1: History, Generation & Classification. Shobhanjana Kalita, Dept. of CSE, Tezpur University

Transcription

1 1: History, Generation & Classification Shobhanjana Kalita, Dept. of CSE, Tezpur University

2 History Computer originally (17 th century) meant someone who computes Only in the 20 th century it was associated with programmable devices that can automatically perform computations The Pre - Mechanical Era Started with the need to count Early humans used simple mechanisms to help them count Fingers, Pebbles, marks on walls etc

3 History The Mechanical Era Early 17 th century to mid 20 th century Abacus for additions, subtractions Mathematicians designed and implemented devices to do tedious computations Napier s bones (to compute logarithms), Shickhard s Slide rule (for multiplications, divisions) etc Charles Babbage s Difference Engine & Analytical Engine

4 History Mechanical Era Charles Babbage father of computer His Difference Engine & Analytical Engine led to the invention of modern computers First incorporated the idea of Programming Programs were written in binary and given to the computers in the form of punched cards Lady Ada Augusta helped in writing programs for his machines first computer programmer

5 History Electro Mechanical Computers Herman Hollerith s Census Tabulating Machine, Mark 1 etc. Electricity was used to power these machines Used Mechanical relays (switches) which flip flopped back and forth to represent mathematical data Discovery of the first bug by Dr. Grace Hopper (COBOL)

6 History & Generation First Generation Electronic Computers ( ) Used electronic switches made of vacuum tubes Atanasoff (to solve partial differential equations), Alan Turing (Colossus to crack codes of the German Enigma machine) built electronic non-programmable machines ENIAC (Electronic Numerical Integrator and Computer) first electronic programmable machine John Eckhert & John Mauchly Programmed manually EDVAC John von Neumann Stored Program concept

7 History & Generation Second Generation Computers ( ) Electronic switches were made of diode and transistor technology faster & smaller High level Programming language FORTRAN, ALGOL, COBOL Third Generation Computers ( ) Use of Integrated Circuit semiconductor devices (several transistors on one component) complex processors Introduction of operating systems Faster solid state memory

8 History & Generation Fourth Generation Computers ( ) Large scale integration (LSI devices per chip) and very large scale integration (VLSI - 100,000 devices per chip) were used Semi-conductor memories Very high level programming language FP and Prolog Fifth Generation ( ) Machines with hundreds of processors that could all be working on different parts of a single program Computer networks (WAN, LAN) Single-user workstations Parallel Processing

9 History & Generation Sixth Generation Computers (1990 ) No fundamental changes improvements over established systems Micro-controller technology embedded systems Small computers inside devices to control features or actions of Small computers inside devices to control features or actions of the product to make them automated, user-friendly

10 Classification Based on data handling Analog Computers Employs continuous physical phenomenon (electrical, mechanical etc.) values to represent data/quantities Difficult to maintain accuracy of data Digital Computers Operates on data/quantities represented as binary digits (bits) More accurate results, faster Hybrid Computers Capable dealing with both digital and analog signals

11 Classification Based on Size Microcomputers Computers for personal use desktops, game consoles, mobile devices Minicomputers Midrange computers larger than PCs, smaller than mainframes Multiuser computers Mainframe computers Traditional large, institutional computers to service multiple users from smaller single user machines usually used as servers Capable of handling large amounts data Super computers Focused on performing intense numerical, complex scientific computations Most powerful in terms of processing power, memory capacity, speed, I/O technology

12 Classification Based on Function Server Computer dedicated to providing a service database servers, file servers, web servers Workstation Computer intended to serve one user Contains special hardware enhancements for technical and scientific applications high performance CPU, graphics for complex mechanical design or engineering simulation Information appliances Computers designed for regular user-friendly functions playing music, photography, text editing Embedded computers Computers that are part of some machine or device automobiles, washing machines, music players. Operate continuously, software cannot be modified

13 Organization

14 Organization Input Unit To provide the data and instruction to perform a task Keyboard, mouse, CD drive Accept data and converts to machine understandable form Storage Unit Holds data and instructions that are entered through the input unit, before they are processed; Stores results before these are sent to the output devices Primary Storage: Used to hold the program being currently executed, the data received from the input unit, the intermediate and final results of the program; very fast, temporary Secondary Storage: Stores programs and data for future use; archived data

15 Organization Output Unit Provides information and results to output Monitor, printers, hard disks Central Processing Unit Arithmetic and Logical Unit (ALU): Does all arithmetic (+,- Arithmetic and Logical Unit (ALU): Does all arithmetic (+,-, *,/ etc) and logical (>, <, = etc) operations within the computer. Control Unit: Controls all other units within the computer Controls flow of data from storage to ALU, synchronizes the working of all units