LINUX

Linux 
 (commonly pronounced /ˈlɪnəks/ LIN-əks in American English,^[4][5] also pronounced /ˈlɪnʊks/ LIN-ooks^[6] in Europe and Canada) refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers.^{[7][8][9][10]} Linux is predominantly known for its use in servers; in 2009 it held a server market share ranging between 20–40%. Most desktop computers run either Microsoft Windows or Mac OS X, with Linux having anywhere from a low of an estimated 1–2% of the desktop market to a high of an estimated 4.8%.^[11] However, desktop use of Linux has become increasingly popular in recent years, partly owing to the popular Ubuntu, Fedora, Mint, and openSUSE distributions^[12] and the emergence of netbooks and smartphones running an embedded Linux.^[13][14]
The development of Linux is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License. Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Linux distributions include the Linux kernel and all of the supporting software required to run a complete system, such as utilities and libraries, the X Window System, the GNOME and KDE desktop environments, and the Apache HTTP Server. Commonly used applications with desktop Linux systems include the Mozilla Firefox web-browser, the OpenOffice.org office application suite and the GIMP image editor.
The name "Linux" comes from the Linux kernel, originally written in 1991 by Linus Torvalds. The main supporting user space system tools and libraries from the GNU Project (announced in 1983 by Richard Stallman) are the basis for the Free Software Foundation's preferred name GNU/Linux

Ubuntu

Ubuntu
It is named after the Southern African ethical principle Ubuntu ("humanity towards others").^[7] Ubuntu provides an up-to-date, stable operating system for the average user, with a strong focus on usability and ease of installation. Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50%,^[8][9] and upward trending usage as a web server.^[10]
Ubuntu is composed of many software packages, of which the vast majority are distributed under a free software license (also known as open source). The main license used is the GNU General Public License (GNU GPL) which, along with the GNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. Ubuntu is sponsored by the UK-based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. By keeping Ubuntu free and open source, Canonical is able to utilize the talents of community developers in Ubuntu's constituent components. Instead of selling Ubuntu for profit, Canonical creates revenue by selling technical support and from creating several services tied to Ubuntu.
Canonical endorses and provides support for three additional Ubuntu-derived operating systems: Kubuntu, Edubuntu, also known as Ubuntu Education Edition, and Ubuntu Server Edition. There are several other derivative operating systems including local language and hardware-specific versions.^[11]
Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. LTS (Long Term Support) versions, which are released every two years,^[12] are supported for three years on the desktop and five years for servers.^[13] The latest version of Ubuntu, 10.04 (Lucid Lynx), is such an LTS version, and was released on April 29, 2010.

Proccesor

The processor 

(CPU, for Central Processing Unit) is the computer's brain. It allows the processing of numeric data, meaning information entered in binary form, and the execution of instructions stored in memory.

The first microprocessor (Intel 4004) was invented in 1971. It was a 4-bit calculation device with a speed of 108 kHz. Since then, microprocessor power has grown exponentially. So what exactly are these little pieces of silicone that run our computers?

Random-access memory (RAM)

Random-access memory (RAM)

is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order (i.e., at random). "Random" refers to the idea that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data.^[1]
By contrast, storage devices such as magnetic discs and optical discs rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than data transfer, and the retrieval time varies based on the physical location of the next item.
The word RAM is often associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off. Many other types of memory are RAM, too, including most types of ROM and a type of flash memory called NOR-Flash.

CD-ROM

CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback, the 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data.^[2]
CD-ROMs are popularly used to distribute computer software, including games and multimedia applications, though any data can be stored (up to the capacity limit of a disc). Some CDs hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). These are called enhanced CDs.
Although many people use lowercase letters in this acronym, proper presentation is in all capital letters with a hyphen between CD and ROM. At the time of the technology's introduction it had more capacity than computer hard drives common at the time. The reverse is now true, with hard drives far exceeding CDs, DVDs and Blu-ray, though some experimental descendants of it such as HVDs may have more space and faster data rates than today's biggest hard drive.

CD-ROM format A CD-ROM sector contains 2,352 bytes, divided into 98 24-byte frames. Unlike a music CD, a CD-ROM cannot rely on error concealment by interpolation, and therefore requires a higher reliability of the retrieved data. In order to achieve improved error correction and detection, a CD-ROM has a third layer of Reed–Solomon error correction.^[4] A Mode-1 CD-ROM, which has the full three layers of error correction data, contains a net 2,048 bytes of the available 2,352 per sector. In a Mode-2 CD-ROM, which is mostly used for video files, there are 2,336 user-available bytes per sector. The net byte rate of a Mode-1 CD-ROM, based on comparison to CDDA audio standards, is 44100 Hz × 16 bits/sample × 2 channels × 2,048 / 2,352 /8 = 153.6 kB/s = 150 KiB/s. The playing time is 74 minutes, or 4,440 seconds, so that the net capacity of a Mode-1 CD-ROM is 682 MB or, equivalently, 650 MiB.

A 1× speed CD drive reads 75 consecutive sectors per second.

mother board ( main board)

If you've ever taken the case off of a computer, you've seen the one piece of equipment that ties everything together -- the motherboard. A motherboard allows all the parts of your computer to receive power and communicate with one another.
­­­Motherboards have come a long way in the­ last twenty years. The first motherboards held very few actual components. The first IBM PC motherboard had only a processor and card slots. Users plugged components like floppy drive controllers and memory into the slots.

Today, motherboards typically boast a wide variety of built-in features, and they directly affect a computer's capabilities and potential for upgrades.
In this article, we'll look at the general components of a motherboard. Then, we'll closely examine five points that dramatically affect what a computer can do.

personal computer

A personal computer (PC) is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user with no intervening computer operator. This is in contrast to the batch processing or time-sharing models which allowed large expensive mainframe systems to be used by many people, usually at the same time, or large data processing systems which required a full-time staff to operate efficiently.
A personal computer may be a desktop computer, a laptop, a tablet PC, or a handheld PC (also called a palmtop). The most common microprocessors in personal computers are x86-compatible CPUs. Software applications for personal computers include word processing, spreadsheets, databases, Web browsers and e-mail clients, games, and myriad personal productivity and special-purpose software applications. Modern personal computers often have high-speed or dial-up connections to the Internet allowing access to the World Wide Web and a wide range of other resources.
A PC may be used at home or in an office. Personal computers may be connected to a local area network (LAN), either by a cable or a wireless connection.
While early PC owners usually had to write their own programs to do anything useful with the machines, today's users have access to a wide range of commercial and non-commercial software, which is provided in ready-to-run or ready-to-compile form. Since the 1980s, Microsoft and Intel have dominated much of the personal computer market with the Wintel platform.