Computers

A computer is a machine (mostly electronic) that is able to take information (input), and process it to make new information (output). Calculating machines have existed for much of human history. A computer is a programmable machine. The two principal characteristics of a computer are: It responds to a specific set of instructions in a well-defined manner and it can execute a prerecorded list of instructions (a program). Early examples are the astrolabe and the abacus. There are four main processing steps in a computer, and they are: inputting, storage, outputting and processing.

Modern computers are very different from early computers. They can do billions of calculations per second. Most people have used a personal computer in their home or at work. Computers do many different jobs where automation is useful. Some examples are controlling traffic lights, vehicle computers, security systems, washing machines and digital televisions.

A computer user can control it by a user interface. Input devices include keyboard, mouse, buttons, and touch screens. Some very sophisticated computers can also be controlled with voice commands or hand gestures or even brain signals through electrodes implanted in the brain or along nerves.

Computers can be designed to do almost anything with information. Computers are used to control large and small machines which in the past were controlled by humans. They are also in homes, where they are used for things such as listening to music, reading the news and writing.

Modern computers are electronic computer hardware. They do mathematical arithmetic very quickly but computers do not really "think". They only follow the instructions in their software programs. The software uses the hardware when the user gives it instructions, and gives useful output.

Computer programs are designed or written by computer programmers. A few programmers write programs in the computer's own language called machine code. Most programs are written using a programming language like C++, Java, and Fortran. These programming languages are more like the language with which one talks and writes every day. The compiler translates the user's instructions into binary code (machine code) that the computer will understand and do what is needed.

 Source : Wikipedia

Computer Software

Computer software, or just software, is a collection of computer programs and related data that provide the instructions for telling a computer what to do and how to do it. In other words, software is a conceptual entity which is a set of computer programs, procedures, and associated documentation concerned with the operation of a data processing system. We can also say software refers to one or more computer programs and data held in the storage of the computer for some purposes. In other words software is a set of programs, procedures, algorithms and its documentation. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software.


System Software

System software provides the basic functions for computer usage and helps run the computer hardware and system. It includes a combination of the following:

• Device drivers
• Operating systems
• Servers
• Utilities
• Window systems

System software is responsible for managing a variety of independent hardware components, so that they can work together harmoniously. Its purpose is to unburden the application software programmer from the often complex details of the particular computer being used, including such accessories as communications devices, printers, device readers, displays and keyboards, and also to partition the computer's resources such as memory and processor time in a safe and stable manner.


Programming software
Programming software usually provides tools to assist a programmer in writing computer programs, and software using different programming languages in a more convenient way. The tools include:

• Compilers
• Debuggers
• Interpreters
• Linkers
• Text editors

An Integrated development environment (IDE) is a single application that attempts to manage all these functions.


Application software 

Application software is developed to perform in any task that benefits from computation. It is a broad category, and encompasses software of many kinds, including the internet browser being used to display this page. This category includes:

• Business software
• Computer-aided design
• Databases
• Decision making software
• Educational software
• Image editing
• Industrial automation
• Mathematical software
• Medical software
• Molecular modeling software
• Quantum chemistry and solid state physics software
• Simulation software
• Spreadsheets
• Telecommunications (i.e., the Internet and everything that flows on it)
• Video editing software
• Video games
• Word processing

Hardware: Output Devices

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.
In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside.

Some of the Output Devices

Display Devices
A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information is supplied as an electrical signal, the display is called an electronic display.The Most common form of display devices are the Computer Monitors.


Printers
In computing, a printer is a peripheral which produces a text or graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a USB cable to a computer which serves as a document source.
Impact Printer
Impact printers rely on a forcible impact to transfer ink to the media, similar to the action of a typewriter. The impact printer uses a print head that hits the surface of the ink ribbon, which presses the ink onto the paper. All but the dot matrix printer rely on the use of formed characters, letterforms that represent each of the characters that the printer was capable of printing.
Non Impact Printers
Pen-based plotters were an alternate printing technology once common in engineering and architectural firms. Pen-based plotters rely on contact with the paper (but not impact, per se) and special purpose pens that are mechanically run over the paper to create text and images.
Thermal Printers
Thermal printers work by selectively heating regions of special heat-sensitive paper. Monochrome thermal printers are used in cash registers, ATMs, gasoline dispensers and some older inexpensive fax machines. Colours can be achieved with special papers and different temperatures and heating rates for different colours; these coloured sheets are not required in black-and-white output. One example is the ZINK technology.
Mobile Printers
Mobile Printers are hand held small and portable printers.


Audio Output Devices
Any devices that allow the computer to play audio is an audio audio output device. The most common form of audio output devices are computer speakers.


Other Forms of Output Devices

• Data projector
• Force feedback,etc....