Mouse

In computing, a mouse (plural mouses, mice, or mouse devices) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input. The mouse's motion typically translates into the motion of a pointer on a display, which allows for fine control of a Graphical User Interface.

The name mouse, originated at the Stanford Research Institute, derives from the resemblance of early models (which had a cord attached to the rear part of the device, suggesting the idea of a tail) to the common mouse.

The first marketed integrated mouse – shipped as a part of a computer and intended for personal computer navigation – came with the Xerox 8010 Star Information System in 1981.

However, not until appearance of Apple Macintosh community masses really had idea of this device's existence: back in 1984, a prominent PC coloumnist commented the release of this new computer with a mouse: “There is no evidence that people want to use these things.”

Mouses now come with most computers although they can be bought separately.

http://en.wikipedia.org/wiki/Computer_mouse

Keyboard

After punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers. During the 1980s and 1990s almost all computers came equipped with them as the main form of interaction, and most users are familiar with using them.

There are different types of keyboard technologies.

The most popular layout of keys on the modern-day English keyboard is called the QWERTY design, based on the most popular typewriter keyboard layout further extended to the standard 104-key PC keyboard layout, with the addition of cursor keys, a calculator-style numeric keypad, two groups of special function keys, a key for the Windows Start menu (on IBM and clones), and other modifier keys. Some computer manufacturers have added keys specifically related to the Internet and e-mail, but these have not become standard.

The fastest typists (as of 2007) use a stenograph, a kind of chorded keyboard used by most court reporters and closed caption reporters.

Despite the development of alternative input devices such as the mouse, touch sensitive screens, pen devices, character recognition, voice recognition, and improvements in computer speed and memory size, the keyboard remains the most commonly used and most versatile device used for direct human input into computers.

http://en.wikipedia.org/wiki/Alphanumeric_keyboard

CPU

A central processing unit (CPU) is a machine that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage. The term itself and its initialism have been in use in the computer industry at least since the early 1960s (Weik 1961). The form, design and implementation of CPUs have changed dramatically since the earliest examples, but their fundamental operation has remained much the same.

Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, computer. However, this costly method of designing custom CPUs for a particular application has largely given way to the development of mass-produced processors that are suited for one or many purposes. This standardization trend generally began in the era of discrete transistor mainframes and minicomputers and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in everything from automobiles to cell phones to children's toys.

http://en.wikipedia.org/wiki/Central_processing_unit

The History

A computer is a machine that manipulates data according to a list of instructions.

The first devices that resemble modern computers date to the mid-20th century (1940–1945), although the computer concept and various machines similar to computers existed earlier. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers (PC). Modern computers are based on tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space. Today, simple computers may be made small enough to fit into a wristwatch and be powered from a watch battery. Personal computers, in various forms, are icons of the Information Age and are what most people think of as "a computer"; however, the most common form of computer in use today is the embedded computer. Embedded computers are small, simple devices that are used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and children's toys.

The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.