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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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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