Introduction To Computer System

Chapter 1

Prepared By :

Dr. Sherif Elseuofi

IntroductionWhat is the Computer ?

The Computer is a set of independent physical components and devices (Hardware), which have a specific job to do for each one and working together by Software to make up the computer system.

Arithmetic operations

Operation In Math In Computer

addition + +

Subtraction - -

Multiplication × *

division ÷ /

Are the four known math operations which are :

And any other operation that’s refers to them like: square root, sine, cosine, tan ….

Logical operations

are the operations that have a result of either TRUE or FALSE but not together.

like comparisons in math:

Description In Math In Computer

Greater than > >Greater than or equal ≥ >=

Less than < <Less than or equal ≤ <=

Equal = =Not equal ≠ <>

Data

• Raw, unprocessed facts• Processed data becomes information• Stored electronically in files– Document files– Worksheet files– Database files– Presentation files

Processing

Performing computer operations like arithmetic & logical operations on an entered set of data , in order to output information that is useful for the user.

Information

Is a set of results that are output from the computer after processing the data.

User

• is the one who makes use of the computer, entering data and getting information like:

1) Human

2) Another computer

Information Technology

• It refers to anything related to computing technology, such as networking, hardware, software, the Internet, or the people that work with these technologies.

• is a term that encompasses all forms of technology used to create, store, exchange

Computer Tasks:

Storage

Input

• When a computer is asked to do a job, it handles the task in a very special way. • It accepts the Data from the user.

This is called input.

Storage

• It stored the information until it is ready for use. The computer has memory chips, which are designed to hold information until it is needed.

Processing

• It processes the Data. The computer has an electronic brain called the Central Processing Unit, which is responsible for processing all data and instructions given to the computer.

output

• It then returns the processed information to the user. This is called output.

Microprocessor

 •Central Processing Unit (CPU)

 •Two Basic Components  –Control unit

 –Arithmetic-logic unit (ALU)

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Central Processing Unit (CPU)

• is the electronic brain of the computer• The CPU in a personal computer is usually a

single chip• It organizes and carries out instructions that

come from either the user or from the software.

 •

 •

 •

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System Board

Connects all components

Allows communication between devices

Main board or motherboard

Circuit boardelectronic components

 –Sockets

 –Slots  –Bus lines

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Motherboard

The motherboard is a rigid rectangular card containing the circuitry that connects the processor and all the other components that make up your personal computer.

Uses of Computer system

• Use Of Computers In Education• Uses of computer in business• Uses of Computers in Hospitals• Uses of Computers in Airports

Use Of Computers In Education

• The use of computers in the education sector has increased greatly over the past few years

Advantage of Computers In Education

• Computers are the best way of teaching subjects to students• Computers assist teachers in teaching

their students easily and quickly.• Students can search for the concepts

or things which they wish to know, by referring to relevant websites.

Advantage of Computers In Education

• The students can be shown charts, diagrams and figures while teaching practical oriented subjects • Introduction of computers in

educational institutes can help students learn different software and hardware

Disadvantage of Using Computers In Education

• Doing all calculations with the help of software and calculator can affect our own mathematical ability.• With ready-made information available

on the Internet, students will not take any interest in reading reference books and searching for information using other sources.

Uses of computer in business

• computers can be used in business from the stage of manufacturing till the stage of its sale.

• Computers can keep records of all the employees and prepare their pay cheques in a fraction of minutes every month.

• A computer can easily carry out automatic checks on the stock of a particular item.

Uses of Computers in Hospitals

Some uses of computers in hospitals do not involve treating patients but help medical staff and doctors to handle information and data in a better manner.

Application of Computers in Hospitals

• Handling Medical Data

• Scanning and Imaging

• Examination and Monitoring

Advantages of Computers in Hospitals

• Precise 'tests' and medical examinations• Faster medical alerts, which are more accurate

time-wise• Enhanced data about a patients medical

history• Precision in diagnosis• Precision in billing• Automated updating of medical history

Uses of Computers in Airports

• Keep track of the planes' locations, speed, direction, status, etc.

• Monitor security devices like cameras, x-ray machines, and metal detectors

• Keep up with the departure/arrival status • Communicate over screens audio systems, and

paging devices • It is used for saving, who have booked the

tickets

Computer Generations

• First• Second• Third• Fourth

The first generation computers were huge, slow, expensive, and often undependable.

The First Generation: 1946-1958 (The Vacuum Tube Years)

IBM 360 Computer System

The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do

The First Generation: 1946-1958 (The Vacuum Tube Years)

•In 1947 three scientists working at AT&T's Bell Labs invented what would replace the vacuum tube forever.

• This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.

The Second Generation: 1959-1964 (The Era of the Transistor)

The First Transistor (1946-1958)

•Faster, more reliable, smaller, and much cheaper to build than a vacuum tube.•One transistor replaced the equivalent of 40 vacuum tubes• transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass.

