Computer Engineering

 . Internet Technologies is a technical field that covers the necessary skills to develop applications on the internet or internet based systems, harnessing e-commerce, cloud, mobile, and web based technologies. The Internet is a vast network that connects computers all over the work. Through the internet people can share information and communicate from anywhere with an internet connection. Internet is a global network of billions of computers and other electronic devices with the internet, its possible to access almost any information, communicate with anyone else in the work and do much more. The internet is a global wide area network that connects computer systems across the work. It includes several high bandwidth data lines that comprise the internet "backbone". These lines are connected to major internet hubs that distribute data to other locations, such as web server and ISPs. Advantage of Internet Source of Information Source of Entertainment Keep Informed Online Sho

 . Open system interconnection (OSI) Model explains how packet travels through various layers to other devices on a network, even if the sender and destination have different types of network media. Layer 1(Physical layer):  Function  To activate, maintain, deactivate the physical connection.  To define voltage and data rates needed for transmission.  To convert the digital bits into electrical signals.  To decide weather the transmission the transmission is simplex, half or full duplex.  Physical layer doesn’t perform the detection and correction of errors. Layer 2 (Datalink layer):  Framing (stream of bits into manageable data units):  The datalink layer divides the stream of bits received from the network layer into frame manageable data units called frames.  Physical addressing (MAC Address):  Data link layer adds a header to header to the frame to define the sender and receiver of the frame. Flow Control (mechanism for overwhelming the receiver):  If the data rate at which the dat

 . E-Business Strategy: An e-business strategy defines a long-term plan for putting in place the right digital technology for a company to manage its electronic communications with all partners. E-Commerce Strategy: E-commerce strategy are interconnected plans that drive your business operations. There are three major ecommerce strategies to consider: product strategy, customer relationship and corporate considerations. Each of these must work together to ensure the best possible outcomes for your brand.  Internet Revenue: means Revenue earned as a result of Services by HI in which (i) a majority of the research or other information gathering activities in connection with such Services were conducted by means of the Internet or (ii) fifty percent (50%) or more of surveys completed in connection with such Services were collected over the Internet. Barriers Of E-Commerce:   The Issue of cybersecurity Customer experience  Maintaining customer loyalty Product return & refunds  Onlin

 . The some basic component of computer network are given below: Server : Server are computers that hold shared programs, files and the network operating system. Servers allow access to network resources to all the users of the network. Modem :  A modem is a hardware device that allows the computer to connect to the internet over the existing telephone line. It is not integrated with the motherboard rather than it is installed on the PCI slot found on the motherboard. It stands for Modulator/Demodulator. It converts the digital data into an analog signal over the telephone lines. Routers : Routers help you to connect with multiple networks. It enables you to share a single internet connection with multiple devices and saves money. This networking component acts as a dispatcher, which allows you to analyze data sent across a network. It automatically selects the best route for data to travel and send it on its way. Repeater :  A repeater is a powerful network component that is used to r

 . Computer Network Architecture is defined as the physical and logical design of the software, hardware, protocols and media of the transmission of data. Simply we can say that how computers are organized and how tasks are allocated to the computer. There are two types of Computer Network Architecture 1. Peer-To-Peer  Network Peer-To-Peer network is a network in which all the computers are linked together with equal privilege and responsibilities for processing the data. Peer-To-Peer network is useful for small environments, usually up to 10 computers. Peer-To-Peer network has no dedicated server. Special permissions are assigned to each computer with the resource is down. Advantages of Peer-To-Peer Network It is less costly as it does not contain any dedicated server. If one computer stops working but, other computers will not stop working. It is easy to set up and maintain as each computer manages itself. Disadvantage of Peer-To-Peer Network In the case of Peer-To-Peer network, it d

 . Transmission Medium A communication channel is called a medium. There are two types of media:  Guided (Wired) Media :   Guided Media is a communication medium which allows the data to get guided along it i.e. physical connection is need.  Examples : Twisted P Twisted Pair Cable  A twisted pair consists of two conductors (copper), each with its own plastic insulation, twisted together.  One of the wires is used to carry signals to receiver, and the other is used only as a ground reference.  A signal is usually carried as the difference in voltage between the two wires in the pair. This provides better immunity to external noise because the noise tends to affect both wire the same, leaving the differential voltage unchanged.  Frequency range for twisted pair cable is 100Hz to 5MHz.  Coaxial Cable  Coaxial cable carries signals of higher frequency range than those in twisted pair cable.  It has a central core conductor of solid or standard wire (usually copper) enclosed in an insulatin

