Introduction to Computers

Introduction to Computers

• A computer is an electronic device.
• It takes raw data, processes it into meaningful information, and produces output for use.
• Modern computer systems contain software and hardware components.
• Software components consist of firmware, operating system (OS) software, device drivers, and application software.
• Hardware components consist of a Central Processing Unit (CPU), Data Storage, Input devices, and Output devices.
• Software and hardware components form modern computers for everyday activities.

History of Computers

• The history of computers can be traced to the 19th century, when Charles Babbage designed the 'Analytic Engine'.
• Babbage's design laid the foundation for modern computers.
• The history of computers is divided into five major generations.

First Generation (1937 – 1946)

• First-gen computers used vacuum tubes.
• The first machine was invented by J P Eckert and J W Mauchy between 1943 and 1945.
• The Electronic Numerical Integrator and Computer (ENIAC) was a huge machine.
• ENIAC was developed in Pennsylvania, USA.
• ENIAC had over 20,000 vacuum tubes, 70,000 resistors, and 10,000 capacitors.
• The machine weighed about 30 tons.
• Powering it up caused a noticeable dip in power in surrounding areas.

Second Generation (1947 – 1962)

• Second-generation computers used transistor technology.
• The Universal Automatic Computer (UNIVAC 1) was the first commercial computer.
• UNIVAC 1 launched in 1951 with transistor technology.
• IBM launched the 650 and 700 series computers in 1953.
• Computer programming languages emerged in the marketplace.
• Assembly languages were used in this era.

Third Generation (1963 – 1971)

• Third-generation computers used integrated circuits (ICs).
• Silicon miniaturized sizes of transistors and ICs.
• Integrated circuits were built for electronic circuitries.
• Keyboards and new operating systems replaced punched cards.
• Computers could run more than one application simultaneously.
• Examples of third-generation computers were IBM 360 & 370, and DPD 11.

Fourth Generation (1971 – 2010)

• Fourth-generation computers used Very Large Scale Integration (VLSI) microprocessors and became very popular.
• Many new computer companies and manufacturers emerged.
• Different operating systems and technologies were introduced.
• Personal computers, laptops, and PDAs were introduced.
• Windows, Linux, UNIX, Solaris, and Macintosh operating systems were introduced.

Fifth Generation (2010 – Present)

• Fifth-generation computers are powered by Artificial Intelligence (AI), Ultra Large Scale Integration (ULSI) and robotic processes.
• AI influence began long before 2010.
• The higher level of influence started in the present decade.
• New computers are IBM Watson, multi-core processing machines, distributed processing machines, the latest AI-enabled mobiles, and tablets.

Components of Modern Computers

• Computer machines evolved from the first to the fifth generation..
• This happened through changes in software and hardware components.
• Modern computer devices are used daily across homes and industries.
• Main components are input devices, output devices, Central Processing Unit (CPU), Storage Components and Software Components

Input Devices

• Input devices insert raw data into a computer in different formats.
• Major input devices are keyboards, microphones, barcode readers, cameras, electronic pens, joysticks, MIDI ports, pointing devices, gamepads, touch screens, wireless antennas, USB ports, scanners, and motion sensors.

Output Devices

• Output devices produce meaningful information processed from raw data inputted through input devices.
• Major output devices are monitors, printers, speakers, COM, projectors, plotters, and wireless cards.

Central Processing Unit (CPU)

• The CPU controls the functions of the computer.
• The CPU takes raw data from input devices, processes it, and sends it to output devices or data storage.
• Main components: Arithmetic Logic Control (ALU), Random Access Memory (RAM), Read Only Memory (ROM), and Control Unit (CU).

Storage Components

• Storage components are data storage banks to keep data safe.
• Data is saved on the secondary location, where the data can be easily accessed, and managed.
• Storage components are Hard Disk Drives (HDD), Flash Disk Drives (FDD), Optical Disk Drives (ODD), and Magnetic Tapes.

Software Components

• A computer combines hardware and software.
• Hardware components are ineffective without a computer's software components.
• Major components are operating system software, component drivers, application software, utility software, and, firmware.
• Many software tools and applications are available.
• These software tools facilitate several tasks on modern computer systems.

Future Machines

• Computer science advances faster than other technologies.
• Computer technology impacted other technologies and business processes.
• This rapid growth makes it unpredictable.
• Information Technology (IT) is the fastest-changing technological sector.
• The future of computers is governed by Artificial Intelligence, Quantum Computing, Nanotechnology, and Parallel Processing.

