Monday, March 14, 2011

Local Area Network (LAN)

A local area network (LAN) is a computer network that connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.

ARCNET, Token Ring and other technology standards have been used in the past, but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently in use.

As larger universities and research labs obtained more computers during the late 1960s, there was an increasing pressure to provide high-speed interconnections. A report in 1970 from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gives a good indication of the situation.

Cambridge Ring was developed at Cambridge University in 1974 but was never developed into a successful commercial product.

Ethernet was developed at Xerox PARC in 1973–1975, and filed as U.S. Patent 4,063,220. In 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper, "Ethernet: Distributed Packet-Switching For Local Computer Networks."

ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977. It had the first commercial installation in December 1977 at Chase Manhattan Bank in New York.

The development and proliferation of CP/M-based personal computers from the late 1970s and then DOS-based personal computers from 1981 meant that a single site began to have dozens or even hundreds of computers. The initial attraction of networking these was generally to share disk space and laser printers, which were both very expensive at the time. There was much enthusiasm for the concept and for several years, from about 1983 onward, computer industry pundits would regularly declare the coming year to be “the year of the LAN”.

In practice, the concept was marred by proliferation of incompatible physical Layer and network protocol implementations, and a plethora of methods of sharing resources. Typically, each vendor would have its own type of network card, cabling, protocol, and network operating system. A solution appeared with the advent of Novell NetWare which provided even-handed support for dozens of competing card/cable types, and a much more sophisticated operating system than most of its competitors. Netware dominated the personal computer LAN business from early after its introduction in 1983 until the mid 1990s when Microsoft introduced Windows NT Advanced Server and Windows for Workgroups.

Of the competitors to NetWare, only Banyan Vines had comparable technical strengths, but Banyan never gained a secure base. Microsoft and 3Com worked together to create a simple network operating system which formed the base of 3Com's 3+Share, Microsoft's LAN Manager and IBM's LAN Server - but none of these were particularly successful.

During the same period, Unix computer workstations from vendors such as Sun Microsystems, Hewlett-Packard, Silicon Graphics, Intergraph, NeXT and Apollo were using TCP/IP based networking. Although this market segment is now much reduced, the technologies developed in this area continue to be influential on the Internet and in both Linux and Apple Mac OS X networking—and the TCP/IP protocol has now almost completely replaced IPX, AppleTalk, NBF, and other protocols used by the early PC LANs.

Tuesday, March 8, 2011

List of Microsoft Windows versions

This page lists and links to information on the various versions of Microsoft Windows, a major computer operating system developed by Microsoft.
  • Windows 7, for home and business desktops and portable computers
    • Windows 7 Starter A variant for developing countries and netbooks, in which the Aero theme is not included, nor 64-bit compatibility. This edition will be available pre-installed on computers through system integrators or computer manufacturers.
    • Windows 7 Home Basic Windows 7 Home Basic will be available in emerging markets such as Brazil, People's Republic of China, India, Indonesia, Mexico, Pakistan, the Philippines, and Thailand. It will not be available in countries such as Australia, Canada, France, Germany, The Netherlands, United Arab Emirates, Saudi Arabia, New Zealand, the United States, and the United Kingdom. Some Aero options are excluded along with several new features.
    • Windows 7 Home Premium This edition contains features aimed at the home market segment, such as Windows Media Center, Windows Aero and touch-screen controls.
    • Windows 7 Professional This edition is targeted toward enthusiasts and small business users. It includes all the features of Windows 7 Home Premium, and adds the ability to participate in a Windows Server domain. Additional features include operating as a Remote Desktop server, location aware printing, Encrypting File System, Presentation Mode and Windows XP Mode.
    • Windows 7 Enterprise (Microsoft Windows NT 6.1.7600) This edition targets the enterprise segment of the market and will be sold through volume licensing to companies which have Software Assurance contract with Microsoft. Additional features include support for Multilingual User Interface (MUI) packages, BitLocker Drive Encryption, and UNIX application-support. Not available through retail or OEM channels, this edition will be distributed through Microsoft Software Assurance (SA). As a result it includes several SA-only benefits, including a license allowing the running of multiple virtual machines, and activation via VLK.
    • Windows 7 Ultimate Windows 7 Ultimate contains the same features as Windows 7 Enterprise, but unlike that edition it will be available to home users on an individual license basis. Windows 7 Home Premium and Windows 7 Professional users will be able to upgrade to Windows 7 Ultimate for a fee using Windows Anytime Upgrade if they wish to do so. Unlike Windows Vista Ultimate, the Windows 7 Ultimate edition will not include the Windows Ultimate Extras feature or any exclusive features. (6.1.7600)
  • Windows Server 2008 R2 for servers.
  • Windows Web Server 2008 R2
  • Windows Storage Server 2008 R2
  • Windows Server 2008 R2 Standard Edition
  • Windows Server 2008 R2 Enterprise Edition
  • Windows Server 2008 R2 Datacenter Edition
  • Windows Server 2008 R2 for Itanium-based Systems
  • Windows HPC Server 2008 R2 for high Performance supercomputers
  • Windows Server 2008 R2 Foundation
  • Windows Mobile 6.5 for smartphones and PDAs
  • Windows Home Server Announced at the 2007 Consumer Electronics Show (CES) in Las Vegas. Windows Home Server is intended to be a solution for homes with multiple connected PCs to offer file sharing, automated backups, and remote access.
  • Windows XP Embedded, for embedded systems requiring parts of the Windows XP infrastructure
  • Windows Fundamentals for Legacy PCs, a low-end version of Windows XP that is intended to be a thin-client that works with older hardware.
  • Windows Embedded CE 6.0, for embedded systems (not based on the Windows NT kernel)

