Chapter 1
An Overview of the
Computer System
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This lesson includes the following sections:
• The Computer System Defined
• Hardware: The Nuts and Bolts of the Machine
• Software: Bringing the Machine to Life
• The Shapes of Computers Today
The Computer System Defined
A computer is an electronic device used to process data,
converting data into information that is useful to people.
A complete computer system includes four distinct parts:
• Hardware
• Software
• Data
• User
The Computer System Defined Hardware:
•
Types of Hardware
•
The CPU
•
Memory
•
How Memory is Measured
•
Input and Output Devices
•
Storage Devices
Hardware: The Nuts and Bolts of the Machine Types of Hardware
A computer’s hardware devices are categorized as follows:
•
Processor
•
Memory
•
Input and Output (I/O devices)
•
Storage devices
Hardware: The Nuts and Bolts of the Machine The CPU
•
The procedure that transforms raw data into useful
information is called processing. This function is
divided between the computer’s processor and
memory.
•
The processor is also called the central processing
unit (CPU). It manages all devices and performs the
actual processing of data.
•
The CPU consists of one or more chips attached to
the computer’s main circuit board (motherboard).
The Central processing Unit
(CPU)
The central processing unit (CPU) contains electronic circuits
that cause processing to occur.
The CPU interprets instructions to the computer, performs the
logical and arithmetic processing operations, and causes the
input and output operations to occur.
It is considered the “brain” of the computer.
It consists of :
1. Control unit (CU)
2. Arithmetic and Logic unit (ALU)
3. Memory unit (MU)
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The Central processing Unit (CPU)
(cont.)
• Control Unit : central system controls the flow of data to
and from the main storage and peripherals.
• Arithmetic and Logic Units : This unit performs
arithmetic operations such as addition ,subtraction
,multiplication and division and Logic operations like
AND, OR, NOT, XOR.
• Memory Unit :Which holds the data in in terms of
Program and files. The data stored can be accessed and
used whenever required by the CPU for necessary
processing.
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Central
Processing
Unit
Hardware: The Nuts and Bolts of the Machine Memory
•
Memory also consists of chips attached to the
motherboard.
•
Memory holds data and program instructions as the
CPU works with them. This memory is called
Random Access Memory (RAM).
•
The CPU can find any piece of data in RAM, when it
needs it for processing.
•
RAM is volatile, meaning it holds data only when the
power is on. When the power is off, RAM's contents
are lost.
Hardware: The Nuts and Bolts of the Machine –
How Memory is Measured
•
The smallest usable unit of memory is measured by
byte – the amount of memory required to hold one
character, like the letter A or the numeral 2.
•
Computers work with larger chunks of data,
measured in multiple bytes, as shown below:
Unit
Approx. Value
(bytes)
Actual Value
(bytes)
Kilobyte (KB)
Megabyte (MB)
Gigabyte (GB)
Terabyte (TB)
1,000
1,000,000
1,000,000,000
1,000,000,000,000
1,024
1,048,576
1,073,741,824
1,099,511,627,776
Hardware: The Nuts and Bolts of the Machine –
Input and Output Devices
•
Input devices accept data and instructions from the
user or from another computer system. The keyboard
and mouse are examples of input devices.
•
Output devices return processed data back to the user
or to another computer system. The printer and
monitor are examples.
•
Communications devices (such as modems and
network interface cards) perform both input and
output, allowing computers to share information.
Hardware: The Nuts and Bolts of the Machine Storage Devices
•
Storage devices hold data (Perminant) not currently
being used by the CPU. Data is commonly stored on
a magnetic or optical disk. Each type of disk uses a
special medium for storing data on its surface.
•
A disk drive is a device that reads data from and
writes data to a disk. Most new computers feature a
floppy disk drive, a hard disk drive, and an optical
disk drive.
•
The most common optical storage devices are CDROM and DVD-ROM drives.
Software: Bringing the Machine to Life
•
What is Software?
•
System Software
•
Application Software
Software: Bringing the Machine to Life –
What is Software?
•
Software is a set of electronic instructions that tells the
computer how to do certain tasks. A set of instructions
is often called a program.
•
When a computer is using a particular program, it is
said to be running or executing the program.
•
The two most common types of programs are system
software and application software.
Software programs create useful output
Software: Bringing the Machine to Life –
System Software
•
System software exists primarily for the computer
itself, to help the computer perform specific functions.
•
One major type of system software is the operating
system (OS). All computers require an operating
system.
•
The OS tells the computer how to interact with the
user and its own devices.
•
Common operating systems include Windows, the
Macintosh OS, OS/2, and UNIX .
Software: Bringing the Machine to Life Applications
•
Application software tells the computer how to
accomplish tasks the user requires, such as creating a
document or editing a graphic image.