 . Local Area Network (LAN)  A LAN is a network that is used for communicating among computer devices, usually within an office building or home.   LAN’s enable the sharing of resources such as files or hardware devices that may be needed by multiple users • • Is limited in size, typically spanning a few hundred meters, and no more than a mile.  Is fast, with speeds from 10 Mbps to 10 Gbps.  Requires little wiring, typically a single cable connecting to each device.  Has lower cost compared to MAN’s or WAN’s.  LAN’s can be either wired or wireless. Twisted pair, coax or fiber optic cable can be used in wired LAN’s. Advantages of LAN :    The data is transferred at an extremely faster rate in local Area Network.  Local area network (LAN) provides higher security. Disadvantages of LAN :   Initial cost of installing local area network is quite high.  Unauthorized user can access critical data of an organization in case LAN admin is not able to secure centralized data repository.  Wide Are

 . Introduction of Communication System  The fundamental purpose of a communications system is the exchange of data between two parties. Below figure presents one particular example, which is communication between a workstation and a server over a public telephone network. Another example is the exchange of voice signals between two telephones over the same network.  Some basic element of communication system are given bellow Source : This device generates the data to be transmitted; examples are telephones and personal computers. Transmitter : Usually, the data generated by a source system are not transmitted directly in the form in which they were generated. Rather, a transmitter transforms and encodes the information in such a way as to produce electromagnetic signals that can be transmitted across some sort of transmission system. For example, a modem takes a digital bit stream from an attached device such as a personal computer and transforms that bit stream into an analog signa

 . The Utility Software is system software that helps to maintain the proper and smooth functioning of a Computer System. It assists the Operating System to manage, organize, maintain and optimize the functioning of the computer system. Utility software performs certain tasks like virus detection, installation and uninstallation and backup, detection of unwanted files, etc. Some examples are antivirus software, file management tools, compression tools, disk management tools etc. Antivirus Software Viruses are malicious files that can infect a computer's hardware and software. Antivirus software monitors the files that are coming into the computer's drives to detect the presence of concerning threats. This type of utility software also scans all the files regularly and discards any malicious files that may lurk or cause problems with the computer. Firewalls A Firewall is a network security device that monitors and filters incoming and outgoing network traffic based on a organiza

 . Operating System (OS) is a computer program (System Software) that acts as an intermediate between the user and computer hardware. This is the first software we see when we turn on the computer and again the last software we see when the computer is turned off. It is very difficult for the users of computer to understand how to operate them directly. So, OS becomes the interpreter between the computer hardware and user. It interprets the command of users to the hardware and presents the output to user in a suitable format produced by hardware. Types of Operating System There are 7 types of operating system which are given bellow: Batch System :  A batch  system is one which jobs are bundled together with the instruction necessary to allow them to be processed without user intervention. The simple Operating System also called monitor is system software responsible for interpreting and carrying out the instructions in the batch jobs. When the monitor started a job, it handed over cont

 . Disk Disk storage is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism.  Pen drives A pen drive is a portable Universal Serial Bus (USB) flash memory device for storing and transferring audio, video and data file from a computer. As long as the desktop or laptop has a USB port, and the pen drive is compatible with operating system, it should be easy to move the data from the hard drive to the device and to another computer in a matter of minutes. Optical media Optical media is a flat and circular disk which is coated with reflective plastic material that can be altered by laser light. It consist a single spiral track that starts from the edge to the center of disk.  Due to its spiral shape, it can access large amount of data sequentially, for example music and video.  Optical disks can store larg