Artificial Intelligence

• AI impacts computing significantly for some time.
• Augmented/Virtual Reality (AR/VR), voice recognition, text interpretation, image processing, motion detection, and others make computers efficient.

Quantum Computing

• Quantum computing is not new, but in its early stages.
• High-level quantum information processing is incomplete.
• Small-scale quantum information processing projects are successful.
• Existing binary processing is heavily impacted with quantum information processing.

Nanotechnology

• Hardware size in electronics and computer technology is decreasing exponentially.
• Early data storage with 18,000 vacuum tubes needed 1,800 square feet and stored up to 18,000 bits of data.
• One vacuum tube stored one bit of data.
• Hardware size has reduced thousands of times.
• A small flash drive stores billions of bytes.
• Electronic hardware sizes are projected to decrease.
• Nanotechnology handles matter at the 100th part of a nanometer level.
• Nanotechnology and quantum physics will likely partner in future computers and revolutionize modern computers.

Parallel Processing

• Parallel processing coordinates multiple components for computer processing.
• Distribution of computer processing increases a computer's processing power.
• Virtualization, cloud computing, and distributed processing systems exemplify parallel processing.
• Implementation of large-scale parallel processing will likely be transformative.

Introduction to Computer Networks

• A computer network connects two or more computers.
• The machines share resources, establish communication, and exchange data electronically.
• The devices or computers are known as hosts.
• A computer network consists of networking devices, computer hosts, wired/wireless media, connectors, and software protocols.
• Configurations known as network topologies connect computers.
• Computers connect via wired or wireless media.
• Media connectors help those connections.
• Communication protocols govern the hardware configuration.
• Communication topologies, protocols, and network types exist.

Network Topologies

• Network topology connects a computer into the network.
• These topologies are references used for network connectivity.
• Star, bus, ring, mesh, and tree network topologies exist.

Major Network Protocols

• Computer network communication takes place through network protocols.
• Digital communication is based on request and response interactions.
• Combination of communication protocols is called network communication protocol.
• Many network protocols exist for communication.
• Communication between two nodes is usually based on client and server model.
• Other communication principles are present.
• Prominent network protocols are Ethernet, TCP/SPX, and IP.
• OSI layer is used for physical and data link protocol.
• HTTP/FTP is used for the upper OSI layers.
• And DNS, SMTP are also used for the upper OSI layers.

Elements of Computer Network

• Basic elements are hosts, connecting media, and connectors.
• Modern networks use hosts, routers, switches, hubs, firewalls, servers, cables/links, protocols, and connectors.

Types of Networks

• Classified into three major types irrespective of connecting media – wireless or wired.
• Types are Local Area Network (LAN), Metropolitan Area Network (MAN), and Wide Area Network (WAN).
• Networks are classified based on coverage area.
• The networks can be wired, wireless, or a combination.

The Internet Explored

• The Internet is a global network of networks.
• It uses the IP address of any node on the internet.
• The TCP/IP protocol is used for data transmission.
• The Internet offers multiple communication services.
• Services are voice and video calls, chats, fax, emails, social media, instant messaging, financial services, bill payments, online shopping, web conferencing, TV streaming, live movies, gaming, file sharing, data transfers, eBanking, data storage, e-marketing, remote healthcare and remote working.
• Internet use revolutionized modern life and activity across business, social interactions, and the public.
• Online use replaced traditional communication.
• More than 4.1 billion people use the internet and almost 2 billion Web sites existed in 2018.
• $4.5 trillion in retail eCommerce sales took place by 2021.
• Huge savings result from the internet in communication and data processing.
• Internet usage is associated with challenges.
• Challenges include security, privacy, and data integrity.

History and Evolution of Internet

• Internet history dates back to Sputnik's launch on October 4, 1957.
• Sputnik was the first satellite launched by the Soviet Union.
• The US government responded by forming Advanced Research Projects Agency (ARPA) on February 7, 1958.
• ARPA was renamed Defense Advanced Research Projects Agency (DARPA).
• The objective was to research how an advanced network would function in a war.
• JCR Licklider of ARPA announced in 1962 that a US computer network can continue to function during a nuclear attack.
• The network was known as ARPA NET.
• Leonard Kleinrock enunciated the packet switching theory in a 1961 MIT publication and a 1964 book on packet switching.
• The packet data switching network started by 1965.
• The packet switching theory was the foundation for current internet communication.
• The interface message processor (IMP) was developed in 1969.
• IMP was the initial version of the router and was able to make data transmission efficient.
• Stanford University's local area network was expanded to connect with the National Science Foundation (NSF) in 1981.
• The network was named NSFNET in 1983.
• The transmission control protocol (TCP) was developed in 1983.
• In 1985 the restrictions on the NSFNET were reduced.
• Multiple US universities participated in the research and communication network.
• Universities and institutes joined the NSFNET.
• The NSFNET became the backbone network.
• The Hypertext Transfer Protocol (Http) was developed by Tim Berners and Lee in 1989.
• Mosaic was the first Internet browser created in 1993.
• Commercial use of the internet was approved in 1993.
• NSFNET was discontinued in 1995.
• The internet was initially used for sharing and peer-to-peer communication.
• The World Wide Web (www) launched in 1995 and changed the shape and power of the internet.
• Improvements were made in speed, security, and other areas.