Past versions

  • Windows Mobile 6.1 for smartphones and PDAs
  • Windows Server 2008 for servers.
    • Windows Web Server 2008
    • Windows Server 2008 Standard Edition
    • Windows Server 2008 Enterprise Edition (Microsoft Windows NT 6.0.6001 Service Pack 1)
    • Windows Server 2008 Datacenter Edition
    • Windows Storage Server 2008
    • Windows Small Business Server 2008 (Codenamed "Cougar") for small businesses
    • Windows Essential Business Server 2008 (Codenamed "Centro") for medium-sized businesses
    • Windows Server 2008 for Itanium-based Systems
    • Windows HPC Server 2008 for high Performance supercomputers
    • Windows Server Foundation 2008
  • Windows Vista, for home and business desktops and portable computers
    • Windows Vista Starter Similar to Windows XP Starter Edition, this edition will be limited to emerging markets such as Colombia, India, Thailand, and Indonesia, mainly to offer a legal alternative to using unauthorized copies. It will not be available in the United States, Canada, Europe, or Australia.
    • Windows Vista Home Basic Similar to Windows XP Home Edition, Home Basic is intended for budget users not requiring advanced media support for home use. The Windows Aero theme with translucent effects will not be included with this edition.
    • Windows Vista Home Premium Like Windows XP Media Center Edition, this edition will support more advanced multimedia and entertainment authoring, premium games, mobile and tablet PC support, Network Projector, Windows Aero, Touch Screen, and auxiliary display (via Windows Side Show) support.
    • Windows Vista Business This edition is aimed at the business market. It includes advanced network and security features, whilst excluding entertainment features.
    • Windows Vista Enterprise (Microsoft Windows NT 6.0.6000.0) This edition is aimed at the enterprise segment of the market, and is a superset of the Business edition. Additional features include multilingual user interface support, BitLocker Drive Encryption, and UNIX application support. This edition will not be available through retail or OEM channels
    • Windows Vista Ultimate This edition combines all the features of the Home Premium and Enterprise editions, a game performance tweaker (WinSAT), and "Ultimate Extras".
  • Windows Server 2003 for servers
    • Small Business Server for first server installations (up to 2 processors)
    • Web Edition for basic Web serving (up to 2 processors)
    • Standard Edition for smaller server applications that don't require clustering (up to 4 processors)
    • Enterprise Edition for larger server applications, and clustering (up to 8 processors)
    • Datacenter Edition for mainframe like servers (up to 128 processors)
    • Storage Server for Network Attached Storage Devices (5.2.3790)
  • Windows Mobile 6 for smartphones and PDA
    • Windows Mobile 6 Standard for smartphones
    • Windows Mobile 6 Classic for PDA without GSM
    • Windows Mobile 6 for PDA with GSM
  • Windows XP for desktops and laptops (notebooks)
    • Windows XP Starter Edition, for new computer users in developing countries
    • Windows XP Home Edition, for home desktops and laptops
    • Windows XP Home Edition N, as above, but without a default installation of Windows Media Player, as mandated by an EU ruling
    • Windows XP Professional, for business and power users (Version number: NT 5.1.2600)
    • Windows XP Professional N, as above, but without a default installation of Windows Media Player, as mandated by an EU ruling
    • Windows XP Professional x64 Edition, for PCs with x86-64 processors (based on Windows Server 2003)
    • Windows XP Tablet PC Edition, for notebooks with a touch screen or a pen-sensitive screen
    • Windows XP Media Center Edition for desktops and notebooks with an emphasis on audio, video, and PVR capability. There are four versions:
      • Windows XP Media Center Edition
      • Windows XP Media Center Edition 2003
      • Windows XP Media Center Edition 2004
      • Windows XP Media Center Edition 2005
    • 2001 October 25 - Windows XP 64-bit Edition - A version of Windows XP roughly analogous to Windows XP Professional for Intel's IA-64 (Itanium) line of CPUs. It was discontinued in early 2005 after manufacturers stopped shipping Itanium systems marketed as 'workstations'.
    • Windows XP Tablet PC Edition, for tablet PCs
  • 2000 February 17 - Windows 2000 (Version number: NT 5.0.2195)
    • Windows 2000 Professional
    • Windows 2000 Server
    • Windows 2000 Advanced Server
    • Windows 2000 Datacenter Server
  • 2000 June 19 - Windows Me (Version number: 4.90.3000 (Security Version 4.90.3000A))
  • Windows 98
    • 1999 May 5 - Windows 98 Second Edition (Version number: 4.10.2222 or 4.10.2222A (Security Version 4.10.2222C))
    • 1998 June 25 - Windows 98 (Version number: 4.10.1998 (Security Version 4.10.1998A))
  • 1996 July 29 - Windows NT 4.0 - the last version which ran on RISC architectures like DEC Alpha, MIPS and PowerPC. Later versions concentrated on x86-based hardware and - mainly as server OSs - the IA-64 line of CPUs. (Version number: NT 4.0.1381)
  • Windows 95
    • 1997 November 26 - Windows 95 OSR2.5 (Version number: 4.03.1216 (also listed as 4.00.950C))
    • 1997 August 27 - Windows 95 OSR 2.1 (Version number: 4.03.1214 (also listed as 4.00.950B))
    • 1997 August 27 - Windows 95 USB Supplement to OSR2 (Version number: 4.03.1212 (also listed as 4.00.950B))
    • 1996 August 24 - Windows 95 OSR2 (Version number: 4.00.1111 (also listed as 4.00.950B))
    • 1996 February 14 - Windows 95 OSR1 (Version number: 4.00.951 (also listed as 4.00.950A)
    • 1995 December 31 - Windows 95 SP1 (Version number: 4.00.951 (also listed as 4.00.950A)
    • 1995 August 24 - Microsoft Plus! for Windows 95 (Version number: 4.40.310)
    • 1995 August 24 - Windows 95 (Version number: 4.00.950)
  • 1995 June - Windows NT 3.51 (Version number: NT 3.51.1057)
  • 1994 September - Windows NT 3.5 (Version number: NT 3.50.807)
  • 1993 November - Windows for Workgroups 3.11
  • 1993 October - Windows 3.2 This Version of Windows was only released in simplified Chinese.
  • 1993 August - Windows NT 3.1 (Version number: NT 3.10.528)
  • 1992 October - Windows for Workgroups 3.1
  • 1992 August - Windows 3.1 (Version number: 3.10.040)
  • 1990 May 22 - Windows 3.0 (Version number: 3.00.73)
  • 1989 March 13 - Windows 2.11
  • 1988 May 27 - Windows 2.10
  • 1987 December 9 - Windows 2.03
  • 1987 April - Windows 1.04
  • 1986 August - Windows 1.03
  • 1986 May - Windows 1.02
  • 1985 November 20 - Windows 1.01
  • CE-based
    • 2008 Windows Mobile 6.1, based on Windows CE 5.2.19202
    • 2006 Windows CE 6.0
    • 2005 Windows CE 5.0, with version for smart phones and PDAs sold as Windows Mobile 5.0
    • 2004 Windows CE 4.2, with version for smart phones and PDAs sold as Windows Mobile 2003 SE
    • 2003 Windows CE 4.1, with version for smart phones and PDAs sold as Pocket PC 2003
    • 2002 Windows CE 4.0, with version for smart phones and PDAs sold as Pocket PC 2002
    • 2000 July - Windows CE 3.0, with version for smart phones and PDAs sold as Pocket PC 2000
    • 1999 August - Windows CE 2.12
    • 1998 October - Windows CE 2.11
    • 1998 July - Windows CE 2.1
    • 1997 November - Windows CE 2.0
    • 1996 November - Windows CE 1.0

History of Microsoft Windows

Microsoft has taken two parallel routes in its operating systems. One route has been for the home user and the other has been for the professional IT user. The dual routes have generally led to home versions having greater multimedia support and less functionality in networking and security, and professional versions having inferior multimedia support and better networking and security.

