Introduction to it
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Introduction to IT. Csaba Nagy László Várallyai Email address: [email protected] [email protected] How do computers work?. What is Information Technology?.

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Introduction to it

Introduction to IT

Csaba Nagy

László Várallyai

Email address:

[email protected]

[email protected]

How do computers work?

What is information technology

What is Information Technology?

  • „The branch of engineering that deals with the use of computers and telecommunications to retrieve and store and transmit information”

  • Information Technology is concerned with the use of technology in managing and processing information, especially in large organizations.



What are algorithms

What are Algorithms?

  • In computing, an algorithm is a finite set of instructions, an explicit, step-by-step process for solving a problem, or executing an idea.

  • In simple words, the algorithm is the basic technique used to get the job done.


Example of an algorithm

Example of an algorithm

  • Let's say that you have a friend arriving at the airport (Liszt Ferenc Terminal 2), and your friend needs to get from the airport to your house (near Kalvin square). Here are three different algorithms that you might give your friend for getting to your home:

  • The taxi algorithm:

  • Go to the taxi stand.

  • Get in a taxi.

  • Give the driver my address.

Example of an algorithm 2

Example of an algorithm (2.)

  • The rent-a-car algorithm:

  • Take the shuttle to the rental car place.

  • Rent a car.

  • Follow the directions to get to my house.

  • The bus algorithm:

  • Outside baggage claim, catch bus number 200E.

  • Transfer to Subway M3 on Kőbánya-Kispest.

  • Get off on Kálvin Square.

  • Walk two blocks north to my house.

The goal

The Goal

  • All of these algorithms accomplish exactly the same goal, but each algorithm does it in completely different way. Each algorithm also has a different cost and a different travel time. Taking a taxi, for example, is probably the fastest way, but also has the highest initial cost. Taking the bus is definitely less expensive, but a whole lot slower. You choose the algorithm based on the circumstances.

Types of algorithms

Types of Algorithms

  • Natural Language

    • In Human understandable language

  • Programming Language

    • In specific programming language using necessary precision

  • Pseudo-code

    • It is a mixture of natural language and programming language

Instruction precisity

Instruction Precisity

  • Imprecise Instructions

    - Job can often be done even if the instructions are not followed precisely

  • Modifications may be done by the person following the instructions

  • Computers need to be told in precise manner what to do. Instructions cannot be vague or ambiguous.

Main description of algorithms

Main Description of Algorithms

  • Flow Charts

  • PseudoCodes



Somewhere between human language such as English and Computer languages.

Precise enough to describe what is meant without being tedious.

Flow charts

Flow Charts

  • A Flow Chart is a common type of chart, that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. Flowcharts are used in analyzing, designing, documenting or managing a process or program in various fields


Introduction to it

Computer Science can be considered as the study of algorithms including

  • their formal properties,

  • their hardware and software realisations

  • their applications.

  • Computer is a machine on which algorithms can be implemented.


Personal computer

Personal Computer

  • A PC is a general purpose tool built around a microprocessor.

  • It has lots of different parts -- memory, a hard disk, a modem, etc. -- that work together.

  • General purpose" means that you can do many different things with a PC. You can use it to type documents, send e-mail, browse the Internet and play games.

Pc continued

PC - continued

A PC is a general-purpose informationprocessing device. It can take information from a person (through the keyboard and mouse), from a device (like a pendrive or CD) or from the network (through a modem or a network card) and process it. Once processed, the information is shown to the user (on the monitor), stored on a device (like a hard disk) or sent somewhere else on the network (back through the modem or network card).

The organisation of a computer

The organisation of a computer

Binary numbers

Decimal number system:

789 = 7102+ 8101 + 9100

Binary number system:

1001 = 123+ 022 + 021 + 120 = 9

Basics of Information Technology

Binary Numbers

Decimal to binary


43/2 -----> Quotient: 21 Remainder 1

21/2 -----> Quotient: 10 Remainder 1

10/2 -----> Quotient: 5 Remainder 0

5/2 -----> Quotient: 2 Remainder 1

2/2 -----> Quotient: 1 Remainder 0

1/2 -----> Quotient: 0 Remainder 1

(43)10 = (101011)2

Decimal to Binary

A bit of excercise for you

A bit of excercise for you

  • Translate the decimal number ‘31’ into a binary number!

  • And the answer is…

  • ‘11111’, which comes from…

  • 1*24 + 1*23 + 1*22 + 1*21 + 1* 20

  • Translate the decimal number ‘100001’ into a decimal form!

