Computer

A computer is a general purpose device that can be programmedto carry out a set of arithmetic or logical operations automatically. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem.

Conventionally, a computer consists of at least one processing element, typically a central processing unit (CPU), and some form ofmemory. The processing element carries out arithmetic and logic operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices allow information to be retrieved from an external source, and the result of operations saved and retrieved.

In World War II, mechanical analog computers were used for specialized military applications. During this time the first electronicdigital computers were developed. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).^[1]

Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.^[2] Simple computers are small enough to fit into mobile devices, and mobile computers can be powered by small batteries. Personal computers in their various forms are icons of the Information Age and are what most people think of as “computers.” However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.

Contents

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• 1 Etymology
• 2 History
  • 2.1 First general-purpose computing device
  • 2.2 Early analog computers
  • 2.3 The modern computer age begins
    • 2.3.1 The first electromechanical computers
    • 2.3.2 The introduction of electronic programmable computers with vacuum tubes
    • 2.3.3 Stored program computers eliminate the need for re-wiring
    • 2.3.4 Transistors replace vacuum tubes in computers
    • 2.3.5 Integrated circuits replace transistors
  • 2.4 Mobility and the growth of smartphone computers
• 3 Programs
  • 3.1 Stored program architecture
  • 3.2 Bugs
  • 3.3 Machine code
  • 3.4 Programming language
    • 3.4.1 Low-level languages
    • 3.4.2 Higher-level languages
  • 3.5 Program design
• 4 Components
  • 4.1 Control unit
  • 4.2 Arithmetic logic unit (ALU)
  • 4.3 Memory
  • 4.4 Input/output (I/O)
  • 4.5 Multitasking
  • 4.6 Multiprocessing
  • 4.7 Networking and the Internet
  • 4.8 Computer architecture paradigms
• 5 Misconceptions
  • 5.1 Required technology
• 6 Further topics
  • 6.1 Artificial intelligence
  • 6.2 Hardware
    • 6.2.1 History of computing hardware
    • 6.2.2 Other hardware topics
  • 6.3 Software
  • 6.4 Languages
  • 6.5 Professions and organizations
• 7 Degradation
• 8 See also
• 9 Notes
• 10 References
• 11 External links

Etymology

The first use of the word “computer” was recorded in 1613 in a book called “The yong mans gleanings” by English writer Richard Braithwait I haue read the truest computer of Times, and the best Arithmetician that euer breathed, and he reduceth thy dayes into a short number. It referred to a person who carried out calculations, or computations, and the word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.^[3]

History

Main article: History of computing hardware

Rudimentary calculating devices first appeared in antiquity and mechanical calculating aids were invented in the 17th century. The first recorded use of the word "computer" is also from the 17th century, applied to human computers, people who performed calculations, often as employment. The first computer devices were conceived of in the 19th century, and only emerged in their modern form in the 1940s.

Read More:http://en.wikipedia.org/wiki/Computer