Introduction To Computers

CHAPTER 1: Introduction to computers

COMPUTER Definition:

Computer is an electronic device which takes through input devices, processes the data into information and provides the result through output devices.

Characteristics of computer:-

1. Automatic
2. Speed
3. Accuracy
4. Diligence
5. Versatility
6. Power of remembering and storing

Drawback:-

1. No I. Q(Intelligence)
2. No feelings, emotions

Evolution of computers:-

• ABACUS was a calculating device and not machine.
• In 1617 John Napier invented a machine called ‘Napier Bones’
• In 1642 Blaise Pascal invented the first mechanical adding machine.
• Charles Babbage is considered the Father of modern Digital computers. Two machines were designed by him.
• In 1822 he designed “difference Engine”
• In1837 he designed “Analytical Engine” for performing basic arithmetic functions.
• Computer first programmer- Ada King, wrote program for the difference Engine, thus becoming the first computer programmer.
• In 1890, Herman Hollerith developed punchcards.
• John Von Neumann, gave the basic computer architectural designing. He also gave the concept of stored program.

Introduction to computers Generations:-

“Generation” in computer language talks about development in technology. It provides a framework for the growth of computer industry. There are five computer generations-

First Generations (1942-1956)

Characteristic feature of first generation computer are as follows:

• Electronic circuitry used vacuum tubes.
• Punch cards used for feeding information.
• Magnetic tapes were used for external storage.
• Development of machine language and assembly language.
• Power-consumption of these computers was very high due to vacuum tubes.
• Typical computer: ENIAC, EDVAC, EDSAC, UNIVAC-1, IBM-650, IBM-701.
• First generation computers are of very large size having slow processing speed and are very expensive due to heavy power consumption.

Second Generation (1956-1965)

Characteristic feature of Second generation computer are as follows:

• Electronic circuitry characterized by the use of transistors.
• The transistors were faster, more reliable, smaller and much cheaper to build than a vacuum tube.
• Computers were more than ten times faster than the first generation computer.
• They were smaller in size and consumed less power and dissipated less heat than first generation computers.
• Introduction of batch operating system enabled multiple jobs to be batched together and submitted at a time.
• Development of high level language like FORTAN, COBOL, ALGOL, SNOBOL etc.
• Typical computer: IBM 1400 series and 7000 series, control data 3600, General Electric 635 and Honeywell 200.

Third Generation (1965-1971)

Characteristic feature of third generation computer are as follows:

• Integrated circuits(IC) were introduced which were microscopic in size, contained the equivalent of many transistors.
• Monitors and key board were introduced for data input and output.
• Magnetic disk used for external storage.
• IC’s were made up of silicon material where transistors were made inbuilt.
• Time sharing operating system was introduced which helped multiple users to use the system simultaneously.
• More high level language including PASCAL, BASIC, RPG, PL/1 etc. were developed.
• Typical computers: IBM system 360, PDP-08,PDP-11,CDC 6600

Fourth generation (1971- till today)

Characteristic feature of fourth generation computer are as follows:

• Development of large scale integration (LSI) and very large scale integration (VLSI) technologies of IC’s.
• Invention of microprocessor computers by IBM in 1980 (personal computer series).
• LAN and WAN concept of networking led to the development of the internet.
• Introduction of microprocessor chip.
• This generation also saw the development of GUI’s (Graphical user interface), the mouse, floppy disk and hand held devices.
• More high level languages like c, c++, Java, etc. were developed.
• Typical computer: IBM PC, Apple II, CRAY- I, CRAY-II, VAX 9000, HP 3000.
• Optical disks like CDs and DVDs were launched

Fifth Generation (FUTURE)

Characteristic feature of fifth generation computer are as follows:

• Fifth generation computing devices based on artificial intelligence (AI) are still in development
• The use of parallel processing and super conductors is helping to make artificial intelligence a reality.
• The goal of fifth-generation computing is to develop devices that respond and act like human being and capable of learning and self-organization.

Important computers

1. MARK-1(1937): It was an electromagnetic device that used thousands of mechanical switches to control its operation.
2. ENIAC (1946): The electronic numerical integrator and CALCULATOR was the first electronic computer.
3. EDVAC (Electronic discrete variable automatic computer) used the stored program concept in its design.
4. UNIVAC-I (1951) : Universal Automatic Computer –I (UNIVAC – I) was the first digital computer.
5. EDSAC (1947): Electronic Delay storage Automatic CALCULATOR (EDSAC)
6. IBM – 701: International Business Machine (IBM) Corporation introduced the IBM -701, its first commercial computer in 1952.

Computer Language

The language acceptable to a computer system is called computer language and process of writing instructions in such a language is called programming or coding.

Computer languages can be classified into three categories-

1. Machine Language (Low Level Language)
2. Assembly Language (Mid-Level Language)
3. High-Level Language

Machine Language

A Computer’s machine language consist of strings of binary number (i.e. 0 and 1) and is the only one which the processor directly understands. Machine language programs have an advantage of very fast execution speeds and efficient use of primary memory. The first computer program was written in machine language.

Assembly Language

It is also considered in low level language along with machine language. It uses mnemonics in place of 0’s and 1’s to represent the operation code. This language contain a contain a system software known as assembler, which translates an assembly language program into its equivalent machine language program.

High-Level Languages:

These are machine independent and do not require programmers to know anything about the internal structure of the computer on which the high-level language programs are executed. These languages use characters, symbols and mathematical notations. These languages are easier to learn, requires less time to write and do not deal with machine-level coding. High level language must also be translated into machine language before they can be used on a computer. There are two different language translator programs used to translate high-level languages-

1. Interpreter: It translates a high-level language program into machine language line by line and executes line of the program after it is translated using RAM only.
2. Compiler: It is also a high-level language translating program which translates the whole program in a single instance or move, in machine language i.e. complete source code at once into machine code and saves the object code also.

Examples of some High level languages being used are:

1. FORTRAN(Formula Translation)
2. COBOL(Common Business Oriented Language)
3. BASIC(Beginners all-purpose symbolic instruction code)
4. ALGOL(Algorithmic Language)
5. PL1(Programming Language One)
6. LISP(List Processor)
7. PROLOG(Programming Logic)
8. PASCAL
9. ADA
10. LOGO
11. C
12. PERL
13. C++
14. JAVA