Lesson 1

The Computer

Computer Systems / Ch. 1 1

Mohamed ZakiPrincipal Lecturer

Main Topics

• What is a Computer?• Computer system.• Peripherals

– Input Peripherals.– Output Peripherals.– Storage.

• Units

Computer Systems / Ch. 1 2

What is a Computer?

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

Computer Systems / Ch. 1 3

General Purpose Computer

1. General-Purpose computer used in many applications, such as (document typing, Drawing, communication, games,..etc)

Computer Systems / Ch. 1 4

Computer Components As a System

Computer Systems / Ch. 1 5

Computer System

Hardware Software

PeripheralsCentral

ProcessingSystem

ProgramsApplicationPrograms

Control Unit ALU Main Memory

Input Unit Output Unit SecondaryStorage

MS-WordMS-ExcelMS-Power PointMS- Access

MS-Windows

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.

Computer Systems / Ch. 1 6

Peripherals

Parts of computer that transfer data in and out.

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

Computer Systems / Ch. 1 7

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.

Computer Systems / Ch. 1 8

Other input peripherals:

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

Computer Systems / Ch. 1 9

Secondary Storage

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

• Flash Memory

Computer Systems / Ch. 1 10

Storage Units

• Bit (Binary Digit): it is the smallest unit to store data,(0 or 1).• 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 such as “A”, “a” , “$” and so on. Symbols are converted into binary codes

• Kilo Byte (KB)=1024 B =210 B

Computer Systems / Ch. 1 11

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.

Computer Systems / Ch. 1 12

Storage Units

%

Bit

Byte

KByte

GByte

MByte

TByte

*

8

1024

1024

1024

1024

Refreshing Questions

• 10 MB =_____ KB.

Computer Systems / Ch. 1 14

Which program allows you to produce letters, memos etc. 

A. Database ApplicationB. Photo editingC. Web browsingD. Word processing

Refreshing Questions

Computer Systems / Ch. 1 15

Which one of the following used as input device? 

a) Printerb) Monitorc) Scannerd) Plotter

Refreshing Questions

• List main four types of Hardware, and give one example for each.

Computer Systems / Ch. 1 16