inch,

or dpi. The internal electronics in a scanner convert the color

information to digital bits.

This process is called analog-to-digital (or A/D) conversion,

and the quality of the A/D conversion can affect the final

digital output.

Most modern scanners feature 48 bit A/D conversion, or 16

bits for each color.


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Output Devices

Any type of device that provides data from acomputer to the outside world

Examples of output data:

A printed report

An image such as a picture

A sound

Common output devices include:

Monitor (display screen)

Printer


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Display Devices

Output device that visually conveys information Information on display device sometimes

called soft copy

2 Common types CRT

LCD

Featured by Refresh rate

Resolution

Visible screen size


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Working method of CRT monitor

The back of the tube has a negativelycharged cathode, so called electron gun.

The electron gun shoots electrons down

the tube and onto a positively charged

screen. The screen is coated with a

pattern of red, green and blue phosphordots that will glow when struck by the

electron stream. The three dots

together make up a pixel.


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CRT Monitors

How does video travel from the processor to a CRT

monitor?

Step 1.The

processor sends

digital video data to

the video card.

Step 2.The video cards digital-to-analog converter (DAC) converts the

digital video data to an analog signal.

Step 3.Theanalog signal is

sent through a

cable to the CRT

monitor.

Step 4.TheCRT monitor

separates the

analog signal

into red, green,

and blue signals.

Step 5.Electron gunsfire the three color signals

to the front of the CRT.

Step 6.An image isdisplayed on the screen

when the electrons hit

phosphor dots on the back

of the screen.

Video card(also called agraphics card)converts digital

output from computer into analog video signal


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LCD Screen

Liquid crystal panels are constructed by

sandwiching thin layer of liquid crystal

between two electrically conducting plates

By applying proper electrical signals acrossthe plates, various segments of the liquid

crystal can be activated, causing changes in

their light-diffusing or polarizing properties


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Printers

Output device that produces text and

graphics on paper, Result is hard copy, or

printout

In addition, many modern printers can

directly interface to electronic media such as

memory sticks or memory cards, or to image

capture devices such as digital cameras,scanners

Some printers are combined with a scanners

and/or fax machines in a single unit.


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Main types of printers

Dot matrix

Inkjet

Laser


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Dot matrix printer

A dot matrix printer orimpact matrix printerrefers to a type ofcomputer printer with a

print head that runsback and forth on thepage and prints by

impact, striking an ink-soaked cloth ribbonagainst the paper


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Inkjet printersInkjet printers are a type of computer printer that operates

by propelling tiny droplets of liquid ink onto paper. They

are the most common type of computer printer for thegeneral consumer due to their low cost, high quality of

output, and ease of use.

Laser printers are printer that uses laser technology to printimages on the paper. These work in a manner similar to aphotocopier. The laser recreates the image on a negativelydrum. A roller is charged with electricity, then a laser isused to remove the charge from portions of the roller.Powdered ink (toner) sticks to the parts of the roller thatwere hit by the laser, and this toner is transferred from the

roller to the paper. Then the ink is baked into the paperusing a heater

Laser Printers

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