Required technology

Visualization of a portion of the routes on the Internet.
Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems such as Sabre.[54]
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET.[55] The technologies that made the Arpanet possible spread and evolved.
In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. “Wireless” networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.
Computer architecture paradigms
There are many types of computer architectures:
Quantum computer vs Chemical computer
Scalar processor vs Vector processor
Non-Uniform Memory Access (NUMA) computers
Register machine vs Stack machine
Harvard architecture vs von Neumann architecture
Cellular architecture
The quantum computer architecture holds the most promise to revolutionize computing.[56]
Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms.
The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity.
Misconceptions

Main articles: Human computer and Harvard Computers


Women as computers in NACA High Speed Flight Station "Computer Room"
A computer does not need to be electronic, nor even have a processor, nor RAM, nor even a hard disk. While popular usage of the word “computer” is synonymous with a personal electronic computer, the modern[57] definition of a computer is literally “A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information.”[58] Any device which processes information qualifies as a computer, especially if the processing is purposeful.
Required technology
Main article: Unconventional computing
Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors. However, conceptually computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); an often quoted example.[citation needed] More realistically, modern computers are made out of transistors made of photolithographed semiconductors.
A central processing unit (CPU), also referred to as a central processor unit,[1] is the hardware within a computer that carries out the instructions of a computer program by performing the basic arithmetical, logical, and input/output operations of the system. The term has been in use in the computer industry at least since the early 1960s.[2] The form, design, and implementation of CPUs have changed over the course of their history, but their fundamental operation remains much the same.
A computer can have more than one CPU; this is called multiprocessing. Some integrated circuits (ICs) can contain multiple CPUs on a single chip; those ICs are called multi-core processors.
Two typical components of a CPU are the arithmetic logic unit (ALU), which performs arithmetic and logical operations, and the control unit (CU), which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.
Not all computational systems rely on a central processing unit. An array processor or vector processor has multiple parallel computing elements, with no one unit considered the "center". In the distributed computing model, problems are solved by a distributed interconnected set of processors.
The abbreviation CPU is sometimes used incorrectly by people who are not computer specialists to refer to the cased main part of a desktop computer containing the motherboard, processor, disk drives, etc., i.e., not the display monitor or keyboard.
Contents  [hide]
1 History
1.1 Transistor and integrated circuit CPUs
1.2 Microprocessors
2 Operation
3 Design and implementation
3.1 Control unit
3.2 Integer range
3.3 Clock rate
3.4 Parallelism
3.4.1 Instruction level parallelism
3.4.2 Thread-level parallelism
3.4.3 Data parallelism
4 Performance
5 See also
6 References and notes
6.1 Notes
6.2 References
7 External links
History[edit]