The first version of Microsoft Windows, version 1.0, released in November 1985, lacked a degree of functionality and achieved little popularity, and was to compete with Apple’s own operating system. Windows 1.0 is not a complete operating system; rather, it extends MS-DOS. Microsoft Windows version 2.0 was released in November 1987 and was slightly more popular than its predecessor. Windows 2.03 (release date January 1988) had changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights.

Microsoft Windows version 3.0, released in 1990, was the first Microsoft Windows version to achieve broad commercial success, selling 2 million copies in the first six months. It featured improvements to the user interface and to multitasking capabilities. It received a facelift in Windows 3.1, made generally available on March 1, 1992. Windows 3.1 support ended on December 31, 2001.

In July 1993, Microsoft released Windows NT based on a new kernel. Windows NT 3.1 was the first release of Windows NT. NT was considered to be the professional OS and was the first Windows version to utilize preemptive multitasking. Windows NT would later be retooled to also function as a home operating system, with Windows XP.

On August 24, 1995, Microsoft released Windows 95, a new, and major, consumer version that made further changes to the user interface, and also used preemptive multitasking. Windows 95 was designed to replace not only Windows 3.1, but also Windows for Workgroups, and MS-DOS. It was also the first Windows operating system to use Plug and Play capabilities. The changes Windows 95 brought to the desktop were revolutionary, as opposed to evolutionary, such as those in Windows 98 and Windows Me. Mainstream support for Windows 95 ended on December 31, 2000 and extended support for Windows 95 ended on December 31, 2001.

The next in the consumer line was Microsoft Windows 98 released on June 25, 1998. It was followed with the release of Windows 98 Second Edition (Windows 98 SE) in 1999. Mainstream support for Windows 98 ended on June 30, 2002 and extended support for Windows 98 ended on July 11, 2006.

As part of its "professional" line, Microsoft released Windows 2000 in February 2000. During 2004 part of the Source Code for Windows 2000 was leaked onto the Internet. This was bad for Microsoft as the same kernel used in Windows 2000 was used in Windows XP. The consumer version following Windows 98 was Windows Me (Windows Millennium Edition). Released in September 2000, Windows Me implemented a number of new technologies for Microsoft: most notably publicized was "Universal Plug and Play". Windows Me was heavily criticized due to slowness, freezes and hardware problems.

In October 2001, Microsoft released Windows XP, a version built on the Windows NT kernel that also retained the consumer-oriented usability of Windows 95 and its successors. This new version was widely praised in computer magazines. It shipped in two distinct editions, "Home" and "Professional", the former lacking many of the superior security and networking features of the Professional edition. Additionally, the first "Media Center" edition was released in 2002, with an emphasis on support for DVD and TV functionality including program recording and a remote control. Mainstream support for Windows XP ended on April 14, 2009. Extended support will continue until April 8, 2014.

In April 2003, Windows Server 2003 was introduced, replacing the Windows 2000 line of server products with a number of new features and a strong focus on security; this was followed in December 2005 by Windows Server 2003 R2.

On January 30, 2007, Microsoft released Windows Vista. It contains a number of new features, from a redesigned shell and user interface to significant technical changes, with a particular focus on security features. It is available in a number of different editions, and has been subject to some criticism.

On October 22, 2009, Microsoft released Windows 7. Unlike its predecessor, Windows Vista, which introduced a large number of new features, Windows 7 was intended to be a more focused, incremental upgrade to the Windows line, with the goal of being compatible with applications and hardware which Windows Vista was not at the time. Windows 7 has multi-touch support, a redesigned Windows shell with a new taskbar, referred to as the Superbar, a home networking system called HomeGroup, and performance improvements.

Microsoft Windows


Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Microsoft Windows came to dominate the world's personal computer market, overtaking Mac OS, which had been introduced in 1984. As of October 2009, Windows had approximately 91% of the market share of the client operating systems for usage on the Internet. The most recent client version of Windows is Windows 7; the most recent server version is Windows Server 2008 R2; the most recent mobile OS version is Windows Phone 7.