•
Some important kinds of application software are:
Word processing programs
Database management
Graphics programs
Web design tools and browsers
Communications programs
Entertainment and education
Spreadsheet software
Presentation programs
Networking software
Internet applications
Utilities
Multimedia authoring
Computer applications
• Computer Database : instead of millions of
folders and papers, it stores data and make
them easy to access and change it ,allow
many users access same data throw
database management system .
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Computer applications (cont.)
• Computer graphics : graphics created by
representation and manipulation of image data
by a computer .
– Examples Used in :
• Graphical user interface
• Games
• Computer animation
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Computer applications (cont.)
• Image processing : extracting image
information .
– Examples Used in :
• Objects and human Recognition
• Detecting manufacture defects
• Enhancement of important images
• Get effects and analyze it
• Medicine - You can diagnose
diseases.
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Computer applications (cont.)
• Computer Networks : connecting computers
with each other and exchange data
– Example : World wide web
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Computer applications (cont.)
• Web sites and applications : is a set of
related web pages and applications accessed
over a network such as the Internet or
intranet.
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Computer applications (cont.)
• Artificial intelligence : is the systems and
applications that undergo the human
intelligence , it can be learned and give
results with very high accuracy
– Such as :
• Neural networks
– Use learning in prediction and recognition
• Genetic algorithms
– Used in getting best solution to problem
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Computer applications (cont.)
• Mobile applications : application software is
developed for low-power handheld devices
– Examples :
• Control computer throw Bluetooth
• Mobile games
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Computer applications (cont.)
• Special purpose Micro systems : systems
which designed to serve special purpose
– Examples :
• ATM machine system
• Banks microsystems
• Robotics :Robots are controlled by software.
– Example:
• Control robot throw software
from cam
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Computer applications (cont.)
• Wireless sensor networks : is a networks of
agents which connected together to perform
a task
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The Computer Generations
1. First Generation Computers (1950's) : Vacuum Tubes
(valves), Low speed, Punched Cards Storage, Expensive .
2. Second Generation Computers (1960's) : start of using
Transistors, Faster, Smaller, Size, Less Expensive.
3. Third Generation Computers (1970's) : Silicon Chips and
IC’s, Main Frame Computers, Magnetic Tape Storage.
4. Fourth Generation (1980's) : Very Large Scale Integration
(VLSI), PCs, Large Memory Sizes, Magnetic Disk Storage.
5. Fifth Generation (Late 1990's) : Laptop, Optical Storage,
Communication, Higher Speed, High Capacity, inexpensive.
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Classification of Computers
(a) According to the purpose of the computer.
(b) According to the operation size of computer.
32
(a) Classification as purpose
1. General Purpose Computers: designed for
general use (PCs, Laptops, . .)
2. Special Purpose Computer : designed to
perform specific processing tasks.
Examples are those found in video games,
cameras, digital watches, washing machines,
robots etc.
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b) According to size and capabilities
The Shapes of Computers Today
•
Supercomputers
•
Mainframe Computers
•
Minicomputers
•
Microcomputers, or Personal Computers
According to size and capabilities(cont.)
 Super computers
• These computers are
characterized as being the
fastest, with very high
processing speed, very large
size, most powerful.
• There are widely used in
complex scientific
applications like processing
geological data, weather
data, genetic engineering etc.
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The Shapes of Computers Today Mainframe Computers
•
Mainframe computers can support hundreds or
thousands of users, handling massive amounts of
input, output, and storage.
•
Mainframe computers are used in large
organizations where many users need access to
shared data and programs.
•
Mainframes are also used as e-commerce servers,
handling transactions over the Internet.
Mainframe
System
The Shapes of Computers Today Minicomputers
•
Minicomputers are smaller than mainframes but
larger than microcomputers.
•
Minicomputers usually have multiple terminals.
•
Minicomputers may be used as
• Network servers
• Internet servers.
The Shapes of Computers Today –
Microcomputers, or Personal Computers
•
Microcomputers are more commonly known as persona
computers. The term "PC" is applied to IBM-PCs or
compatible computers desktop computers .
•
Notebook (laptop) computers are used by people who
need the power of a desktop system, but also portability.
•
Handheld PCs such as PDAs (Personal Digital Assistant)
lack the power of a desktop or notebook PC, but offer
features for users who need limited functions and small
size.
lesson 1 review:
Essential concepts
•
Name the four parts of a computer system.
•
State the main components of the computer hardware.
•
Differentiate between computer memory and external
storage.
•
Differentiate between the two main categories of
computer software.
•
Compare the five most common types of computer
systems according to size and capability.
•
Differentiate between the two main categories of
computer systems according to purpose of use, giving
examples.