Central processing unit

Central processing unit (CPU)

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.

facebook data Center

facebook data Center

 
The Facebook Prineville Data Center, which sits on a 120-acre parcel, is being built in two phases. The first half of the building, approximately 150,000 square feet, is complete. The second half, again approximately 150,000 square feet, will be completed at the end of 2011 and will have servers installed in line with demand.


Facebook has brought diversity to the job market at a time when unemployment has ranged from 17-20%,” said Prineville Mayor Betty Roppe. “During the past year Prineville has seen a loss of nearly 1,000 in population according to the US Census.  Facebook’s arrival has opened the market for other business recruitment. Their arrival has given the community a shot of OPTIMISM.”

Software

omputer software, or just software, is any set of machine-readable instructions (most often in the form of a computer program) that directs a computer's processor to perform specific operations. The term is used to contrast with computer hardware, the physical objects (processor and related devices) that carry out the instructions. Hardware and software require each other and neither has any value without the other.
Firmware is software that has been permanently stored in hardware (specifically in non-volatile memory). Thus, it has qualities of both software and hardware.
Software is a general term. It can refer to all computer instructions in general, or to any specific set of computer instructions. It is inclusive of both machine instructions (the binary code that the processor understands) and source code (more human-understandable instructions that must be rendered into machine code by compilers or interpreters before being executed).
On most computer platforms, software can be grouped into a few broad categories:

• System software is the basic software needed for a computer to operate (most notably the operating system);
• Application software is all the software that uses the computer system to perform useful work beyond the operation of the computer itself;
• Embedded software resides as firmware within embedded systems, devices dedicated to a single use. In that context there is no clear distinction between the system and the application software.

Software refers to one or more computer programs and data held in the storage of the computer. In other words, software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system. Program software performs the function of the program it implements, either by directly providing instructions to the digital electronics or by serving as an input to another piece of software. The term was coined to contrast to the term hardware (meaning physical devices). In contrast to hardware, software "cannot be touched".^[1] Software is also sometimes used in a more narrow sense, meaning application software only. Sometimes the term includes data that has not traditionally been associated with computers, such as film, tapes, and records.^[2]
Computer software is so called to distinguish it from computer hardware, which encompasses the physical interconnections and devices required to store and execute (or run) the software. At the lowest level, executable code consists of machine language instructions specific to an individual processor. A machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. Programs are an ordered sequence of instructions for changing the state of the computer in a particular sequence. It is usually written in high-level programming languages that are easier and more efficient for humans to use (closer to natural language) than machine language. High-level languages are compiled or interpreted into machine language object code. Software may also be written in an assembly language, essentially, a mnemonic representation of a machine language using a natural language alphabet. Assembly language must be assembled into object code via an assembler.

History

The first theory about software was proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem (decision problem).^[3] Colloquially, the term is often used to mean application software. In computer science and software engineering, software is all information processed by computer system, programs and data. The academic fields studying software are computer science and software engineering.
As more and more programs enter the realm of firmware, and the hardware itself becomes smaller, cheaper and faster as predicted by Moore's law, elements of computing first considered to be software, join the ranks of hardware. Most hardware companies today have more software programmers on the payroll than hardware designers^{[citation needed]}, since software tools have automated many tasks of Printed circuit board engineers. Just like the Auto industry, the Software industry has grown from a few visionaries operating out of their garage with prototypes. Steve Jobs and Bill Gates were the Henry Ford and Louis Chevrolet of their times^{[citation needed]}, who capitalized on ideas already commonly known before they started in the business. In the case of Software development, this moment is generally agreed to be the publication in the 1980s of the specifications for the IBM Personal Computer published by IBM employee Philip Don Estridge. Today his move would be seen as a type of crowd-sourcing. Computer hardware companies not only bundled their software, they also placed demands on the location of the hardware in a refrigerated space called a computer room.
Until that time, software was bundled with the hardware by Original equipment manufacturers (OEMs) such as Data General, Digital Equipment and IBM^{[citation needed]}. When a customer bought a minicomputer, at that time the smallest computer on the market, the computer did not come with Pre-installed software, but needed to be installed by engineers employed by the OEM. Computer hardware companies not only bundled their software, they also placed demands on the location of the hardware in a refrigerated space called a computer room. Most companies had their software on the books for 0 dollars, unable to claim it as an asset (this is similar to financing of popular music in those days).
When Data General introduced the Data General Nova, a company called Digidyne wanted to use its RDOS operating system on its own hardware clone. Data General refused to license their software (which was hard to do, since it was on the books as a free asset), and claimed their "bundling rights". The US Supreme Court set a precedent called Digidyne v. Data General in 1985, and the Supreme Court let a 9th circuit decision stand, and Data General was eventually forced into licensing the Operating System software because it was ruled that restricting the license to only DG hardware was an illegal tying arrangement.^[4] Unable to sustain the loss from lawyer's fees, Data General ended up being taken over by EMC Corporation. The Supreme Court decision made it possible to value software, and also purchase Software patents.