Windows Registry

The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user interface and third party applications all make use of the Registry. The registry also provides a means to access counters for profiling system performance.

When first introduced with Windows 3.1, the Windows registry's primary purpose was to store configuration information for COM-based components. With the introduction of Windows 95 and Windows NT, its use was extended to tidy up the profusion of per-program INI files that had previously been used to store configuration settings for Windows programs.

.INI files stored each program's settings into a text file, often located in a shared location that did not allow for user-specific settings in a multi-user scenario. By contrast, the Windows registry stores all application settings in one central repository and in a standardized form. This offers several advantages over INI files. Since accessing the registry does not require parsing, it may be read from or written to more quickly than an INI file. As well, strongly-typed data can be stored in the registry, as opposed to the text information stored in INI files. Because user-based registry settings are loaded from a user-specific path rather than from a read-only system location, the registry allows multiple users to share the same machine, and also allows programs to work for less privileged users. Backup and restoration is also simplified as the registry can be accessed over a network connection for remote management/support, including from scripts, using the standard set of APIs, as long as the Remote Registry service is running and firewall rules permit this.

The registry has features that improve system integrity, as the registry is constructed as a database and offers database-like features such as atomic updates. If two processes attempt to update the same registry value at the same time, one process's change will precede the other's and the overall consistency of the data will be maintained. Where changes are made to INI files, such race conditions can result in inconsistent data which doesn't match either attempted update. Windows Vista and Windows 7 provide transactional updates to the registry, extending the atomicity guarantees across multiple key and/or value changes, with traditional commit-abort semantics. (Note however that NTFS provides such support for the file system as well, so the same guarantees could, in theory, be obtained with traditional configuration files.)

While offering improvements over application-specific .INI files, the organization and implementation of the registry also had potential problems:
  • The registry duplicates much of the functionality of the file system.
  • Centralizing configurations makes it more difficult to back up and recover individual applications.
  • Installers and uninstallers may become more complicated if applications rely on Registry configuration settings that need to be created by installation applications because these Registry settings cannot be transferred by simply copying the application files that comprise the application. Use of the Registry by non-COM based applications is optional; .Net applications leverage a configuration file instead of the Registry. Some other operating systems (e.g., OS X) also support installation through simple file copy.
  • Because information required for loading device drivers is stored in the registry,a damaged System registry may prevent a Windows system from booting successfully, since some device drivers won't be loaded, preventing the affected devices from working.[dubious – discuss] Device drivers are stored in a key called HKLM\System\CurrentControlSet, which is a symbolic link that alternates between HKLM\System\CurrentControlSet001 and HKLM\System\CurrentControlSet002, thereby allowing the "last known configutation" boot option to provide a mechanism of reverting to the last configutation that successfully started the system.
  • The parts of the registry may have to be kept in sync with the file system (e.g., deleting an application rather than uninstalling it, may leave associated configuration items such as COM registration entries in the registry if the application is legacy and does not leverage side-by-side registry-free configuration.[5])
  • Applications that make use of the registry to store and retrieve their settings may be unsuitable for use on portable devices used to carry applications from one system to another. Similarly, it is often not possible to copy installed applications that use the Registry to another computer. This means that software usually has to be reinstalled from original media after a computer upgrade or rebuild. Application virtualization addresses this problem.
  • The Windows Registry is claimed by some third parties to be a single point of failure.

source: wikipedia.org

Sunday, March 6, 2011

Types of Operating Systems

Types of Operating Systems :

Real-time Operating System: It is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based on their priorities while time-sharing operating systems switch tasks based on clock interrupts.

Multi-user and Single-user Operating Systems: The operating systems of this type allow a multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system.

Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run at a time, the system is grouped under a single-tasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types namely, pre-emptive or co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. MS Windows prior to Windows 95 used to support cooperative multitasking.

Distributed Operating System: An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each other, gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.

Embedded System: The operating systems designed for being used in embedded computer systems are known as embedded operating systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems.

Operating System

An operating system (OS) is software, consisting of programs and data, that runs on computers and manages computer hardware resources and provides common services for efficient execution of various application software.

For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between application programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently call the OS or be interrupted by it. Operating systems are found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Examples of popular modern operating systems for personal computers are (in alphabetical order): GNU/Linux, Mac OS X, Microsoft Windows and Unix.