  • Not too tricky…

  • The answer is ‘33’, since you have only 1*25 which is ’32’ + 1*20 , which is ‘1’

Binary numbers1

Using k bits, we can represent numbers from 0 to 2k-1 (if only doing non-negative numbers)

Addition, Subtraction etc on binary numbers in a way similar to that of decimal numbers

0+0 = 0

1+0 = 1

0+1 = 1

1+1 = 0 with carry 1

Binary Numbers



  • Technology in which, all data can be transformed to sigh serial contained only 0 or 1 digit.

  • 1 Byte = 8 bit

  • 1 Kbyte = 1024 Byte

  • 1 Mbyte = 1024 KByte

  • 1 Gbyte = 1024 MByte.

  • 1010 = 10102

  • 01000001 = 6510 the code of „A”

  • 111111112 = FF16

Representation of data

Data are stored and transformed in digitalization system.

The different type of data have different form:- text -> code tables- numerical ->diff. dig. formats- picture, sound -> spec. formats- audio, video ---> Via a process of digitization.

The programs are stored also in digitized format.

Representation of Data

Main components of a typical desktop computer

Main components of a typical desktop computer

  • Motherboard

  • CPU

  • RAM

  • Video Card

  • Power Supply

  • Hard Drive

  • (Optical Drive)


Logical parts of computers

Logical Parts of Computers

  • Memory

  • CPU

  • Peripherals

What is memory

What is Memory?

  • Memory is the electronic holding place for instructions and data that your computer's microprocessor can reach quickly. When your computer is in normal operation, its memory usually contains the main parts of the operating system and some or all of the application programs and related data that are being used.

Comments memory

Memory Element: Flip Flop.State: 0 or 1.

Change state: based on circuit at each TIME STEP.

Memory is the functional unit of computer thatstores instructions and data.

Memory is divided into fixed size units called cells, currently 8 bits --- called byte

Each memory cell has an address. Note that k bits can beused to address 2k memory cells/bytes.

Comments: Memory

Different types of memory

Different types of memory

  • RAM

  • ROM

  • Cache

  • Dynamic RAM

  • Static RAM

  • Flash memory

  • Memory Sticks

  • Virtual memory

D ifferent t ype s of m emory

Different Types of Memory

  • RAM (random-access memory): This is the same as main memory. When used by itself, the term RAMrefers to read and write memory;. As soon as the power is turned off, whatever data was in RAM is lost.

  • ROM (read-only memory): Computers almost always contain a small amount of read-only memory that holds instructionsfor starting up the computer. Unlike RAM, ROM cannot be written to.

Dynamic ram

Dynamic RAM

  • Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM).

Introduction to it

The capacitor in a dynamic RAM memory cell is like a leaky bucket.It needs to be refreshed periodically or it will discharge to 0.

This refresh operation is where dynamic RAMgets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.

Static ram

Static RAM

  • A particular type of RAM, static random access memory (SRAM), is used primarily for cache. SRAM uses multiple transistors, typically four to six, for each memory cell. It has an external gate array that switches, or flip-flops, between two states. This means that it does not have to be continually refreshed like DRAM. Each cell will maintain its data as long as it has power. Without the need for constant refreshing, SRAM can operate extremely quickly. But the complexity of each cell make it prohibitively expensive for use as standard RAM.


D ifferent type s of memory ii

Different types of memory II.

  • PROM(programmable read-only memory): A PROM is a memory chip on which you can store a program. But once the PROM has been used, you cannot wipe it clean and use it to store something else. Like ROMs, PROMs are non-volatile.

  • EPROM(erasable programmable read-only memory): An EPROM is a special type of PROM that can be erased by exposing it to ultraviolet light.

  • EEPROM (electrically erasable programmable read-only memory): An EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge.

Introduction to it


  • All of the components in your computer, such as the CPU, the hard drive and the operating system, work together as a team, and memory is one of the most essential parts of this team. From the moment you turn your computer on until the time you shut it down, your CPU is constantly using memory. Let's take a look at a typical scenario:

You turn the computer on

You turn the computer on.

  • The computer loads data from read-only memory (ROM) and performs a power-on self-test (POST) to make sure all the major components are functioning properly. As part of this test, the memory controller checks all of the memory addresses with a quick read/write operation to ensure that there are no errors in the memory chips. Read/write means that data is written to a bit and then read from that bit.

Loading operating system

Loading Operating System

  • The computer loads the basic input/output system (BIOS) from ROM. The BIOS provides the most basic information about storage devices, boot sequence, security, Plug and Play (auto device recognition) capability and a few other items.

  • The computer loads the operating system (OS) from the hard drive into the system's RAM. Generally, the critical parts of the operating system are maintained in RAM as long as the computer is on.

