Introduction to IT

1. Introduction to IT Csaba Nagy László Várallyai Email address: n_csaba@freemail.hu varal@agr.unideb.hu How do computers work?

2. 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. • http://www.youtube.com/watch?v=Gt8xiJyJ2Sc • http://www.youtube.com/watch?v=cWNEZLbP9Lk&NR=1

3. 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. • http://www.youtube.com/watch?v=f60lniJ1toI

4. 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.

5. 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.

6. 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.

7. 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

8. 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.

9. Main Description of Algorithms • Flow Charts • PseudoCodes

10. PseudoCode Somewhere between human language such as English and Computer languages. Precise enough to describe what is meant without being tedious.

11. 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 • http://www.youtube.com/watch?v=z_npAN1QNiE&feature=related

13. 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. • http://www.youtube.com/watch?v=87uzB76-C0c

14. 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.

15. 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).

16. The organisation of a computer

17. 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

18. 43 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

19. 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’

20. 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 http://www.youtube.com/watch?v=UmSelKbP4sc Binary Numbers

21. Digitalisation • 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

22. 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

24. Main components of a typical desktop computer • Motherboard • CPU • RAM • Video Card • Power Supply • Hard Drive • (Optical Drive) • http://www.youtube.com/watch?v=kMRDmkFsUZs&feature=related

25. Logical Parts of Computers • Memory • CPU • Peripherals

26. 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.

27. 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

28. Different types of memory • RAM • ROM • Cache • Dynamic RAM • Static RAM • Flash memory • Memory Sticks • Virtual memory

29. 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.

30. 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).

31. 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.

32. 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. • http://www.youtube.com/watch?v=atWlAdVvTx8&feature=related

33. 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.

34. FurtherMemorycomments • 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:

35. 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.

36. 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.

37. 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.

38. 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.

39. 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.

40. CPU • 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.

41. 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.

42. 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.

43. 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.

44. 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.) http://www.youtube.com/watch?v=qiTt33_3boI&feature=related

45. 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

46. The four most important characteristics of storage devices: • Speed and access time • Cost / Removable versus non-removable • Capacity • Type of access

47. HardDisk 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.

48. Hard Disk Drives and Direct Access

49. 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.

50. 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.