The Internet in Today’s World

• The Internet’s impact on modern lives is great.
• Nearly every activity across all aspect of life has been influenced.
• The average Internet penetration was 55.1% in 2018. The impact of the internet is enormous across modern life.
• It evolved from a communication tool to hosting Web sites, web applications, mobile applications and cloud computing

Areas revolutionized by Internet

• Telecommunication
• Retail Sales
• Education
• Business Processes

Telecommunication

• Traditional communications were circuit switching landlines, fax, telegraph, and handwriting.
• Traditional methods were expensive and time consuming.
• Internet applications almost replaced all modern use of communication.
• Landlines are switched to IP phones, video calls, and emails.
• Instant messaging, live streaming, chats, and recorded messages added to communication.

Retail Sales

• Traditional retail is increasingly exchanged for online stores.
• The retail sales became a multi-trillion dollar industry due to online shopping.
• Mobile e-commerce is expected to spur even greater growth in the near future.

Education

• There has been a surge in online learning, remote learning, and eLearning.
• Online courses are available from universities across the world.
• Universities were heavily influenced by electronic books, E-libraries, multimedia, and others.

Business Processes

• Internet use greatly improved many business processes.
• Digital marketing, eCommerce, mCommerce, CRM, BPO, automated billing/invoicing, ERP, remote hiring, enterprise application integration (EAI), and business intelligence (BI) have emerged in the business sector.

Other Sectors

• Financing, Banking, Insurance, Healthcare, R&D, Marketing, Tourism, Entertainment, and Gaming

Elements of the Internet

• Uses backbone connectivity and routers to connect individual networks.
• Hardware elements are Internet Cloud, Edge Router, Core Router, Firewalls, Switches, Hubs, Servers, Connectivity and Hosts.

Internet Cloud

• The internet cloud is infrastructure of the internet.
• The consists of small networks like pieces of regular clouds.
• Data is uploaded, downloaded, and saved in the cloud.

Edge Router

• The edge router is the first bridge between the internet cloud and a user's network.
• It maintains global routes and addresses.
• The router distributes packets to other networks.
• Edge routers handle a large amount of details about addresses and routes.

Core Router

• It has information for the entire network is known as a central router.
• External packets are handed to the edge router for distribution.
• The central component distributes data in a single network or corporate network.
• Cisco is one of the leading routers and network element manufacturing company.

Firewalls

• Firewalls are corporate network defense walls.
• They are inside the local network after the edge router.
• Its purpose is to protects malicious intrusion of unauthorized users.
• The latest series of Cisco firewalls is the Firepower 9000 series.
• Threat level firepower firewalls handle approximately 225 Gbps.
• Firewalls prevent cybercrime and possible dangers.

Switches

• Switches isolate the data packets and smaller business units.
• Layer 3 capabilities to distribute data in sub-networks are available.
• They distribute packets at the data link layer based on MAC addresses.
• Top manufacturers of layer switches are Cisco, Juniper, and Teledata.

Hubs

• Hubs broadcast packets within a small local network.
• Hubs have almost vanished nowadays.

Servers

• Heavy computers are configured to handle requests from the network or external networks
• Common types are DNS, voice, media, web, FTP, HTTP, file, proxy, application, IRC, chat, mail, database, and game servers.

Connectivity

• All kinds of things connect to the network over media, topologies, and strategies.
• Hotspots tend to connect at local level via wireless routers.
• Gigabit Ethernet copper or fiber cables are used to link edge routers to routers.
• The connection from the edge router to the backbone has a certain volume of bandwidth.
• Fiber or satellite links usually connect edge routers to the backbone.
• Undersea fiber cables or satellite links are the core of the global internet connection.

Hosts

• Hosts use internet services as terminals.
• It can be computers, mobiles, tablets, watches, printers, and faxes.
• Hosts access client applications.
• Client software tools can be installed to be able to access the server.
• Other forms of communication are Peer to Peer relationships.

