Introduction to Computer

A Computer can be define as an electronic device, made by Hardware and Software. A computer can store data, Mathematical & non Mathematical operations, with high speed and accuracy. We can says that a computer is a device which enters the data as the input then processes the data according to user need and store it in memory or display the result as the output.

 History of computer • In the early period, a manual-calculating device ‘Abacus ’was developed as a counting instrument. • Another these type of machine developed by John Napier in 1617 called Napier’s Bones or Cardboard Multiplication. • French mathematician Blaise Pascal produced a devise “Pascaline“ in 1945. • In 1671, German Mathematician Gottfried Von Leibnitz invented a calculating machine called the Stepped Reckoner. • Charles Babbage of Cambridge University (considered the father of modern or digital computer) developed a machine called Analytical engine in 1833. • Than in early 19th century, Harman Hollerith invented tabulating machine. • Mark-I computer also called the Automatic Sequence Controlled calculator developed in 1937by Howard Aiken, considered as the first fully automatic calculating machine. • ABC (1939-42 by John Atanasoff), ENIAC (1943 by Eckert and Mauchly), EDVAC (1947 by Maurice Wilkes) and next UNIVAC Classification of computer Analog computer is an computer which used analog signals for transmission of process. Analog signals represented as a series of sine waves. Broadcast and phone conventional is the good example of analog technology. Digital computer which transmitted data in digital signals, in the high (on) and low (off) or as 1’s (on) and 0’s(off) voltage state of electricity. In digital technology , the signals that travel can be represented in the term of two states – Positive (1’s) and non-positive(0’s). Hybrid computer those computer which employ both the feature of Digital and Analog computer. Super computer first super computer invented in 1976, called Cray-1. With their advanced characteristics , super computer used in chemical reaction, weather forecasting, nuclear reaction etc. Mainframe computer are coming in the second position according their characteristic after super computer, mostly used in large Industries. Other computer such as Minicomputer, PC, Laptop etc..

Generation of Computers- classified the computer according to What electronic component it used, we have parted in five Generation ,from its 1st to 5th Generation. 1st Generation of Computer (1942-55)-In the first Generation of computer, using Vacuum tube as electronic switching device and Magnetic drum for memory. A Vacuum tube was a fragile glass device that can control and amplify electronic signals. Its big sizes, Heating ,Complex programming and slow speed of processing , the use of computers so complex. Example of some early computer: • MARK 1 • Atanasoft Bery Computer (ABC) • Electronic Numerical Integrator and Calculation(ENIAC) • Electronic Discrete Variable Automatic Computer (EDVAC) • Electronic Delay Storage Auto Calculator(EDSAC) • UNIVAC 1 • IBM-701 & IBM-650 2nd Generation of Computer(1955-64) – In 1947 the three American- John Bardeen, William Shockley and Walter Brattain invented a new electronic switching device at Bell Telephone Laboratories. The advantage of this Generation computers was reduced in size and Heat generation and increased capabilities in processing speed and reliability. High level language such as Fortran, COBOL, ALGOL & SNOBOL was using start in these period. Some example of 2nd Generation Computer : • Honeywell 400 • IBM-7030 • CDC-1604 • UNIACLARC 3rd Generation Computer(1964-75)- kilby and Noyce invented the first Integrated Circuit(ICs). ICs was a technology ,which used in 3rd Generation of computer in the place of transistor . A single ICs has many transistors, resistors and capacitors grow on a single chip of silicon. Small Scale Integration (SSI) and Medium Scale Integration (MSI) ware used in these phase, which contained 10-20 components and 100 components respectively. Computer were used such as • IBM-360/370 • PDP-8 • TDC-316 • Honeywell-6000 series 4th Generation Computer(1975-89)- With the Advancement of technology, Very Large Scale Integration(VLSI) was used in the place of Medium Scale Integration. VLSI circuits having about 5000 transistors and their associate circuits on a single chip. Fourth Generation computer became more powerful, reliable , fast, and made it possible to a microcomputer. High Level languages and different type of Operating System also used in this generation. example of some computers : • IBM PC • Apple ii • TRS-80 • CRAY-1 or CRAY-11 or CRAY-X-MP

