HISTORY & EVOLUTION OF COMPUTERS:
The computer may be classified into a number of generations. The classification may be based on:
Generations of Computers Based on Hardware:
First Generation Computers: (1945 -55)
- The computer started with ENIAC.
- 1951: It was then followed by the IBM UNIVACI (Universal Automatic Computer) built by Mauchly & Eckert.
- This machine could perform business data processing.
- Used: Vaccum tubes.
- Because of vacuum tubes, computers were;
- Very large,
- Required lot of energy
- Slow Input/Output
- Suffered from heat & maintenance problems.
- Language: Machine level language or machine language, Binary language.
Second Generation Computers: (1955 -65)
- The Transistors were used in second-gen. computers- to overcome the difficulties faced in the first generations due to the use of vacuum tubes.
- Transistor: It is a small component made of semiconductor devices.
- Benefits after use of transistors;
- the problems of heat were minimized.
- The computer size was reduced.
- Storage capacity - improved.
- Machine language is replaced by higher-level languages: ALGOL, FORMAN.
- Example of second-gen. computers: IBM 1620.
Third Generation Computers: (1965 -80)
- The transistor is replaced by Integrated Circuits (IC).
- These circuits are fixed on the silicon chip.
- The silicon chip consumes less than 1/8th of an inch square on which 10 computer studies: 9 many electronic components like diodes, transistors, capacitors, etc. can be fixed.
- The wire interconnections about the components of the circuit are minimized.
- These computers were: smaller, faster & more flexible in terms of Input/Output.
- It also satisfied the need for small business & computers became popular as "Minicomputers".
- Language: C, COBOL, JAVA.
- Example of third-gen. computers: IBM 360, PDP8, PDP11.
Fourth Generation Computers: (1980 -89)
- The computer used large scale IC called VLSI (Very Large Scale Integration)
- Because of VLSI, computers were: faster, smaller, reliable.
- It soon evolved as interactive general-purpose machines that allow rapid application development.
- It became more user-friendly & can be used widely for personal applications. Hence, it is called- "Personal Computers" (PC).
- These computers can process billions of instruction/sec.
- They are used for applications that require intensive numerical computations such as stock analysis, weather forecasting & other similar complex applications.
- Language: SQL (Structured Query Language)
- Example of fourth-gen. computers: IBM PC, Apple II, Supercomputer CRAY.
Fifth Generation Computer: (1989 -till)
- The computers made smarter in terms of processing speed, user-friendliness & connectivity to the network.
- These computers are portable & sophisticated.
- The key features of the computers: Powerful desktops, notebooks, variety of storage mechanisms such as optical disks & advanced software technology such as OS & AI.
- The languages are designed to make the computer solve as a given problem without the programmer. Example; voice recognition & intrusion detection. It uses AI techniques to meet their goal.
- Artificial Intelligence (AI): can handle imprecision & supports human-like self-learning & problem-solving.
- Example of fifth-gen. computers: IBM notebooks, Param 10000, Pentium PC.
Generations of Computer-Based on Software:
- Software plays a vital role in computer systems by creating a bridge between computer hardware & computer user.
- It can be considered as "Soul of Computer", without which the computer can't work.
- Software is an organized collection of data & instructions given to computers in order to perform a given task. These components are data, instructions & documents about the software such as comments.
- Program: The set of instructions.
- Programming: The process of writing or coding.
- Programmers: An individual who performs the programming or coding task.
There are two major types of software:
System Software:
- It manages computer hardware & acts as an interface between computer hardware & software developed for business applications.
- It provides functionalities like;
- Booting computers properly,
- Managing memory,
- Channeling data from secondary memory to primary memory,
- Example of system software: Operating system, Translator program.
- Compiler: Some translator programs transform the whole source code written in a programming language (the source language) into another computer language- target language, binary language. Later the translated code is computed to the desired results.
- Interpreters: Some translators program transform the source code into the target code in line by line fashion & produce the result at the same time.
- Since interpreters try to convert the source program line by line, they can concentrate on a single line, hence it is not possible to analyze the source code.
- Compliers are fast in comparison to interpreters.
Application Software:
- It is a set of computer instructions that provide specific functions to users.
- These functionalities may be general-purpose like- word processing or maybe very narrow, such as an organization's payroll program that generates pay-slips in the company's format, on the company's preprinted stationery.
- It also supports business applications like printing reports from data stored, calculating bills, generating pay-slips, marking attendance, printing students' mark-sheets, etc.
- Special software needs to be developed for this type of application support.