Internet Software Infrastructure & Protocols

• Every piece of internet hardware uses unique software.
• Software helps perform desired tasks for particular devices.
• Routers have OS to perform calculations, filters, and routing.
• Switches have system software for their own roles.
• Servers have software to take on a client from within and beyond the network.
• Different servers have different OSes as well as application software that runs from that.

Key Software Infrastructures

• IP Address
• DNS Server
• TCP/IP Protocol
• HTTP Protocol
• WWW

IP Address

• The Internet Protocol (IP) is used in routing.
• It is a 32 bits of binary digits with zeros and ones.
• IP addresses are written in dotted notations.
• Every node has a unique IP address.
• The dotted notation is converted to a dotted decimal like 123.123.123.123.
• Two versions of IP address exists- IPv4 and IPv6.
• IPv4 is extensively used in the internet.
• The IPv6 version is introduced to extend the amount of addresses.
• The IPv4 addresses are divided into many classes and designated for usages.

IPv4 Classifications

• Class A covers 1.0.0.1 to 126.255.255.254 and supports 16 million hosts on 127 networks.
• Class B covers 128.1.0.1 to 191.255.255.254 and supports 65,000 hosts on 16,000 networks.
• Class C covers 192.0.1.1 to 223.255.254.254 and supports 254 hosts on 2 million networks.
• Class D covers 224.0.0.0 to 239.255.255.255 is reserved for multicasting.
• Class E covers 240.0.0.0 to 254.255.255.254 and is reserved for R&D.
• The IPv6 offers more than IPv4.
• Total number of IPv6 will be (2128), equal to 340,282,366,920,938,463,463,374,607,431,768,211,456.
• Globally - The addresses are managed and governed by the International Assigned Number Authority (IANA).

Regional Registries for Regional IP Distribution

• APNIC (Asia Pacific Network Information Center) covers Asia Pacific.
• AFRINIC (Africa Network Information Center) covers Africa.
• ARIN (American Registry covers North America and a few Caribbean countries for Internet Numbers).
• LACNIC covers Latin America.
• RIPE NCC covers Europe, Central Asia, and the Middle East.

Domain Name System (DNS) Server

• Handles conversion of website domain into IP addresses.
• Names are identified, but data transmission requires IP addresses.
• The IP address is sent to DNS server that delivers correct IP of the domain.
• The routing of data packets is performed through IP addresses.
• Users cannot remember many IP addresses.
• Users type URLs in the browser.
• DNS converts domain name to IP.
• After which, that data is sent through IPs that are normally not shown.
• All activities occur between hosts, routers, and DNS servers.
• Hundreds of DNS servers are worldwide, linking with the 13 root servers.
• The 13 root servers are in the USA, Stockholm, Tokyo, and Amsterdam.
• DNS servers are named A through M.
• Other public servers are Google DNS, CloudFlare, and Verizon.
• Such servers are primary or secondary domain servers.

TCP/IP Protocol

• Internetworking protocol(IP) and transport control protocol(TCP) route data across networks.
• Used for the middle layer of OSI model.
• Any network to use internet needs TCP/IP protocol.
• User Datagram (UDP) is another parallel protocol with TCP for certain applications.
• UDP improves performance, although it sacrifices error correction.
• TCP is connection oriented protocol.
• TCP has error checking as well as accuracy.
• UDP improves data transmission and speed in real time applications.
• The data packet is wrapped with headers and the IP and is handed to the TCP or UDP protocol to add its header for going from transmission.
• The reverse process returns the data for the destination.

HTTP Protocol

• Hypertext transfer protocol (HTTP) is a client data communication protocol.
• HTTP accesses a user which use web browsers, mobile apps, voice browsers and client software.
• It has request/response-based.
• Client requests server through designated port to seek knowledge.
• HTTP can connect with the internet network through any port.
• The server responds through a message to transmit the request.
• Uniform resource locator (URLs) and HTML files, and other data are what is transferred.
• Tim Berners-Lee introduced HTTP in 1990 as a TCP/IP suite.
• The version now is the latest version.
• The first version of the latest version from HTTP 0.9.

World Wide Web (WWW)

• It combines web users with the resources via HTTP to give better communication.
• The WWW and the internet are different.
• The internet uses local network protocols.
• WWW is a combination with all information with web resources and user who relies on HTTP.
• Tim Berners-Lee introduced and created server at CERN in the UK. at 1989.
• WWW began in 1991 when public Internet started.
• The World Wide Web Consortium (W3C) governs network-based information.