Loading applications

Loading Applications

  • When you open an application, it is loaded into RAM. To conserve RAM usage, many applications load only the essential parts of the program initially and then load other pieces as needed.

  • After an application is loaded, any files that are opened for use in that application are loaded into RAM.

The process

The Process

  • In the list above, every time something is loaded or opened, it is placed into RAM. This simply means that it has been put in the computer's temporary storage area so that the CPU can access that information more easily. The CPU requests the data it needs from RAM, processes it and writes new data back to RAM in a continuous cycle.

The process cont

The Process (cont.)

  • In most computers, this moving of data between the CPU and RAM happens millions of times every second. When an application is closed, it and any accompanying files are usually deleted from RAM to make room for new data. If the changed files are not saved to a permanent storage device before being purged, they are lost.

Introduction to it


  • Abbreviation of Central Processing Unit.The CPU(s) is (are) the brain(s) of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place (Exception: wherethere is a dedicatedgraphicscard, and user is runninge.ghighresolutiongames, orengineeringsoftwares)In terms of computing power, the CPU is the most important element of a computer system.

  • Computer runs a STORED program.

  • This stored program can be arbitrary.

  • The basic architecture we discuss is called Neumann Architecture.

The principles of neumann jan o s

The principles of Neumann Janos

1. Computer is processingdatasequentially.

The machinecarries out instructionsonebyone. Neumann thought, electriccomputerscould be fastenoughwithoutparallelism. However most of today’scomputersaresequential, therearemultiprocessorcomputersabletoperformmultipletaskinthesametime.

2. Computer usesbinaryquotation and it is fullyelectronic.

Binaryquotationcan be implementedwith 2-state circuits (1-higher voltage, 0-lower voltage) withtheuse of vacuumtubes, transistors, complexintegratedcircuits.

3. Computer has internalmemory.

Neumann suggestedusinginternalmemorytostorepartialresultsinordertomake computer capable of carrying out a set of operationswithoutanyuserinteraction. Nowadaysweusesemi-conductormemorycontainingintegratedcircuits.

The principles of neumann janos

The Principles of Neumann Janos

4. Stored program concept.

Instructionscan be denotedwithnumbers, sotheycantreatedasdata and can be storedinmemory. Inthisway, computer canworkonitsown, itretreivesdata and instructionsfromthememory. Naturallythedata and theinstructionsarelocatedindifferentparts of thememory.

5. Computer is universal.

There is no needtomakespecialdevices, machinestoperformdifferent computer tasks. Turing proovedwithmathematicallogicaltoolsthat a machinecapabletoperformsomeelementaryoperationscancarry out anykind of calculations.

Important components of cpu

Important Components of CPU:

Control Unit --- brain of the CPU. It decides which operations are to be performed and when.

  • Arithmetic Logic Unit (ALU): Consists of logical circuits for doing addition, multiplication etc.

  • Buses: The buses are wires which connect different parts of the CPU and the parts of the CPU to other components of the computer.

Introduction to it

Instruction Execution:

CPU repeatedly executes the instruction cycle.

1. Fetch the instruction from memory

2. Decode the instruction

3. Execute the instruction (including the setting up for the next instruction to be executed)(Control signals are used to select which operation is to be done.)

Permanent data storage systems

Permanent Data storage systems:

  • serial data storage - on tape, (DAT), features (slow(?), cheap, - archive purpose)

  • random access (disk)

    What does it mean?The disk is turning, while the read and write head is moving over the disk surface

The four most important characteristics of storage devices

The four most important characteristics of storage devices:

  • Speed and access time

  • Cost / Removable versus non-removable

  • Capacity

  • Type of access

Introduction to it


Nearly every desktop computer, laptop and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them.

Hard disks store digital information in a relatively permanent form.

Hard disk drives and direct access

Hard Disk Drives and Direct Access

Capacity and performance

Capacity and Performance

  • A typical desktop machine will have a hard disk with a capacity of between 80 gigabytes and 1 terabyte. Data is stored onto the disk in the form of files. A file is simply a named collection of bytes.

  • No matter what it contains, however, a file is simply a string of bytes. When a program running on the computer requests a file, the hard disk retrieves its bytes and sends them to the CPU one at a time.

Introduction to it

Storing the Data

Data is stored on the surface of a platter in sectors and tracks. Tracks are concentric circles, and sectors are pie-shaped wedges on a track, like this:

A typical track is shown in yellow; a typical sector is shown in blue. A sector contains a fixed number of bytes -- for example, 256 or 512., sectors are often grouped together into clusters.

Other storage ideas

Other storage ideas:

  • SSD: is a data storage device that uses solid-state memory to store persistent data. An SSD emulates a hard disk drive interface, thus easily replacing it in most applications.