Transistor

IBM 704

Used discrete transistors

•The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of silicon.

The Third Generation: 1965-1970 (Integrated Circuits-Minimizing the

computer)

•The number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power.

The Third Generation: 1965-1970 (Integrated Circuits-Minimizing the

computer)

Third Generation

Left: DEC PDP-8, c. 1965

Right: DEC PDP-11, c. 1970

•These third generation computers could carry out instructions in billionths of a second.•The size of these machines dropped to the size of small file cabinets.

The Third Generation: 1965-1970 (Integrated Circuits-Minimizing the

computer)

•This generation can be characterized by : monolithic integrated circuits (millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer)

The Fourth Generation: 1971-Today (The Microprocessor)

• By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers.

The Fourth Generation: 1971-Today (The Microprocessor)

Computer system components

Chapter 2

1. Computer Hardware2. Computer Software3. Computer User

Computer system components

1. Input unit:•Keyboard•Mouse•Scanner•Microphone•CD-ROM• Joystick

Computer Hardware

2. Processing unit

• Central Processing unit (CPU)• Arithmetic & Logical unit (ALU)• Control unit• Registers

Computer Hardware

Registers• one of a small set of data holding places

that are part of a computer processor .

• A register may hold a computer instruction , a storage address, or any kind of data (such as a bit sequence or individual characters).

Computer Hardware

Data Registers:is the register of a computer's control

unit that contains the data to be stored in the computer storage

Computer Hardware

Address Registers :is a CPU register that either stores the

memory address from which data will be fetched to the CPU or the address to which data will be sent and stored.

Computer Hardware

Status Registers :is a hardware register which contains information about the state of the processor

Computer Hardware

Program counter :Is a register in a computer processor that contains the address (location) of the instruction being executed at the current time.

Computer Hardware

3. Memory Unit

• Main Memory Unit• Secondary Memory Unit

Computer Hardware

Main Memory Unit:• Random Access Memory (RAM):

memory where data and program instructions are stored while the computer is in operation. This is temporary memory.

Computer Hardware

Main Memory Unit:• Read Only Memory (ROM):

Is a small area of permanent memory that provides startup instructions when the computer is turned on. You can not store any data in ROM. The instructions in ROM are set by the manufacturer and cannot be changed by the user.

Computer Hardware

Secondary Memory Unit:• Hard disk• Floppy disk• Tape drive• CD-ROM• Flash Memory

Computer Hardware

4. Output Unit

1. Monitor 2. Speakers3. Printer

Impact Dot Matrix

Non-ImpactInk JetLaser

Computer Hardware

1. System SoftwareAn operating system (sometimes

abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer.

Computer Software

2. Application SoftwareGeneral purpose Software

Application software is any software used for specified applications such as:

Word ProcessingSpreadsheet

DatabasePresentation Graphics

Communication Tutorials

Entertainment, Games

Computer Software

Classification of Computers

Chapter 3

1. Size2. Data Handled3. Purpose Of Use

Classification of Computers According To:

1. Microcomputers, or Personal Computers :

Two major types of these computers are laptop or Desktop computers. Only one user uses these computers at time that's why they are also known as personal computers.

Size

2. Minicomputers : These are powerful computer. These

computers come into existence in 1960s at that time mainframe computer was very costly. Mini computers were available in cheap prices, so users start using it.

Size

3. Mainframe Computers :• It as a very powerful and large computer. it can

handle processing of many users at a time.• Terminals are used to connect a user to this

computer and users submit there task through mainframe

• Terminal is a device which has keyboard and a screen. By using terminal users put inputs into the computer and get the output through screen.

Size

4. Supercomputers :

These are most powerful computers even than mainframe.

Size

1. Analog:• Analog computers are used to process

continuous data. • Analog computers represent variables by

physical quantities.• which solve problem by translating physical

conditions such as flow, temperature, pressure, angular position or voltage

Data Handled

2. Digital:• Digital computer represents physical

quantities with the help of digits or numbers.

• These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.

Data Handled

3. Hybrid:

• Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system.

Data Handled

1. General Purpose Computers:

• can process business data as readily as they process complex mathematical formulas.

• General-purpose computers can store large amount of data and the programs necessary to process them.

Purpose Of Use

2. Special Purpose Computers:

• designed to solve a specific problems; the computer program for solving the problem is built right into the computer.

Purpose Of Use

Computer Networks

Chapter 4

A computer network is a system for communication among two or more computers.

