The Tech Storror

Wireless media: Wireless communication is a type of communication system that does not require any type of cable. In wireless communication, the sending device connects one computer to another computer or one device to another device through the radio web. Characteristics of Wireless Media: Wireless media do not use electrical or optical conductors or wires. In most cases, the Earth's atmosphere acts as the physical path for data transmission. Wireless systems are used when there are obstacles in the way of data transmission and installation of wired media is problematic. The three types of wireless media are -- (i) Radio Wave  (ii) Microwave   (ii) Infrared Radio wave: Network data is transmitted through radio transmission in the same way that signals are transmitted in radio. In this case every computer in the network can receive the signal sent by it. Radio wave frequencies are limited to 10 kHz to 1 GHz. The limited electromagnetic spectrum between 10 kilohertz and...

Control of power supply damage and its prevention Computers can have various problems related to power supply. Irregular supply of electricity is one of the problems related to computer power supply. Besides, not having proper voltage, frequent power supply, power return in shortest time interval, lack of earthing, fault in power supply unit, heating of internal parts of power supply unit, not getting proper voltage and signal at output power supply unit switch Not working mode etc. are some of the harmful regulators of power supply. All these problems and solutions are described below -- (a) Voltage problem : Damage to computers and other electrical appliances due to high voltage is a regular occurrence in our country. A voltage stabilizer can be used to avoid this condition. Many times when the voltage is much lower than required, any electrical appliance used in the home cannot be operated. In this case, the computer should be turned off. (b) Sudden power outage : Load shedding is a...

Things to do to prevent cyber crime It is always better to take determinative measures to prevent a crime than to take action against it after it has occurred. This also applies to online users. To avoid becoming a victim of cybercrime, one can easily stay free from cybercrime if some awareness and some preventive measures are always followed. Some of such preventive measures are described below: (i) One should refrain from presenting one's confidential information to others. (ii) Never send any photograph of yourself or someone you know online to a stranger or a chat friend. Because that kind of photography can be used for any evil purpose. (iii) Always use new and upgraded anti-virus to prevent virus attacks. (iv) Important data should always be backed up so that the data is not lost forever due to virus attack. (v) Never provide credit card number to any insecure website to stay financially risk free. (vi) Children should always monitor their browsing so that they do not access ...

Software maintenance tools Software maintenance tools and system tools used in Windows operating system for software maintenance are backup, character map, disk clean-up, disk defragmentation, file and setting transfer wizard, schedule task, security center, system information and system restore. Below are descriptions of three commonly used tools (Disk Clean-up, Scan Disk or Check Disk, and Disk Defragmentation): (a) Disk clean-up: Many unnecessary files accumulate in the computer system at various times, such as temporary files, files downloaded from the Internet, files stored in Recycle Bin. All these files occupy the memory or space of the computer system. All these unnecessary file systems can be deleted using disk clean-up tool. The following unnecessary files can be deleted using disk clean-up tool. * Temporary Internet files * Downloaded program files * Deposit file in recycle bin * Temporary files (b) Scan Disk: If there is any error in the saved file, it can be corrected us...

 Basic Concept on Data Security & Authentication Entity Level Security The security system is greatly strengthened by database authorization. Even then, security breaches do occur. Various unauthorized persons breach security through database misuse and accidents. But this is not desirable at all in case of database. Therefore, a security method called encryption is used in the database management system to further strengthen the security system. Data Recovery Database data is lost when the computer system fails or crashes due to any reason. The process by which this lost data can be recovered is called data recovery. Failures are of various types, namely-  (i) Transaction Failure (ii) Logical Error (iii) System Error  (iv) System Crash (v) Disk Failure Authorization Authorization is a process by which database security can be controlled. A database user can have different types of authorizations. This is dependent on database security. When the query processor transl...