Thursday, March 3, 2011

Using Computer Correctly

As stated before, componen of computer include hardware, software, and brain ware. The kind of computer we often use is PC (personal computer). Usualy, a PC consists of hardware including one unit of CPU, input devises  in form of mouse and keyboard, and output device like monitor. Those are minimum harrdware that computer can be operated. Sometimes, additional devices like printer for printing data on copy like paper, stabilizer fir stabilizing voltage and speaker for output device producing sound may be required. To be operable, a computer must be completed with software including operating system and application programs.

Other significant component other than hardware and software is brain ware. A computer will provide with optimal benefits if the user has sufficient knowledge and capability to operate the computer.

History of Computer

The history of computer started in 1940, namely by invention of first electronic computer on the wordl know as ABC (Atanasoff and Berry Computer) taken from names of its invertor. In the same decade, Dr. John W M. Maunchly with J. Presper Eckert, Jr., invented a kind of computer knows as ENIAC (Electronic Numerical Integrator Anda Computer) It is made for calculating tables of bullet trajectories for US army. ENIAC was thousands faster than provious electromechanical computer, indicating a heap in computer technology. Weight of ENIAC reached 30 tons and required a room in size of 1,800 squarefeet (167m2). By total 18,000 vacuum tubes, ENIAC required great amount of electric power, reaching 174 kilowatts that there was a joke at that time "If ENIAC is turned on, all lamps in Philadelphia would turn off".


Computer invented in this time called first-generation computer. At that time, computer employed vacuum tubes as signal strengthener. The vacum tubes were made of glass that their weaknesses were fragile and easy to transfer heat. This heat was neutralized by using other component as a cooler. It was why ENIAC had sch a big size.

Impracticality of ENIAC supported scientist to develop electronic computer. Nowadays, transitor's invention has been sign for second-generation computer (1959-1964). Transistor has been a substitute for vacuum tubes for amplifying signal. Transistor has many advantages than vacuum tubes like non-fragile and non-heat conductor so that this second-generation computer had better capabilities, trustable, cheaper and as well as place saving. In 1960s, IBM introduced commercial computer using transistor and used widely, namely IBM-7090. Other second-generation computer was IBM series 1400, NCR 304, PDP-8, and Mark IV.

Several people state that 1971 was the beginning of fourth-generation computer by introducing microprocessor as integration of thousands of ICs into a chip. Its form became much smaller with increasing capability and cheaper price. Microprocessor is the beginning of PC (personal computer) invention. Microprocessor series 4004 by Intel Corp.

Tuesday, March 1, 2011

Defenition of Computer

Literally, the term "computer" is derived from "compute" meaning calculate. Perhaps, in follows initial objective of creating computer, namely hoe create an adding a=machine capable to do many calculations accurately. However, during its development, this machine changes to be multipurpose machine, not only for calculating only. Computer has developed to be versatile machine that may change functions based on necessities. Sometimes, it is used as typewriter, calculator, drawing creator, song and film player, etc.

Computer means a series a group electronic machines consiting of thousands even millions of components able to cooperate and to form an order and thorough work system. This system can then be used to carry out a series of tasks automatically based on order of instructions or programs made for it. A group electronic machines means hardware of computer. Hardware can defined as physical sets equipment since it is visible, touchable, and movable. Solely relying on hardware will run the computer. Computer requires a program installed into to. This program can be in form of a operations from the computer itself or a procedure in case of processing data as previosly provided. These program are called software of a computer.

Principally, computer is only an intrument. It can be used to assist human being in finishing tasks. For working, the instrument requires program and human. Definition of human being is then knows as brain ware (human instrument). Defenition of brain ware may include people directly working by using computeras auxiliary tools and people working indirectly by using computer but receiving of computer in form of report.

Concept of hardware-software-brain ware is trinity concept inseparable one another. Firtly, human must install program to computer will star working for assisting human being solve problem and finish duties.

Basic Operation of Computer

Computer is not strange anymore in this era. You can find it in houses, schools, and offices easily. Moreover, computer has become basic need for several people. 


From time to time, communication holds vital role for human life. May be, we can make it equal to basic needs like food, clothes, or home. As we know, human being is a social creature requiring other for survival. For interaction with others, human needs tools, instrument, or method of communication. Thus, anything related to communication is very significant for human life.

One of the most sifnificant equipment in communication development is computer. This device can be directly used as communication and exchanging information tools or may support other communication tools. We can send letters or make direct conversation using computer connected to networks or internet. Computer is also used for procesing data and information. Thus, it is a must for us to be capable in operating computer, both as information processor and communication tool (information exchange itself). 

 
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