 . The component of computer system are given bellow: Processors The processor or the CPU is the main component of the computer. Select a processor based on factors like its speed, performance, reliability and motherboard support. Pentium Pro, Pentium 2 and Pentium 4 are some of the processor. Motherboard Motherboard is the hub, which is used to connect all the essential component of a computer. It is a large Printed Circuit Board (PCB), having many chip, connectors and other electronics mounted on it. The motherboard contains the processor, memory chips, interfaces and sockets, etc. BIOS The BIOS contain the instructions for the starting up of the computer.  It performs a Power On Self  Test (POST) that check that the hardware is functioning properly and the hardware device are present. It check whether the operating system is present on the hardware drive. Power Supply A Power Supply Unit (PSU) is a hardware device that converts AC electricity into DC electricity and then distributes

 . Computer is a device, which is capable of doing almost all the works, which can be programmed by the user. But there are some functions, which are impossible for a computer to perform. Following are some of the capabilities and limitations of computer: Capabilities Computer can do jobs with 100% accuracy and in a very fast speed in comparison to any other devices or human. It is possible to show and do the things, which are impossible for humans. Computer provides faster and cheaper communication with the user of various communication technologies.  It can perform almost all the works but for any purpose, user must provide proper program and necessary hardware. Limitations Computer is dull machine. It doesn't have intelligence on it. So, whatever i9t does, that is with the help of programs and devices developed by human. If such assistances are not provided, it will not be able to perform the simple of the simplest works, too. If any error occurs in its structure or circuitry, t

 . Centralized Database A centralized database in which a single central Database accessed by multiple users. It's easier to organized data, edit query and also can backup easily. They are located on particular location. The controlling mechanism is also centralized and data are deposited in a central location. Files are kept on the base of the location of disk drives and names. It is only suitable for small organization and small scale operations. Advantage of centralized database that it is easy to maintain. Disadvantage is if the server is destroyed by some catastrophic damage like flood, fire whole data is lost. Distributed Database Distributed database is dispersed across many geographical locations. There are multiple database storing different types of file and they connected to each other. Its security is very much crucial part because it can be tapped or hacked in between the transmission. Advantage of distributed is the problem in one location will not affect entire  syst

. Third Normal Form (3NF) A table (relation is said to be in 3NF if and only if. 1. It is in 2NF 2. No non-prime attribute is transitively dependent on primary key.                                                    OR Transitively functional dependency of non-prime attribute on any supper key should be removed. In other words 3NF can be explain as a table is in 3NF if it is in 2NF  and for each functional dependency X - Y at list one of the following condition holds. X is a supper key of table. Y is a prime attribute of table. An attribute that is a path of the candidate key is known as prime attributes. Student Detail Supper key : {S_id}, {S_id,S_Name},{S_id,S_Name,Age} Candidate key : {S_id} Non-Prime attribute : All attributes except S_id. Functional dependency of above table are: S_id : S_name S_id : Age S_id : Gender S_id : Hostel-Name Gender : Hostel-Name     Thus in above relation contains transitive dependency i.e. S_id ->Gender, Geder->Hostel_Name & S_id->Hostel_

 . Second Normal Form (2NF) A table (Relation) is said to be in 2NF if and only if: It is in 1NF. Every non-prime attribute is fully dependent on the primary keys of the relation. OR No non-prime attribute is partially dependent the proper subset if any candidate key of the table. An attribute that is not part of any candidate key is known as non prime attribute. Example Suppose a school wants to store the data of teachers and the subject they tech. They create a table that looks like following. Candidate key: {Employee_id, Subjects}                                   Non-prime attribute: teacher_age The table is in 1NF because each attribute has atomic value. However, it is not in 2NF because non-prime attribute teacher age is partially dependent on proper subject of candidate key, ie Non-prime attribute this violet the rule for 2NF as the rule says, "No non-prime attribute is partially dependent the proper subject of any candidate key of the table". We can convert the above

 . Database Model This way in which information is sub devised and managed within a database is refereed as data model. Each DBMS is based on data models. The data models can be classification into three major group Hierarchical Database Model Network Database Model Relational Database Model 1. Hierarchical Database Model It organized data is a tree structure, their is hierarchy of parent and child sequence. This structure implied that a record can help replicated information generally child  data segment. It increases data redundancy as a result of which it is not used often but it is easy to implement due to its limited rules. Hierarchical database technology is used for high-volume transaction processing and MIS (Management Information System) applications. Few new database are developed with hierarchical DBMSs since newer applications tend to have broader needs than simply translation processing of summarization of transaction data.  Advantage  It is the easiest model of database A