Keyboard, Monitor, printers, speakers, etc.


  • Peripherals differ from computer to computer.

  • Easy addition/removal/replacement of I/O devices should be allowed.

  • Design of computer should be flexible to allow this.

  • Grouping of peripherals : input devicesoutput devices

Input devices

Input Devices

  • Human input devices

    • Allow person to send data to the computer

    • Keyboard

    • Mouse (and other pointing devices)

  • Machine-readable input devices

    • Send data directly to computer without human involvement

    • No human involvement means no human error

    • Usually faster than human input

Input devices keyboard

Input devices: Keyboard

  • Keyboards are designed for the input of text and characters and also to control the operation of a computer.

  • To produce some symbols requires pressing and holding several keys simultaneously or in sequence.

  • A keyboard is also used to type commands in a computer. One famous example on the PC is the Ctrl+Alt+Del combination. With current versions of Windows, this brings up a menu-window including options for handling currently-running applications and shutting down the computer, amongst other things.

Inside the keyboard

Inside the Keyboard

  • A keyboard is a lot like a miniature computer. It has its own processor and circuitry that carries information to and from that processor.

  • A large part of this circuitry makes up the key matrix.

Input devices m ouse

Input devices: Mouse

  • A mouse is a small device that a computer user pushes across a desk surface in order to point to a place on a display screen and to select one or more actions to take from that position.



Machine readable input devices

Machine-readable Input Devices

  • Bar code scanners

    • Uses light to read series of coded stripes

  • Optical Character Recognition (OCR)

    • Software that works with scanner

    • Translates scanned digital image to character that user can recognize and manipulate

  • Magnetic Ink Character Recognition (MICR)

    • Character recognition technology used by banks to allow rapid routing of checks between banks

Introduction to it

Display technology

Display Technology

  • The display is the most-used output device on a computer. The display provides instant feedback by showing you text and graphic images as you work or play.

  • Most desktop displays use liquid crystal display (LCD) or cathode ray tube (CRT) technology, while nearly all portable computing devices such as laptops incorporate LCD technology

Standards and resolution

Standards and Resolution

  • Resolution refers to the number of individual dots of color, known as pixels, contained on a display. Resolution is expressed by identifying the number of pixels on the horizontal axis (rows) and the number on the vertical axis (columns), such as 1024x768. Resolution is affected by a number of factors, including the size of the screen.

Measures of monitor

Measures of monitor

  • The measure of screen 14”,…17”…25- The measure of pixel- The number of rows and columns from 640x480 to 1920x1080 (HD)- The frequency of refresh the screen- The numbers of colours, max. 16,7 million

Introduction to it

Hi-resolution monitors come in two types:

  • Cathode ray tube (CRT) - Streams of electrons make phosphors glow on a large vacuum tube. This technology is now obsolete.

  • Liquid crystal display (LCD) - A flat panel display that uses crystals to let varying amounts of different coloured light to pass through it.Developed primarily for portable computers


P rinters


  • Printer prints

    • character symbols

    • Graphics

  • Output quality is measured in dpi dots per inch

  • Printers vary from 60 to 1500 dpi

  • 600 dpi seems common

Types of printers impact

Types of printers: impact

  • Forms characters or images by mechanic strikes of a print hammer or wheel.

  • Most common form is STILL the dot matrix printer

    • Head with small pins (9, 24)

    • Strike ribbon against paper

    • Do 72 to 144 dpi, 30 to 400 chars

    • Noisy

    • Image may smear

Types of printers non impact

Types of printers: non-impact

  • Form characters and images without physical contact

  • Less moving parts, less noise

  • Two forms

    • Laser printer

    • Inkjet printer

Introduction to it

Ports & Cables (Serial port)

  • A port is a connectingsocketorjackontheoutside of thesystem unit intowhicharepluggeddifferentkinds of cables.

  • Serial port - sendsbitsoneat a time, oneafteranother

  • Parallel port

  • SCSI port

  • USB port

  • FireWire port

  • Infrared port

  • HDMI port

  • Etc.

Multimedia i o devices

Multimedia I/O Devices

  • Music, images, and video

    • Convert content to digital form

    • Digital cameras ; digital camera phones

    • Digital Video DVD recorders

  • Voice recognition

  • Text-to-speech

  • Brain wave input

Types of computers

Types of Computers

  • Supercomputers

  • Mainframes

  • Minicomputers

  • Workstations

  • Desktop computers

  • Notebook computers (laptops)

  • Netbooks

  • Handheld computers (PDAs)

Thank you for your attention

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