8d ago

14 Views

0 Downloads

263.54 KB

21 Pages

Transcription

Fundamental concepts of Information TechnologyA brief history, the Neumann architecture, the language of computersCsernyi GáborDepartment of English LinguisticsUniversity of DebrecenCsernyi Gábor (DE IEAS)Fundamental concepts of IT1 / 17

Table of contents1A brief historyComputer generations2The Neumann architectureThe Neumann-principlesThe conceptual architecture of computers3The language of computersRepresenting numbersLogic gatesRepresenting textCsernyi Gábor (DE IEAS)Fundamental concepts of IT2 / 17

A short history: computer generations (1)First generation ( 1946-54):development of the vacuum tube: Lee de Forest (1906)Presper Eckert and John Mauchly, together with Neumann János andHermann Goldstine: ENIAC machine (Neumann’s importance!)Neumann & Goldstine: the formulation of the requirements of theelectronic digital computer Ô the (von-)Neumann principlesstorage: punch card, tapehuge computers with high energy consumption, air conditionersneeded to reduce heat produced by computerswarm-up timeelectric failureslower-level programming, machine languageCsernyi Gábor (DE IEAS)Fundamental concepts of IT3 / 17

A short history: computer generations (2)Second generation ( 1955-64):invention of transistor: Walter Brattain, John Bardeen & WilliamShockley (1947)compared to the vacuum tube:Iless energy consumption, less heatIsmaller but fasterIhigher reliabilityIno warm-up timestorage devices: removable disk, magnetic tapethe development of the first high-level programming language:FORTRANCsernyi Gábor (DE IEAS)Fundamental concepts of IT4 / 17

A short history: computer generations (3)Third generation ( 1965-74):development of IC (integrated circuit): Jack Kilby & Robert Noyce(1959)electronic circuit on silicon chipmagnetic core memory replaced by microchipoperating systemskeyboard, screenmass productionIntel (INTegated ELectronics) (1968)small-scale integration (SSI), medium-scale integration (MSI)Gordon Moore’s prediction (that the number of transistors on anintegrated chip will double every year (1965)) still holdsCsernyi Gábor (DE IEAS)Fundamental concepts of IT5 / 17

A short history: computer generations (4)Fourth generation ( el processingfirst IBM PCs (1981) and Apple computers (1983)graphical user interface (GUI)small and faster integrated circuitshigher capacity memory typeslarge-scale integration (LSI)Csernyi Gábor (DE IEAS)Fundamental concepts of IT6 / 17

A short history: computer generations (5)Fifth generation ( mid-1990s-):artificial intelligence, problem solvingexpert systemsroboticsnatural languageCsernyi Gábor (DE IEAS)Fundamental concepts of IT7 / 17

The Neumann-principles1Executing the instructions sequentially.also note: multiprocessor computersCsernyi Gábor (DE IEAS)Fundamental concepts of IT8 / 17

The Neumann-principles1Executing the instructions sequentially.also note: multiprocessor computers2Completely electronic computer, using the binary system.lower voltage: 0; higher voltage: 1Csernyi Gábor (DE IEAS)Fundamental concepts of IT8 / 17

The Neumann-principles1Executing the instructions sequentially.also note: multiprocessor computers2Completely electronic computer, using the binary system.lower voltage: 0; higher voltage: 13Internal memory.Csernyi Gábor (DE IEAS)Fundamental concepts of IT8 / 17

The Neumann-principles1Executing the instructions sequentially.also note: multiprocessor computers2Completely electronic computer, using the binary system.lower voltage: 0; higher voltage: 13Internal memory.4Program is stored in the (same) memory as data: the computer is astored program machine.Csernyi Gábor (DE IEAS)Fundamental concepts of IT8 / 17

The Neumann-principles1Executing the instructions sequentially.also note: multiprocessor computers2Completely electronic computer, using the binary system.lower voltage: 0; higher voltage: 13Internal memory.4Program is stored in the (same) memory as data: the computer is astored program machine.5Universal computer.Csernyi Gábor (DE IEAS)Fundamental concepts of IT8 / 17

The conceptual architecture of computersCsernyi Gábor (DE IEAS)Fundamental concepts of IT9 / 17

Representing dataNumber systems:ternary (base 4) digits: 0-3octal (base 8) digits: 0-7decimal (base 10) digits: 0-9hexadecimal (base 16) digits: 0-9, A-FNeumann principles Ô computers use the binary number system.practiceRepresentatoin, conversion from one number system to another, basicmathematical operations (adding, multiplying).Csernyi Gábor (DE IEAS)Fundamental concepts of IT10 / 17

Logic gates (1)Statements: true / false1: true0: falseNOT:A10Csernyi Gábor (DE IEAS)NOT A01Fundamental concepts of IT11 / 17

Logic gates (2)AND:A1100Csernyi Gábor (DE IEAS)B0101A AND B0100Fundamental concepts of IT12 / 17

Logic gates (3)OR:A1100Csernyi Gábor (DE IEAS)B0101A OR B1101Fundamental concepts of IT13 / 17

Logic gates (4)XOR (exclusive OR):A1100Csernyi Gábor (DE IEAS)B0101A XOR B1001Fundamental concepts of IT14 / 17

Representing text (1)1BCD (Binary Coded Decimal)4 bits for each decimal (3 bits would not be enough; the maximumnumber that can be represented with 4 bits is23 22 21 20 15)e.g.: 127 00011Csernyi Gábor (DE IEAS)0010201117Fundamental concepts of IT15 / 17

Representing text (2)2EBCDIC (Extended Binary Coded Decimal Interchange Code)the extension of BCD: additional four bits, the first four called thezone (which group the character is in), the second four called thedigit (the code of the character)Csernyi Gábor (DE IEAS)Fundamental concepts of IT16 / 17

Representing text (3)3ASCII (American Standard Code for Information Interchange)Ithe original version used 7 bits for representation: to code numbers,control characters (e.g.: return), and letters of the English alphabetmaximum of 127 characters can be represented( 7 bits Ô 26 25 . . . 20 127)Ilater extended: 8 bits used for representation, to code letters notincluded in the English alphabet ( 128 characters can be coded) thisadditional bit is used for defining code pages problematic issue: inconsistency (two different characters with thesame code in two different code pages) solution: UNICODEFnumber of bits used for representation: 16 (65536 characters can berepresented!), then extended to 32Fadvantage: no code pages, consistent among languagesCsernyi Gábor (DE IEAS)Fundamental concepts of IT17 / 17

Neumann principles Ô computers use the binary number system. practice Representatoin, conversion from one number system to another, basic mathematical operations (adding, multiplying). Csernyi G abor (DE