Computer hacking is the practice of modifying computer hardware and software to accomplish a goal outside of the creator’s original purpose. People who engage in computer hacking activities are often called hackers. Since the word “hack” has long been used to describe someone who is incompetent at his/her profession, some hackers claim this term is offensive and fails to give appropriate recognition to their skills.
Computer hacking is most common among teenagers and young adults, although there are many older hackers as well. Many hackers are true technology buffs who enjoy learning more about how computers work and consider computer hacking an “art” form. They often enjoy programming and have expert-level skills in one particular program. For these individuals, computer hacking is a real life application of their problem-solving skills. It’s a chance to demonstrate their abilities, not an opportunity to harm other
First Generation (1940-1956)
Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
Second Generation (1956-1963)
Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers
The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Second-generation computers moved from cryptic binary machine language to symbolic.
Third Generation (1964-1971)
Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
Fourth Generation (1971-Present)
Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld device.
Fifth Generation (Present and Beyond)
Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come.
Computer disadvantages are as follows; Violation of Privacy, it is crucial that personal and confidential records stored in computers be protected properly. Impact on Labor Force, although computers have improved productivity and created an entire industry with hundreds of thousands of new jobs, the skills of hundreds of thousands employees are replaced by computers. Health Risks, prolonged or improper computer use can lead to head injuries or disorders. Computer users can protect themselves from health risks through proper workplace design, good posture while at the computer, and appropriately spaced work breaks. Impact on the Environment, Computer manufacturing processes and computer waste are depleting natural resources and polluting the environment.
Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation.
Computer viruses are often spread by attachments in e-mail messages or instant messaging messages. That is why it is essential that you never open e-mail attachments unless you know who it's from and you are expecting it.
Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.Computer viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.To help avoid computer viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, run your computer as a standard user(not as administrator) and that you follow a few basic rules when you surf the Internet, download files, and open attachments.
Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection.
The time taken to perform any task by computer is called speed of computer. As we know computer can work very fast. It takes only few seconds for calculations that we take hours to complete.
You will be surprised to know that computer can perform millions(1,000,000) of instructions and even more per second. The speed of computer is measured in terms of Mega Hertz(MHZ),Giga Hertz(GHZ),etc. Now a days we have GHZ speed computer Hertz is the unit of frequency that is no of signals per second.
The Fractions of seconds are given below.
Unit of time Part of second Unit of speed
Milliseconds(ms) one thousands 1/1,000 kilo hertz(KHZ)=10*3 HZ
Micro seconds one millionth 1/1,000,000 Mega Hertz(MHZ)=10*6 HZ
(ms) one billionth 1/1,000,000,000 Giga Hertz(GHZ)=10*9 HZ
Nanoseconds(ns) one trillionth 1/1,000,000,000,000 Tera Hertz(THZ)=10*12HZ
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