Definition

1. Sharing Devices :Peripherals such as printers can be shared amongst many different users.

2. Saving cost:Terminals are cheaper than standalone PCs.

3. Sharing resources :Software can be shared amongst different users.

4. Sharing data :Data can be shared between different authorized users.

5. Communication : Communication (Telephone calls, E-mails, Chatting …. Etc) across the network is cheap and fast.

Advantages

1. Cabling can be expensive to install and replace.

2. A fault with the server will prevent the whole network from working.

3. Security measures are needed to restrict access to the network.

4. WANs are vulnerable to hackers and viruses.

Disadvantages

1. By geographical range:

•Personal Area Network (PAN) •Local Area Network (LAN) •Metropolitan Area Network (MAN) •Wide Area Network (WAN)

Classification of Computer network

2. By functional relationship

•client-server •multitier architecture •Peer-to-peer

3. By network topology •bus network •star network •ring network

Classification of Computer network

What is a Protocol?A protocol is a set of rules that governs the communications between computers on a network.

Networking HardwareNetworking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and

communications within the network.

File/Network Servers These are very fast computers with a large amount of RAM and storage space, along with a one or more fast network interface card(s).

Workstations •A computer that is configured with a network interface card, networking software, and the appropriate cables. •Workstations do not necessarily need large storage hard drives, because files can be saved on the file server.• Almost any computer can serve as a network workstation.

Laptops/Mobile Devices These devices typically have modest internal storage, but enough power to serve as a workstation for users on the go. These machines nearly always have a wireless adapter to allow quick network connections without cumbersome cabling.Network Interface Cards (NIC)•The physical connection between the network and the computer workstation. Most NICs are internal

Ethernet Cards

•Ethernet cards are usually included with a computer

•connections for either coaxial or twisted pair cables

Wireless Adapters Are found in most portable devices, such as laptops, smart phones, and tablet devices.

Switches •A device that provides a central connection point for cables from workstations, servers, and peripherals.•That is they electrically amplify the signal as it moves from one device to another

Repeaters •The repeater electrically amplifies the signal it receives and rebroadcasts it. •They are used when the total length of your network cable exceeds the standards set for the type of cable being used.

Bridges •Is a device that allows you to segment a large network into two smaller, more efficient networks.

Routers •Are the traffic directors of the global internet•Determine appropriate paths for packets destined for any address

Firewalls •Is a networking device that is installed at the entrance to a LAN when connecting a networks together, particularly when connecting a private network to a public network, such as the internet.•Protect the private network users and data from malevolent hackers. •Firewalls are either hardware or software

What is Network Cabling? •Cable is the medium through which information usually moves from one network device to another.Types of Cables:•Unshielded Twisted Pair (UTP) Cable •Shielded Twisted Pair (STP) Cable •Coaxial Cable •Fiber Optic Cable

Unshielded / shielded Twisted Pair (UTP) Cable:

RJ-45 connector

Coaxial Cable

BNC connector

Fiber Optic Cable

BNC connector

What is a topology? refers to the configuration of cables, computers, and other peripherals.Main Types of Physical Topologies •Linear Bus•Star•Tree (Expanded Star)

Linear Bus consists of a main run of cable with a terminator at each end .

Advantages of a Linear Bus Topology

•Easy to connect a computer or peripheral to a linear bus. •Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

•Entire network shuts down if there is a break in the main cable. •Terminators are required at both ends of the backbone cable. •Difficult to identify the problem if the entire network shuts down. •Not meant to be used as a stand-alone solution in a large building.

Star A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator

Advantages of a Star Topology •Easy to install and wire. •No disruptions to the network when connecting or removing devices. •Easy to detect faults and to remove parts.

Disadvantages of a Star Topology

•Requires more cable length than a linear topology. •If the hub, switch, or concentrator fails, nodes attached are disabled. •More expensive than linear bus topologies because of the cost of the hubs, etc.

Tree or Expanded Star A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable

Advantages of a Tree Topology •Point-to-point wiring for individual segments. •Supported by several hardware and software venders.

Disadvantages of a Tree Topology •Overall length of each segment is limited by the type of cabling used. •If the backbone line breaks, the entire segment goes down. •More difficult to configure and wire than other topologies.

General Computer Topics

Chapter 5

Computer CrimesComputer crime refers to any crime that involves a computer and a network.•Computer viruses : A computer virus is a computer program that can replicate itself and spread from one computer to another.•Denial-of-service attacks: is an attempt to make a machine or network resource unavailable to its intended users.•Malware: is software used or created to disrupt computer operation, gather sensitive information•Spam: sending of bulk email for commercial purposes•Fraud : Computer fraud is any dishonest misrepresentation of fact

Computer Viruses

• A computer virus is an application program designed and written to destroy other programs.

• It has the ability to: Link itself to other programs Copy itself (it looks as if it repeats itself)

• Infects programs, documents, databases and more …• It is man-made• It can hide and reproduce• It can lay dormant (inactive) and then activate

Sources of Computer Viruses•The Internet :Via downloads and exchanges•Secondary storge: Exchanging disks•Computer networks : Can spread from one network to

How do you know if you have a virus?•Lack of storage capability•Decrease in the speed of executing programs•Unexpected error messages•Halting the system