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Fundamental concepts of Information Technology A brief history, the Neumann architecture, the language of computers Csernyi G´ abor Department of English Linguistics University of Debrecen Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 1 / 17

Table of contents A brief history 1 Computer generations The Neumann architecture 2 The Neumann-principles The conceptual architecture of computers The language of computers 3 Representing numbers Logic gates Representing text Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 2 / 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 J´ anos and Hermann Goldstine: ENIAC machine (Neumann’s importance!) Neumann & Goldstine: the formulation of the requirements of the electronic digital computer ➔ the (von-)Neumann principles storage: punch card, tape huge computers with high energy consumption, air conditioners needed to reduce heat produced by computers warm-up time electric failures lower-level programming, machine language Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 3 / 17

A short history: computer generations (2) Second generation ( ∼ 1955-64): invention of transistor: Walter Brattain, John Bardeen & William Shockley (1947) compared to the vacuum tube: ◮ less energy consumption, less heat ◮ smaller but faster ◮ higher reliability ◮ no warm-up time storage devices: removable disk, magnetic tape the development of the first high-level programming language: FORTRAN Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 4 / 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 chip magnetic core memory replaced by microchip operating systems keyboard, screen mass production Intel (INTegated ELectronics) (1968) small-scale integration (SSI), medium-scale integration (MSI) Gordon Moore’s prediction (that the number of transistors on an integrated chip will double every year (1965)) still holds Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 5 / 17

A short history: computer generations (4) Fourth generation ( ∼ 1974- mid-1990s ): nanotechnology microprocessor parallel processing first IBM PCs (1981) and Apple computers (1983) graphical user interface (GUI) small and faster integrated circuits higher capacity memory types large-scale integration (LSI) Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 6 / 17

A short history: computer generations (5) Fifth generation ( ∼ mid-1990s -): artificial intelligence, problem solving expert systems robotics natural language Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 7 / 17

The Neumann-principles 1 Executing the instructions sequentially. also note: multiprocessor computers Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 8 / 17

The Neumann-principles 1 Executing the instructions sequentially. also note: multiprocessor computers 2 Completely electronic computer, using the binary system. lower voltage: 0; higher voltage: 1 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 8 / 17

The Neumann-principles 1 Executing the instructions sequentially. also note: multiprocessor computers 2 Completely electronic computer, using the binary system. lower voltage: 0; higher voltage: 1 3 Internal memory. Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 8 / 17

The Neumann-principles 1 Executing the instructions sequentially. also note: multiprocessor computers 2 Completely electronic computer, using the binary system. lower voltage: 0; higher voltage: 1 3 Internal memory. 4 Program is stored in the (same) memory as data: the computer is a stored program machine. Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 8 / 17

The Neumann-principles 1 Executing the instructions sequentially. also note: multiprocessor computers 2 Completely electronic computer, using the binary system. lower voltage: 0; higher voltage: 1 3 Internal memory. 4 Program is stored in the (same) memory as data: the computer is a stored program machine. 5 Universal computer. Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 8 / 17

The conceptual architecture of computers Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 9 / 17

Representing data Number systems: ternary (base 4) digits: 0-3 octal (base 8) digits: 0-7 decimal (base 10) digits: 0-9 hexadecimal (base 16) digits: 0-9, A-F Neumann principles ➔ computers use the binary number system. practice Representatoin, conversion from one number system to another, basic mathematical operations (adding, multiplying). Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 10 / 17

Logic gates (1) Statements: true / false 1: true 0: false NOT: A NOT A 1 0 0 1 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 11 / 17

Logic gates (2) AND: A B A AND B 1 0 0 1 1 1 0 0 0 0 1 0 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 12 / 17

Logic gates (3) OR: A B A OR B 1 0 1 1 1 1 0 0 0 0 1 1 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 13 / 17

Logic gates (4) XOR (exclusive OR): A B A XOR B 1 0 1 1 1 0 0 0 0 0 1 1 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 14 / 17

Representing text (1) 1 BCD (Binary Coded Decimal) 4 bits for each decimal (3 bits would not be enough; the maximum number that can be represented with 4 bits is 2 3 + 2 2 + 2 1 + 2 0 = 15) e.g.: 127 = 0001 0010 0111 1 2 7 Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 15 / 17

Representing text (2) 2 EBCDIC (Extended Binary Coded Decimal Interchange Code) the extension of BCD: additional four bits, the first four called the zone (which group the character is in), the second four called the digit (the code of the character) Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 16 / 17

Representing text (3) 3 ASCII (American Standard Code for Information Interchange) ◮ the original version used 7 bits for representation: to code numbers, control characters (e.g.: return), and letters of the English alphabet maximum of 127 characters can be represented (=7 bits ➔ 2 6 + 2 5 + . . . + 2 0 = 127) ◮ later extended: 8 bits used for representation, to code letters not included in the English alphabet (+128 characters can be coded) this additional bit is used for defining code pages ☞ problematic issue: inconsistency (two different characters with the same code in two different code pages) ☞ solution: UNICODE ⋆ number of bits used for representation: 16 (65536 characters can be represented!), then extended to 32 ⋆ advantage: no code pages, consistent among languages Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 17 / 17