Computer science

Operating Systems for Mobile Devices

2013-05-13T05:33:00.002-07:00

The operating systems that we've been talking about were designed to run on desktop or laptop computers. Mobile devices such as phones, tablet computers, and mp3 players are very different from desktop and laptop computers, so they run operating systems that are designed specifically for mobile devices. Examples of mobile operating systems include Apple iOS, Windows Phone, and Google Android.

Operating Systems for mobile devices generally aren't as fully-featured as those made for desktop or laptop computers, and they aren't able to run all of the same software. However, you can still do a lot of things with them, such as watching movies, browsing the internet, managing your calendar, playing games, and more.

Apple OS running on an iPad

Linux

2013-05-13T05:27:00.003-07:00

Linux (pronounce LINN-ux) is a family of open source operating systems, which means that they can be modified and distributed by anyone around the world. This is very different from proprietary software like Windows, which can only be modified by the company that owns it (Microsoft). The advantages of Linux are that it is free, and there are many different distributions (or versions) that you can choose from. Each distribution has a different look and feel, and the most popular ones include Ubuntu, Mint, and Fedora.

Linux is named after Linus Torvalds, who created the Linux kernel in 1991. The kernel is the computer code that is the central part of an operating system.

According to StatCounter Global Stats, Linux users account for less than 1% of the operating systems market as of January 2013. However, most servers run Linux because it's relatively easy to customize.

To learn more about different distributions of Linux, visit the Ubuntu, Mint, and Fedora websites.

Apple Mac OS

2013-05-13T05:20:00.001-07:00

Mac OS is a line of operating systems created by Apple Inc. It comes preloaded on all new Macintosh computers, or Macs. All of the recent versions are known as Mac OS X (pronounced Mac O-S Ten), and their specific version names are Mountain Lion (released in 2012), Lion (2011), and Snow Leopard (2009). Apple also offers a version called Mac OS X Server, which is designed to be run on servers.
According to StatCounter Global Stats, Mac OS X users account for 7.5% of the operating systems market as of January 2013 - much lower than the percentage of Windows users (over 90%). One reason for this is that Apple computers tend to be more expensive. However, many people prefer the look and feel of Mac OS X.

To learn more about Macintosh computers and OS X, check out our Mac OS X Mountain Lion tutorial.

Microsoft Windows

2013-05-13T05:16:00.002-07:00

Microsoft created the Windows operating system in the mid-1980s. Over the years, there have been many different versions of Windows, but the most recent ones are Windows 8 (released in 2012), Windows 7 (2009), and Windows Vista (2007). Windows comes preloaded on most new PCs, which helps to make it the most popular operating system in the world.
If you're buying a new computer or upgrading to a newer version of Windows, you can choose from several different editions of Windows, such as Home Premium, Professional, and Ultimate. You may need to do some research to decide which edition is right for you.

Visit Microsoft's Windows page to learn more about this operating system
Check out our tutorials on Windows 8, Windows 7, and Windows XP for more information.

Introduction to Operating Systems

2013-05-13T05:06:00.002-07:00

An operating system or OS is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer and software programs would be useless. In the picture to the right, is an example of Microsoft Windows XP, a popular operating system and what the box may look like if you were to visit a local retail store to purchase it.

Examples of computer operating systems

Microsoft Windows 7 - PC and IBM compatible operating system. Microsoft Windows is the most commonly found and used operating system.
Apple MacOS - Apple computer operating system. The only Apple computer operating system.
Ubuntu Linux - A popular variant of Linux used with PC and IBM compatible computers.
Google Android - operating system used with Android compatible phones.
iOS - Operating system used with the Apple iPhone.

The Operating System's Job

You've probably heard the phrase boot your computer, but do you know what that means? Booting is the process that occurs when you press the power button to turn your computer on. During this process (which may take a minute or two), the computer does several things:

It runs tests to make sure everything is working correctly.
It checks for new hardware.
It then starts up the operating system.

Windows 7 start up screen

Once the operating system has started up, it manages all of the software and hardware on the computer. Most of the time, there are many different programs running at the same time, and they all need to access your computer's Central Processing Unit (CPU), memory, and storage. The operating system coordinates all of this to make sure that each program gets what it needs. Without the operating system, the software wouldn't even be able to talk to the hardware, and the computer would be useless.