Fundamental Operation of SQL SQL in data definition Data is defined or defined using SQL through the CREATE statement. An example is given below CREATE TABLE Employee() Emp_No NUMBER (5) NOT NULL Name CHAR (20) Skill CHAR (20) pay_rate NUMBER (10, 2); Explanation of the statement: (i) A table named Employee can be created through this SQL. The table will have four fields named Emp_No, Name, Skill and Pay_rate. (ii) Emp_No field will be NUMBER type data and this field will never be empty as it is declared as NOT NULL. (iii) Name field will be Character tight data and its length will be 20. (iv) The Skill field will be Character tight data and its length will be 20. (v) Pay_rate field will be NUMBER data type and its length will be 10 and 2 digits after decimal. Now let's say we want to add a new field to this table. Then type the following command: ALTER TABLE Employee ADD Phone_No NUMBER (10); Now type the following command to delete the Employee table. DROP TABLE Employee. SQL in ...

Clasification of computer network Computer communication, information sharing, electronic mail, electronic libraries, bulletin boards, etc. using computer networks are increasing in prevalence and spread. As a result, different types of networks are used in different countries of the world today. That is why the computer networks used in the world are classified from different points of view: namely-- (a) Classification of Networks by Ownership : (i) Private Networks and (ii) Public network. (b) Computer network according to type of work According to the type of work computer network can be mainly divided into three parts. These are- (i) Peer-to-peer network (ii) Client-server network (iii) Hybrid network (c) Classification of networks according to geographical extent : (i) Personal Area Network (PAN) (ii) Local Area Network (Local Area Network-LAN) (iii) Metropolitan Area Network (MAN) (iv) Wide Area Network (Wide Area Network-WAN) In general, network segmentation refers to the classi...

Hotspot, Wi-Fi, Wi-Max, Bluetooth Hotspot: Hotspot is a type of wireless network that provides internet connection to mobile computers and devices such as smartphones, PDAs, tablets, netbooks, notebooks or laptops. Currently, the three popular hotspot technologies are – 1. Wi-Fi 2. Wi-Max 3. Bluetooth Wi-Fi: Wi-Fi or wireless fidelity is a popular wireless technology that uses radio waves to connect any electronic device to a high-speed Internet connection or computer network to exchange data. It is technically known as IEEE 802.11b. Wi-Fi technology is relatively faster (11 Mbps) and less expensive than standard Ethernet and other common wired LAN technologies. Thus, the Wi-Fi wireless LAN connects laptop PCs, PDAs, smart phones, tabs and other devices with Wi-Fi modems to the rapidly growing business, public and the planet to easily connect to the Internet and other networks. A faster version (802.11g) with a speed of 54 Mbps promises widespread use of this technology. Features of Wi...

Difference Between Base Band and Broad Band Transmission Systems: Base Band: (1) In a baseband transmission system, the data sent from the computer is sent unaltered over the network connection. (2) Modulation is not required in baseband transmission systems. (3) In a baseband transmission system, multiple signals cannot be transmitted over a single pair of wires simultaneously. (4) Low cost in baseband transmission system. (5) Benefits are less available in baseband transmission systems. Broadband: (i) In broadband transmission system, the information received from the computer is modulated by high frequency and sent over the network connection. (ii) Amplitude modulation and demodulation are required in broadband transmission systems. (iii) In broadband transmission system it is possible to establish multiple connections simultaneously through one connection path (iv) Cost of broadband transmission system is high. (v) More benefits are available in broadband transmission systems. Repe...

Data transmission mode The mode of data movement depends on the direction of data movement. Data transmission modes are generally divided into three categories; namely- (i) Simplex mode or unidirectional mode, (ii) Half-duplex mode or meaning duplex mode, (iii) Full-duplex mode or pre-duplex mode or duplex mode. Simplex : The data transmission mode in which data is transmitted only in one direction is called simplex transmission mode. In this method data can be transmitted only in one direction. That is, the sending computer can send data to the receiving computer. But the receiving computer can never send the data to the sending computer. The first computer can only send data to the second computer. But the second computer cannot send data to the first computer. Half Duplex Mode : At this speed data can be sent in both directions but not simultaneously. When the sending computer sends data to the receiving computer, the receiving computer only receives the data. But the sender cannot ...