Hamster

Hamster: This lively pet hamster will keep you company throughout the day. Watch him run on his wheel, drink water, and eat the food you feed him by clicking your mouse. Click the center of the wheel to make him get back on it.

Microsoft Windows

In 1983 Microsoft announced the development of Windows, a graphical user interface (GUI) for its own operating system (MS-DOS), which had shipped for IBM PC and compatible computers since 1981. Since then, Microsoft has shipped many versions of Windows, and the product line has changed from a GUI product to a modern operating system.

Windows 95

• Windows 95 - original release
  
• Windows 95 A - included Windows 95 OSR1 slipstreamed into the installation.
  
• Windows 95 B - (OSR2) included several major enhancements, Internet Explorer (IE) 3.0 and full FAT32 file system support.
  
• Windows 95 B USB - (OSR2.1) included basic USB support.
  
• Windows 95 C - (OSR2.5) included all the above features, plus IE 4.0. This was the last 95 version produced.
  OSR2, OSR2.1, and OSR2.5 were not released to the general public, rather, they were available only to OEMs that would preload the OS onto computers. Some companies sold new hard drives with OSR2 preinstalled (officially justifying this as needed due to the hard drive's capacity).
  The first Microsoft Plus! add-on pack was sold for Windows 95.

Windows 98

On 25 June 1998, Microsoft released Windows 98, which was widely regarded as a minor revision of Windows 95, but generally found to be more stable and reliable than its 1995 predecessor. It included new hardware drivers and better support for the FAT32 file system which allows support for disk partitions larger than the 2 GB maximum accepted by Windows 95. The USB support in Windows 98 is far superior to the token, unreliable support provided by the OEM editions of Windows 95. It also controversially integrated the Internet Explorer browser into the Windows GUI and Windows Explorer file manager, prompting the opening of the United States v. Microsoft case, dealing with the question of whether Microsoft was abusing its hold on the PC operating system market to unfairly compete with companies such as Netscape.
In 1999, Microsoft released Windows 98 Second Edition, an interim release whose most notable feature was the addition of Internet Connection Sharing, which was a form of network address translation, allowing several machines on a LAN (Local Area Network) to share a single Internet connection. Hardware support through device drivers was increased. Many minor problems present in the original Windows 98 were found and fixed which make it, according to many, the most stable release of Windows 9x family.

Windows 2000

Microsoft released Windows 2000, known during its development cycle as Windows NT 5.0, in February 2000. It was successfully deployed both on the server and the workstation markets. Amongst Windows 2000's most significant new features was Active Directory, a near-complete replacement of the NT 4.0 Windows Server domain model, which built on industry-standard technologies like DNS, LDAP, and Kerberos to connect machines to one another. Terminal Services, previously only available as a separate edition of NT 4, was expanded to all server versions. A number of features from Windows 98 were incorporated as well, such as an improved Device Manager, Windows Media Player, and a revised DirectX that made it possible for the first time for many modern games to work on the NT kernel. Windows 2000 is also the last NT-kernel Windows operating system to lack Product Activation.
While Windows 2000 upgrades were available for Windows 95 and Windows 98, it was not intended for home usersIt lacked device drivers for many common consumer devices such as scanners and printers.

Windows 2000 was available in six editions:

• Windows 2000 Professional
  
• Windows 2000 Server
  
• Windows 2000 Advanced Server
  
• Windows 2000 Datacenter Server
  
• Windows 2000 Advanced Server Limited Edition
  
• Windows 2000 Datacenter Server Limited Edition

Windows Millennium Edition (Me)

In September 2000, Microsoft introduced Windows Me (Millennium Edition), which upgraded Windows 98 with enhanced multimedia and Internet features. It also introduced the first version of System Restore, which allowed users to revert their system state to a previous "known-good" point in the case of system failure. System Restore was a notable feature that made its way into Windows XP. The first version of Windows Movie Maker was introduced as well.
Windows Me was conceived as a quick one-year project that served as a stopgap release between Windows 98 and Windows XP. Many of the new features were available from the Windows Update site as updates for older Windows versions, (System Restore and Windows Movie Maker were exceptions). As a result, Windows Me was not acknowledged as a unique Operating System along the lines of 95 or 98. Windows Me was widely criticised for serious stability issues, and for lacking real mode DOS support, to the point of being referred to as the "Mistake Edition" or Me meaning "Many Errors". Windows Me was the last operating system to be based on the Windows 9x (monolithic) kernel and MS-DOS. It is also the last 32-bit release of Microsoft Windows which does not include Product Activation.