Modern operating systems use a Graphical User Interface, or GUI (pronounced "gooey"). A GUI lets you use your mouse to click on icons, buttons, and menus, and everything is clearly displayed on the screen using a combination of graphics and text.
Each operating system's GUI has a different look and feel, so if you switch to a different operating system it may seem unfamiliar at first. However, modern operating systems are designed to be easy to use, and most of the basic principles are the same.

Before GUIs, computers had a command-line interface, which meant the user had to type every single command to the computer, and the computer would only display text.

Computer hardware

2013-03-30T12:48:00.003-07:00

Computers Hardware are a group of physical elements that make up a computer system. This then known refers to the parts of physical or computer components such as monitor, keyboard and computer and data storage, hard disk drive, mouse, printers, central processing unit (graphic cards, sound cards, memory, motherboard and chips), etc., all the physical objects that can be felt Indeed. In contrast, the program exists as ideas, and application, and concepts, and symbols, but has no substance. A combination of hardware and software make up the computing system unusable

Basic computer components

Input devices

Keyboard
Image scanner
Microphone
Pointing device
Graphics tablet
Joystick
Light pen
Mouse
Pointing stick
Touchpad
Touchscreen
Trackball
Webcam
Softcam

Output devices

Monitor
Printer
Speakers
Plotter

Removable data storage

Optical disc drive
CD-RW
DVD+RW
Disk pack
Floppy disk
Memory card
USB flash drive

Computer case

Central processing unit (CPU)
Hard disk / Solid-state drive
Motherboard
Network interface controller
Power supply
Random-access memory (RAM)
Sound card
Video card

Data ports

Ethernet
FireWire (IEEE 1394)
Parallel port
Serial port
Universal Serial Bus (USB)

Telecommunications equipment

2013-03-30T12:32:00.004-07:00

Communication devices are used for communication purposes.

Since 1990 become blurred boundaries between communications equipment and information technology equipment as a result of the growth of the Internet and its role in increasing the data transfer communicationAnd communication devices can be divided broadly down into the following categories:

Switching equipment
Analog switches
Numeric keys

Transmission equipment

Transfer lines
Fiber Optic

Transceiver stations
MMS
Local loops
Communications satellites

    Customer premises equipment
        Special keys
        Local Area Networks
        Modems
        Mobile phones
        Landlines
        Answer machines
        Remote printing machines
        Fax Machines
        Call
        Routers
Sellers
Five world equipment and telecommunications larger (eg: mobile-phone) companies measured by revenue applicable 2011 are:

Sweden Ericsson
China's Huawei
France Alcatel-Lucent
Finland / Germany, Nokia Siemens Networks
China ZTE

The world's five largest companies routing and switching revenue measured in force in the first quarter of 2012 are:

USA Cisco Systems
France Alcatel-Lucent
China's Huawei
United States Juniper Networks
China ZTE

The world's 10 largest mobile phone companies in terms of sales and unit of measurement in the fourth quarter of 2012 is (global market share indicated in brackets):

South Korea's Samsung (22.7%)
Nokia of Finland (18.0%)
United States Apple (9.2%)
China ZTE (3.4%)

Information technology

2013-03-30T12:12:00.001-07:00

Information Technology (IT) is the application of computers and telecommunications equipment and wireless storage and retrieval, transfer and data processing, and be a valuable business scope or other term usually used enterprise.The synonym for computers and computer networks, but also includes other technologies used in the distribution of information such as television and telephones. And many industries linked with information technology, such as computers and software, electronics, Internet, and telecommunications equipment, and electronic commerce and other
The scope of business, Information Technology Association of America has identified information technology as "the study and design, development and application support and implement or manage information systems based on computer. And responsibilities for workers in the field of network management and include, software development and installation, planning and management enterprise IT life cycle, that is which maintain the hardware and software. upgrade, and replace

The human storage and retrieval, processing and transfer of information since the Sumerians in Mesopotamia put writing in about 3000 BC, but the term "information technology" sense to talk first appeared in an article published in 1958 in the Harvard Business Review, the authors Levitt .. Whisler commented that "the new technology does not yet have the name of a created word of information technology (IT) and based on the processing techniques and storage used, it is possible to distinguish four distinct phases of development of information technology: by mechanical (3000 BC - 1450 ), mechanical (1450-1840), electromechanical (1840-1940) and electronic 1940 to the present time, this article focuses on the most recent period (e), which began in about 1940.

