Lesson 1 0x001 001

Lesson 1 0x001

001

The Computer System

Computer Systems / Ch. 1 1

Mohamed ZakiPrincipal Lecturer

Main Topics

• What is a Computer?• General-purpose & Dedicated Computers.• Computer as a system.• Computer hardware system.• Peripherals

– Input Peripherals.– Output Peripherals.– Storage.

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Course Assessment

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Attendance & Contribution

10

Assignments (2) 20Presentation 10Midterm 20Final 40

What is a Computer?

Computer: is a programmable machine that receives input, stores and manipulates data/information, and provides output in a useful format.

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General Purpose and Dedicated Computers

1. General-Purpose computer solves many types of problems, such as (document typing, Drawing, games,..etc)

2. Dedicated Computers is used for only one task.(Control process in the manufacturing industry)

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Remark: In general a dedicated computer is the same as a general-purpose computer in its fundamental construction

General Purpose and Dedicated Computers (cont.)

System: is a set of interrelated components working together to achieve a certain goal.

So, to consider a computer as a system, the computer must contain related components working

together to perform the main functions.

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Computer as a system

Computer Components As a System

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Computer System

Hardware Software

Peripherals Central Processing

System Programs

ApplicationPrograms

Control Unit ALU Main Memory

Input Unit Output Unit SecondaryStorage

1-Computer Hardware Hardware devices can be organized according

to the following system functions:

• Input: Devices that convert data into electronic form in the computer system.

• Output: The output devices are used to convert the electronic information into a human understandable form.

• Processing: The CPU is the main processing component. ALU (Arithmetic Logic Unit) will perform all the processing.

• Storage: Takes place in the primary storage unit of the CPU and in secondary storage units. these devices store data and program instructions are needed for processing.

• Control: control unit of the CPU is the control component of the computer system. It interprets computer program instructions and transmits directions to other components of the computer system.

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Peripherals

Parts of computer that transfer data in and out.

• Input Peripherals.• Output Peripherals.• Secondary Storage.

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Input Peripherals:Devices used for transferring data from the outside

world representation into the internal character code of the computer.

• Keyboard.• Barcode reader: Barcode data can be described as a

sequence of vertical lines vary in thickness, light focuses on and scanned across these lines using a small laser beam, then data can be read and input to computer.

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Other input peripherals:

• Light pens. }• Mice } Pointing devices• Touch screens. }• Digitizers.• Scanners.• Microphones.• Cameras.

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Output Peripherals

• Printers 1- Impact Printer: this method of printing

is based on the impact of a hard object against an ink-coated ribbon, which is then forced on the paper to make it mark the shape of the character.

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Line printersDot matrix printers

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Output peripherals (Impact Printers) (Cont.)

Output peripherals (cont.)2- Non-Impact Printers

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Ink-jet printers.

Thermal printers.

Laser printers.

Comparison between printersDisadvantages Advantages Mechanism Impact/Non-impact Type

Low quality. • Used ordinary papers.

• Not expensive.

It prints a whole line of text at one go.

Impact Line printer

Low speed. noisy

• Used ordinary papers.

• cheap

Use a pattern of dots in the shape of a character.

Impact Dot Matrix

Ink is expensive compared with printer cost.

High speed. Silent. Colored Not expensive.

Sprays a stream of ink on an ordinary paper.

Non-impact Ink-Jet

Slow. Paper is costly.

Silent. Use heat to produce an image on special paper.

Non-impact Thermal

Expensive Large compared with others.

High speed.High quality.Silent.

A laser beam is used to dry up a powdered ink on the paper.

Non-impact Laser

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• Plotters.

• Visual Display Unit(VDU).

• Projectors (Data Show)

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Output peripherals (Cont.)

Secondary Storage

• Optical Storage - CD (Compact Disc) - DVD (Digital Versatile Disc)

• Flash Memory

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Storage Units

1. Bit (Binary Digit): it is the smallest unit to store data,(0 or 1).

2. Byte (B) :it is the basic storage unit of memory. It consists basically of 8 bits. It can hold one symbol only at a time.

3. Kilo Byte (KB)=1024 B =210 B

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Storage Units of Memory

4. Mega Byte (MB)=1024 KB =(1024 x 1024) B =104,8576 B = More than a Million of bytes. =210 x 210=220 B.5. Giga Byte (GB)=1024 MB =(1024 x 1024) KB =(1024 x 1024 x1024) B =104,8576 KB = 1,073,741,824 B = More than a Billion of bytes. =210 x 210 x 210 = 230 B.

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Storage Units

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*

Bit Byte KByte MByte GByte 8 1024 1024 1024

%

Bit Byte KByte GByte TByte 8 1024 1024 1024

TByte 1024

MByte 1024

Refreshing Questions

• The ……………………. Can be described as an input device.

1.Light pen 2.HP laser jet printer 3. Plotter 4.None

• A device used for transferring a paper based image into a computer image is……………….

1. Ink jet printer 2. Scanner 3. Digitizer 4. None

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Refreshing Questions (cont.)

• RPM stands for _________.• DVD stands for _________.• VDU stands for _________.• 10 MB =_____ KB.• Arrange the following in ascending order:

0.6GB, 840MB, 15000KB

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