what is harddisk??? (HDD)

What is hard disk?

• A hard disk drive (HDD), commonly referred to as a hard drive, hard disk, or fixed disk drive,[1] is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk. Early HDDs had removable media; however, an HDD today is typically a sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media.[2]
• HDDs (introduced in 1956 as data storage for an IBM accounting computer[3]) were originally developed for use with general purpose computers. During the 1990s, the need for large-scale, reliable storage, independent of a particular device, led to the introduction of embedded systems such as RAID arrays, network attached storage (NAS) systems and storage area network (SAN) systems that provide efficient and reliable access to large volumes of data. In the 21st century, HDD usage expanded into consumer applications such as camcorders, cellphones, digital audio players, digital video players (e.g. the iPod Classic), digital video recorders, personal digital assistants and video game consoles.

* 1988: Tandon Corporation sold its disk manufacturing division to Western Digital (WDC), which was then a well-known controller designer.[46]
* 1989: Seagate Technology bought Control Data's high-end disk business, as part of CDC's exit from hardware manufacturing.
* 1990: Maxtor buys MiniScribe out of bankruptcy, making it the core of its low-end disk division.
* 1994: Quantum bought DEC's storage division, giving it a high-end disk range to go with its more consumer-oriented ProDrive range, as well as the DLT tape drive range.
* 1995: Conner Peripherals, which was founded by one of Seagate Technology's co-founders along with personnel from MiniScribe, announces a merger with Seagate, which was completed in early 1996.
* 1996: JTS merges with Atari, allowing JTS to bring its disk range into production. Atari was sold to Hasbro in 1998, while JTS itself went bankrupt in 1999.
* 2000: Quantum sells its disk division to Maxtor to concentrate on tape drives and backup equipment.
* 2003: Following the controversy over mass failures of its Deskstar 75GXP range, HDD pioneer IBM sold the majority of its disk division to Hitachi, who renamed it Hitachi Global Storage Technologies (HGST).
* 2003: Western Digital purchased Read-Rite Corp, which makes recording heads used on disk drive platters, for $95.4 million in cash.
* December 21, 2005: Seagate and Maxtor announced an agreement under which Seagate would acquire Maxtor in an all stock transaction valued at $1.9 billion. The acquisition was approved by the appropriate regulatory bodies, and closed on May 19, 2006.
* 2007:July: Western Digital (WDC) acquires Komag U.S.A, a thin-film media manufacturer, for USD 1 Billion
* In the year 2007 516.2 million hard disks were sold





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what is operating system?

what is operating system(os)?

• An operating system (commonly abbreviated to either OS or O/S) is an interface between hardware and applications; it is responsible for the management and coordination of activities and the sharing of the limited resources of the computer. The operating system acts as a host for applications that are run on the machine.Operating systems offer a number of services to application programs and users.
• Common contemporary operating systems include Microsoft windows, Mac os, LINUX, BSD SOLARIS. Microsoft Windows has a significant majority of market share in the desktop and notebook computer markets, while servers generally run on Linux or other Unix-like systems. Embedded device markets are split amongst several operating systems.
• it is doing Multitasking,Disk access to file systems,Virtual memory allocation,manage device drivers,networking,provide better secutiry and etc.
  

examples of operating systems and what is contains.

• Microsoft Windows:While the Windows 9x series offered the option of having profiles for multiple users, they had no concept of access privileges, and did not allow concurrent access; and so were not true multi-user operating systems. In addition, they implemented only partial memory protection. They were accordingly widely criticised for lack of security.The Windows NT series of operating systems, by contrast, are true multi-user, and implement absolute memory protection. However, a lot of the advantages of being a true multi-user operating system were nullified by the fact that, prior to Windows Vista, the first user account created during the setup process was an administrator account, which was also the default for new accounts. Though Windows XP did have limited accounts, the majority of home users did not change to an account type with fewer rights – partially due to the number of programs which unnecessarily required administrator rights – and so most home users ran as administrator all the time.
• • Windows Vista changes this[3] by introducing a privilege elevation system called User Account Control. When logging in as a standard user, a logon session is created and a token containing only the most basic privileges is assigned. In this way, the new logon session is incapable of making changes that would affect the entire system. When logging in as a user in the Administrators group, two separate tokens are assigned. The first token contains all privileges typically awarded to an administrator, and the second is a restricted token similar to what a standard user would receive. User applications, including the Windows Shell, are then started with the restricted token, resulting in a reduced privilege environment even under an Administrator account. When an application requests higher privileges or "Run as administrator" is clicked, UAC will prompt for confirmation and, if consent is given (including administrator credentials if the account requesting the elevation is not a member of the administrators group), start the process using the unrestricted token.
  