Computer

Computer

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. 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 that can change the order of operations based on stored information. Peripheral devices allow information to be retrieved from an external source, and the result of operations saved and retrieved.
The first electronic digital computers were developed between 1940 and 1945. Originally they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).^[1] In this era mechanical analog computers were used for military applications.
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

History of computing

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.

Home network

 

 

 

A home network or home area network (HAN) is a residential local area network (LAN) for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service provisioned by fiber-to-the-home or via Cable Internet access, Digital Subscriber Line (DSL) or mobile broadband by Internet service providers (ISPs). If an ISP only provides one IP address, a router including network address translation (NAT), proxy server software and typically a network firewall, allows several computers to share the external IP address. The router function may be assumed by a PC with several network interfaces, but a dedicated router device is more common, often including a wireless accesspoint, providing WiFi access.

  

Home group

A home group is a feature that allows shared disk access, shared printer access and shared scanner access among all computers and users (typically all family members) in a home, in a similar fashion as in a small office workgroup, e.g., by means of distributed peer-to-peer networking (without a central server). Additionally, a home server may be added for increased functionality.
A Windows HomeGroup is a new feature in Microsoft Windows 7 that simplifies file sharing. All users (typically all family members), except guest accounts, may access any shared library on any computer that is connected to the home group. Passwords are not required from the family members during logon. Instead, secure file sharing is possible by means of a temporary password that is used when adding a computer to the HomeGroup.

 

Physical transmission media

Home networks may use wired or wireless technologies. Wired systems typically use shielded or unshielded twisted pair cabling, such as any of the Category 3 (CAT3) through Category 6 (CAT6) classes, but may also be implemented with coaxial cable, or over the existing electrical power wiring within homes

 

Computer network

 

 

 

 

"Computer networks" redirects here. For the periodical, see Computer Networks (journal).

"Datacom" redirects here. For other uses, see Datacom (disambiguation).

A computer network is a telecommunications network that allows computers to exchange data. The physical connection between networked computing devices is established using either cable media or wireless media. The best-known computer network is the Internet.
Network devices that originate, route and terminate the data are called network nodes.^[1] Nodes can include hosts such as servers and personal computers, as well as networking hardware. Two devices are said to be networked when a process in one device is able to exchange information with a process in another device.
Computer networks support applications such as access to the World Wide Web, shared use of application and storage servers, printers, and fax machines, and use of email and instant messaging applications. The remainder of this article discusses local area network technologies and classifies them according to the following characteristics: the physical media used to transmit signals, the communications protocols used to organize network traffic, along with the network's size, its topology and its organizational intent.

 Properties

Computer networking may be considered a branch of electrical engineering, telecommunications, computer science, information technology or computer engineering, since it relies upon the theoretical and practical application of the related disciplines.
A computer network has the following properties:

Facilitates interpersonal communications

People can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.

Allows sharing of files, data, and other types of information

Authorized users may access information stored on other computers on the network. Providing access to information on shared storage devices is an important feature of many networks.

Allows sharing of network and computing resources

Users may access and use resources provided by devices on the network, such as printing a document on a shared network printer. Distributed computing uses computing resources across a network to accomplish tasks.

May be insecure

A computer network may be used by computer Hackers to deploy computer viruses or computer worms on devices connected to the network, or to prevent these devices from accessing the network (denial of service).

May interfere with other technologies

Power line communication strongly disturbs certain forms of radio communication, e.g., amateur radio. It may also interfere with last mile access technologies such as ADSL and VDSL.

May be difficult to set up

A complex computer network may be difficult to set up. It may be costly to set up an effective computer network in a large organization.

 

Blogger My Friend

This is the blog of a friend and me.
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1.Jinyanavat :

2.Jiraphat :

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10.Phanathon :

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18.Kamonchanok :

19.Kanvara :

20.Kornkanya :

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