Generation of Computer

5th Generation of Computer(1989-Present)- in the fifth generation , Ultra Large Scale Integration(ULSI) are used, as a result Microprocessor having ten million electronic components .some characteristics of fifth generation computer is : • Artificial intelligence • Natural language processing • More user friendly • Intelligence as human being Type of computer in this generation • Desktop • Laptop • Note-Book • Ultra-Book Data flow and process of computer system Input Processing Storing Controlling g Output Input device Input is an device those help us entering data and instruction into the computer. Input device converted human language into computer binary language(1’s and o’s), as well as links between person and computer. Some input devices are: Keyboard, Mouse, Webcam, Joystick or Gamepad, Barcode reader, Pen input or Touch, Scanner, OMR etc. Central Processing Unit(CPU) it is the main part of computer, also Known as the heart of any computer system. All major functions and operations are performed inside the CPU. Next parted in two sub-parts • The Control Unit to manage and coordinate the operations of all other components. It’s obtain instruction from a program stored in the main memory, interprets these instructions and signals to other units to execute them. This Unit works as a supervisor of the computer system. • The Arithmetic Logic Unit(ALU) computer perform all the calculation and comparison in this unit. CPU Instruction Set- Instruction Set is a set of machine instructions. every CPU has built in ability to execute them. Most of the CPU have 200 or more instruction ability. CPU Registers – when CPU unit obtains the instruction from programs ,than interprets them and request to other unit to execute them. To handle these process the CPU uses a number of special memory unit, called Registers. These Registers hold information on temporary basis. Registers also a part of CPU not memory. Listing of some registers: • Memory Address Register (MAR) • Memory Buffer Register (MBR) • Program Control Register (PCR) • Accumulator Register (AR) • Instruction Register (IR) • Input/ Output Register (I/O R) Processor speed- we measure the Processor speed in the following Parameter • Megahertz(MHz) • Gigahertz (GHz) • MIPS (Millions of Instruction per Second) • BIPS (Billions of Instruction per Second) • MFLOPS (Millions of Floating Point Operation per Second) • GFLOPS (Gigaflops) • TFLOPS (Teraflops) Storage Unit which unit store the data called Storage Unit. In computer system consist of two type of memory- Main or primary and secondary memory Primary Memory / Storage- Primary memory also known as the Main memory. Various type of main memories are listed following: • RAM(Random Access memory)- RAM is the Primary Memory and Volatile in nature. In this memory, we can read data as well as editing is also Possible. RAM is the memory, where data is stored on temporary basis while computer is on. RAM are two type I) Static RAM(SRAM) II) Dynamic RAM(DRAM) • ROM(Read Only Memory)- A special type of RAM, called ROM. ROM is non-Volatile in nature, Which data is readable not editable. ROM is used for Permanent Storage, also known as Dead storage or Field storage. ROM has two type: i) PROM- Programmable Read Only Memory(PROM) is a ROM that can be modified only one time, not possible again and again. Programmer used this memory as to store program permanently. For example, a computer maker may store the system Boot Program permanently in a ROM, located on the Motherboard. ii) EPROM- Erasable Programmable Read Only Memory(EPROM) is also a ROM, which Erasable and Reprogrammable ability. EPROM is next two type: - UVEPROM (Ultra Violet EPROM) - EEPROM (Electrically EPROM) • Cache Memory- Cache memory is placed between the CPU and the main memory. It is small in size and fast in nature. Hit Ratio is the parameter to measure the performance of cache memory. Secondary Storage - also known as Auxiliary memory. It is non-volatile memory and Read Only Memory. Parted in two part: i) Sequential Access Devises – In these device, which arrival at a desired Stored Location is Proceeded by Sequencing through other location. Access one location to another is sequential or one by one. For example we want to listen 8th song from a recorded tape, we must listen 1-7 song coming for it. Example of these type of device is Magnetic Tape ii) Direct/Random Access Devices – is device we can reach and access any storage location at equal access time i.e. we want to listen 8th song, selected and listen song. These device are 3 type: - Magnetic Disks - which Floppy disk, Hard disk. - Optical Disks - which CD-ROM, WOROM, DVD, CDRW. - Memory Storage Devices - which Memory card, Flash drive, RAM disk. Units of Memory • 1 byte = 8 bits • 1 Kilobyte (KB) = 1024 bytes • 1 Megabyte(MB) = 1024 KB • 1 Gigabyte(GB) = 1024 MB • 1 Terabyte(TB) = 1024 GB • 1 Petabyte(PB) = 1024 TB • 1 Exabyte(EB) = 1024 PB • 1 Zettabyte(ZB) = 1024 EB • 1 Yottabyte(YB) = 1024 ZB Output device after perform all the process ,computer system produce the result in binary language(1’s and 0’s) and these output device converted it into binary to human readable. LCD, CRT monitor, Plotters, Projector, Speaker, Headphones, Printer etc. Number system in computer We know that computer is an machine and understands only machine language mean binary language(0’s and 1’s), cannot communicate with human in natural language such as English, Hindi etc. so, computer professional uses various type of number system, to understand and communicate with computer machine • Binary Number System in which only two Number are used- (i) 0 and (ii) 1. The base number is 2.binary number system invented by G W V Leibnitz in 17th century. • Octal Number System the base number 8. There are only eight digit & symbol used from 0, 1…… up to 7. • Hexadecimal Number System in this number system ,the base is 16 and use digit 0 to 9 and alphabets from A to F. Alphabets A,B,C,D,E and F representing decimal value 10,11,12,13,14 and 15 respectively. Computer Codes or CCS- Computer Coding Scheme(CCS) also known as Computer Codes. For communication with computer, we have to need introduce some binary codes, those represented by a combination of binary digits. These binary code represented the various human language as well as different symbols. These codes enable easy transfer/exchange of data between computer 1. BCD Code 2. EBCDIC Code 3. ASCII Code 4. UNICODE

Computer Networks: A computer Network can be defined that type of connection which one computer exchange or share information with other computer or group of computer. In the computer network, one node networked with other nodes with communication media, known as Data Link. The connection b/w nodes are established using either Cable media or Wireless media. Intranet and Internet is the best-Known computer networks. Network Criteria and evaluation- Efficient and effective communication, A computer networks should be meet the Following criteria:- • Performance • Reliability • Recovery • Consistency • Security Network Topology – A network is defined as a number of nodes connected with each other by communication links and the Network Topology is a way which one node to connected with other and how they communicate. Network topology can be logical and physical. Different type of topology:- • Bus Topology • Star topology • Ring topology • Hybrid topology • Tree topology • Mesh topology Classification of Network on the basis of Sizes • Local Area Network(LAN) • Wide Area Network(WAN) • Metropolitan Area Network(MAN) Transmission Media or Network Media – Transmission from one node to another, need a some type of wired and unwired connectivity, these wired and unwired media known as transmission media. The most common network for data transmission are following type:-

 Wired transmission media: • 

Twisted Pair • 

Coaxial Cable • 

fiber Optic Cable Wireless Transmission media • 

Radio waves transmission • 

Microwave transmission • 

Infrared transmission • 

Satellite transmission