Fundamental concepts of Information Technology A brief history, the - - PowerPoint PPT Presentation

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

1

A brief history Computer generations

2

The Neumann architecture The Neumann-principles The conceptual architecture of computers

3

The language of computers 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

• perating 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

• ctal (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 1

Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 11 / 17

Logic gates (2)

AND: A B A AND B 1 1 1 1 1

Csernyi G´ abor (DE IEAS) Fundamental concepts of IT 12 / 17

Logic gates (3)

OR: A B A OR B 1 1 1 1 1 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 1 1 1 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 23 + 22 + 21 + 20 = 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 ➔ 26 + 25 + . . . + 20 = 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