  
• Linux/Unix:Linux and UNIX both have two tier security, which limits any system-wide changes to the root user, a special user account on all UNIX-like systems. While the root user has virtually unlimited permission to affect system changes, programs running as a regular user are limited in where they can save files, what hardware they can access, etc. In many systems, a user's memory usage, their selection of available programs, their total disk usage or quota, available range of programs' priority settings, and other functions can also be locked down. This provides the user with plenty of freedom to do what needs done, without being able to put any part of the system in jeopardy (barring accidental triggering of system-level bugs) or make sweeping, system-wide changes. The user's settings are stored in an area of the computer's file system called the user's home directory, which is also provided as a location where the user may store their work, similar to My Documents on a Windows system. Should a user have to install software or make system-wide changes, they must become the root user temporarily, usually with the su or sudo command, which is answered with the computer's root password when prompted. Some systems (such as Ubuntu and its derivatives) are configured by default to allow select users to run programs as the root user via the sudo command, using the user's own password for authentication instead of the system's root password. One is sometimes said to "go root" when elevating oneself to root access.
• Mac OS X:Mac OS X supports HFS+ with journaling as its primary file system. It is derived from the Hierarchical File System of the earlier Mac OS. Mac OS X has facilities to read and write FAT, NTFS (only read, although an open-source cross plataform implementation known as NTFS 3G provides read-write support to Microsoft Windows NTFS file system for Mac OS X users.), UDF, and other file systems, but cannot be installed to them. Due to its UNIX heritage Mac OS X now supports virtually all the file systems supported by the UNIX VFS. Recently Apple Inc. started work on porting Sun Microsystem's ZFS filesystem to Mac OS X and preliminary support is already available in Mac OS X 10.5.
  

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What is hardware in that MOTHERBOARD...

what is hardware?
A personal computer is made up of computer hardware,multiple physical components on to which can be loaded into a multitude of software that perform the function of the computer.

Motherboard

• motherboard - It is the "body" or mainframe of the computer, through which all other components interface.
• central processing unit (CPU) - Performs most of the calculations which enable a computer to function, sometimes referred to as the "backbone" or "brain" of the computer.
  • computer fan- Used to lower the temperature of the computer; a fan is almost always attached to the CPU, and to the back of the case, also known as the 'muffin fan'.
• firmware is system specific read only memory.
• Internal buses - Connections to various internal components.
  • Current
    • PCI (being phased out for graphic cards but still used for other uses)
    • PCI Express (PCI-E)
    • USB
      
    • FIREWIRE
      
    • HYPER TRANSPORT
      
    • INTEL QUICK PATH (expected in 2008)
  • Obsolete
    • AGP (obsolete graphic card bus)
    • ISA(obsolete in PCs, but still used in industrial computers)
    • VLB VESA Local Bus (outdated)
• External Bus Controllers - used to connect to external peripherals, such as printers and input devices. These ports may also be based upon expansion cards, attached to the internal motherboard.

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What is software?

the most common question the people who are not more attached with computer world.
so we are here just try to clear their doubts related to software...

software is a general term used to describe a collection of computer programs,procedures and documentation that perform some task on a computer system.
in sort words we can say that software is used to manage the hardware.

Basically there are three types of softwares.
1).System software
2).Programming software
3).application software



*system software helps to run the computer hardware and
computer system.like device drivers and utilities.
*Programming software usually provides tools to assist a programmer in writing computer programs and softwares using different programming languages.like compilers.
*Application software is used to accomplished some task or some works which is based on using softwares.like word processor ETC.

executable softwares are mainly in windows computers comes with .exe extension.

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• DISCLAIMER:
• THIS ALL THE DATA IN FROM WHICH WE FATCH IS ONLY FOR THE LEARNING PURPOSE ONLY AND IT ARE RESPECTIVE RIGHT OF THEIR OWNERS.
• HERE PICTURES ARE TAKEN FROM WIKIPEDIA.ORG.