Programming language

2013-03-30T09:30:00.002-07:00

Programming language is a language designed to communicate instructions to the device, particularly a computer.And can be used for programming languages to create programs or games.

Programming languages used to guide the behavior of machines has been the creation of thousands of different programming languages, especially in the field of computers, with many being created every year. Description Most programming languages account inevitable manner, ie, the command sequence, although some languages, such as those that support functional programming or logic programming, and the use of alternative forms of description.

Usually is split describes the programming language to elements of the total (form) and semantics (meaning). And you know some of the languages and document specifications (for example, you select the C programming language of ISO), while the other languages, such as Perl .

Database

2013-03-30T09:21:00.001-07:00

Database is an organized collection of data.Usually data is organized to model relevant aspects of reality (availability in hospitals, for example), in a manner supportive of the processes that require this information (search for unoccupied rooms).

Database management for the purposes of public system (DBMS) is a software system designed to allow the definition, create, query, update, and manage databases. Known DBMSs include MySQL, the Internet, SQLite, and Microsoft SQL Server, Microsoft Access, Oracle, Sybase, dBASE, FoxPro, IBM and DB2. Database is not generally portable across different DBMS, but different DBMSs using standards such as SQL ODBC or JDBC

Computer network

2013-03-30T09:14:00.000-07:00

Computer network is a group of devices interconnected with each other and to exchange information with each other and share printers, files and programs are classified networks by protocols of communication between networks and scale the network structure and its benefits and scope and months networking website and can be considered as computer networks branch of electrical engineering, communications and Computer Science and information technology or computer engineering, since it relies on the theoretical and practical application of the related disciplines

Communication protocols define the rules and data formats for exchanging information in a computer network. Well-known communications protocols include Ethernet, a hardware and link layer standard that is widely used for local area networks, and the Internet protocol suite (TCP/IP), which defines a set of protocols for communication between multiple networks, for host-to-host data transfer, and for application-specific data transmission formats. Protocols provide the basis for network programming.

Microarchitecture

2013-03-30T09:01:00.000-07:00

In Computer Engineering, microarchitecture sometimes abbreviated to μarch or uarch, and it is called Computer Organization, is a way that is the implementation of the instruction set architecture (ISA) on the processor. And can be implemented ISA A given with different micro-architectures. Applications may vary because of the different goals of a particular design or because of shifts in the structure is a combination of education microarchitecture design group.

Digital electronics

2013-03-30T08:51:00.001-07:00

Digital electronics, or digital circuits (e), representing signals by separate bands of similar levels, instead of a continuous range. All levels within the same signal representing the State. Relatively small changes in the levels of analog signals due to manufacturing tolerance, signal attenuation or parasitic noise do not leave a separate envelope, and as a result are ignored by the state signal sensing circuit.

In most cases a number of these states is two, and is represented by two teams effort: one near the reference value (which is what is usually called the "ground" or volt zero) and the value near the supply voltage, corresponding to the "false" ("0") and "true" ("1") values the logical domain, respectively.

Digital techniques are useful because it is easier to get an electronic device to switch to one of a number of countries known to accurately reproduce continuous range of values.

Usually made of digital electronic circuits large associations of logic gates, simple electronic representation of Boolean logic functions

Engineering and Computer Engineering

2013-03-30T08:46:00.002-07:00

Computer engineering, computer or digital organization, is the conceptual design and fundamental operational structure of a computer system. It focuses largely on the way by which the CPU performs internally and up to addresses in memory. Often involves the disciplines in computer engineering and electrical engineering, as well as selecting and connecting hardware components to create computers that meet the technical, performance, and cost objectives.

Computer Science

2013-03-30T07:58:00.001-07:00

Computer Science or Computer Science (CS manual or Comp Sci) is the scientific and practical approach to calculate and applications. Computer scientist specializing in the theory of calculation and design of computer systems.

And can be divided into sub-fields in a variety of theoretical and practical disciplines. Some fields, such as computational complexity theory (which explores the basic characteristics of the computational problems), is very abstract, while areas such as computer graphics to emphasize real-world applications. Other areas still focus on the challenges in the implementation of the account. For example, the theory of programming language are different ways to describe the account, while the study computer programming in itself investigating various aspects of the use of the programming language and complex systems. Interaction between human and computer are the challenges in making computers and accounts are useful, usable, and universally accessible to humans