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"Computer technology" and "Computer system" redirect here. For the company, see Computer Technology Limited. For other uses, see Computer (disambiguation) and Computer system (disambiguation).
A computer is a general-purpose device that can be programmed to 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 of memory.
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.
Mechanical analog computers started appearing in first century and were later used in the medieval era for astronomical calculations. In World War II, mechanical analog computers were used for specialized military applications. During this time the first electronic digital computers were developed. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs). 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.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 consider 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.
Programming language
Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages,
programming languages are designed to permit no ambiguity and to be
concise. They are purely written languages and are often difficult to
read aloud. They are generally either translated into machine code by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques.
Program design
Program design of small programs is relatively simple and involves
the analysis of the problem, collection of inputs, using the programming
constructs within languages, devising or using established procedures
and algorithms, providing data for output devices and solutions to the
problem as applicable. As problems become larger and more complex,
features such as subprograms, modules, formal documentation, and new
paradigms such as object-oriented programming are encountered. Large
programs involving thousands of line of code and more require formal
software methodologies. The task of developing large software
systems presents a significant intellectual challenge. Producing
software with an acceptably high reliability within a predictable
schedule and budget has historically been difficult; the academic and
professional discipline of software engineering concentrates specifically on this challenge.
Bugs
Errors in computer programs are called “bugs.”
They may be benign and not affect the usefulness of the program, or
have only subtle effects. But in some cases, they may cause the program
or the entire system to “hang,” becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash. Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit,
code designed to take advantage of a bug and disrupt a computer's
proper execution. Bugs are usually not the fault of the computer. Since
computers merely execute the instructions they are given, bugs are
nearly always the result of programmer error or an oversight made in the
program's design.
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