Windows XP

In 2001, Microsoft introduced Windows XP (code named "Whistler"). The merging of the Windows NT/2000 and Windows 95/98/Me lines was finally achieved with Windows XP. Windows XP uses the Windows NT 5.1 kernel, marking the entrance of the Windows NT core to the consumer market, to replace the aging 16/32-bit branch. The initial release met with considerable criticism, particularly in the area of security, leading to the release of three major Service Packs. Windows XP SP1 was released in September of 2002, SP2 came out in August, 2004 and SP3 came out in April, 2008. Service Pack 2 provided significant improvements and encouraged widespread adoption of XP among both home and business users. Windows XP lasted longer than any other version of Windows, from 2001 to 2007 when Windows Vista was released to consumers. The Windows XP line of operating systems was succeeded by Windows Vista on 30 January 2007.
Windows XP is available in a number of versions:

• Windows XP Home Edition, for home desktops and laptops (notebooks)
  
• Windows XP Home Edition N, as above, but without a default installation of Windows Media Player, as mandated by a European Union ruling
  
• Windows XP Professional, for business and power users
  
• Windows XP Professional N, as above, but without a default installation of Windows Media Player, as mandated by a European Union ruling
  
• Windows XP Media Center Edition (MCE), released in November 2002 for desktops and notebooks with an emphasis on home entertainment
  
• Windows XP Media Center Edition 2003
  
• Windows XP Media Center Edition 2004
  
• Windows XP Media Center Edition 2005, released on 12 October 2004.
  
• Windows XP Tablet PC Edition, for tablet PCs (PCs with touch screens)
  
• Windows XP Tablet PC Edition 2005
  
• Windows XP Embedded, for embedded systems
  
• Windows XP Starter Edition, for new computer users in developing countries
  
• Windows XP Professional x64 Edition, released on 25 April 2005 for home and workstation systems utilizing 64-bit processors based on the x86-64 instruction set developed by AMD as AMD64; Intel calls their version Intel 64
  
• Windows XP 64-bit Edition, is a version for Intel's Itanium line of processors; maintains 32-bit compatibility solely through a software emulator. It is roughly analogous to
• Windows XP Professional in features. It was discontinued in September 2005 when the last vendor of Itanium workstations stopped shipping Itanium systems marketed as "Workstations".
  
• Windows XP 64-bit Edition 2003, based on the Windows NT 5.2 codebase.

Windows Vista

The current client version of Windows, Windows Vista (codenamed Longhorn) was released on 30 November 2006 to business customers, with consumer versions following on 30 January 2007. Windows Vista intended to have enhanced security by introducing a new restricted user mode called User Account Control, replacing the "administrator-by-default" philosophy of Windows XP. Vista also features new graphics features, the Windows Aero GUI, new applications (such as Windows Calendar, Windows DVD Maker and some new games including Chess, Mahjong, and Purble Place), a revised and more secure version of Internet Explorer, a new version of Windows Media Player, and a large number of underlying architectural changes.
Windows Vista ships in several editions:

• Starter (only available in developing countries)
  
• Home Basic
  
• Home Premium
  
• Business
  
• Enterprise (only available to large businesses and enterprises)
  
• Ultimate (combines both Home Premium and Enterprise)
  

All editions (except Starter edition) are currently available in both 32-bit and 64-bit versions. The biggest advantage of the 64-bit version is breaking the 4 gigabyte memory barrier, which 32-bit computers cannot fully access. In the first year after Vista's release, most installations were still 32-bit, due to poor driver support of the 64-bit version.

Windows 7

Windows 7 is the next major release after Windows Vista and is planned for a three-year development timeframe. It was previously known by the code-names Blackcomb and Vienna.
Some features of Windows 7 are faster boot-up, Device Stage, Windows PowerShell, less obtrusive User Account Control, multi-touch, improved window management, homegroup networking, multiple thumbnails for combined taskbar buttons, and better power management for notebooks. Features included with Windows Vista and not in the Windows 7 Release Candidate include the sidebar (although gadgets remain) and several programs that were removed in favor of downloading their Windows Live counterparts.
On February 3rd, 2009, Microsoft announced that Windows 7 would ship in six editions:

• Starter (available worldwide with new PCs only)
  
• Home Basic (only available to emerging markets)
  
• Home Premium
  
• Professional
  
• Enterprise (only available to volume-license business customers only)
  
• Ultimate (available to retail market with limited availability to OEMs)
  

Microsoft will focus on selling Windows 7 Home Premium and Professional. All editions, except the Starter edition, will be available in both 32-bit and 64-bit versions. According to Paul Thurrott, news editor for Windows IT Pro Magazine, Microsoft plans to ship Windows 7 in 2009.

ANALOG COMPUTERS

Analog Computers and Digital computers are the two kinds of computers, the combination of which is responsible for the invention of the modern Hybrid computers. The analog systems carry out arithmetic and logical operations by manipulating and processing data which you input such as the weight, temperature, voltage, power density, etc. But unlike the digital computer that changes all inputs to binary digits of “1” and “0”, the analog computer does not change inputted data to any such sign language.

The analog computer has become obsolete type of computer these days. It is different from a digital computer as it can perform numerous mathematical operations simultaneously. The digital computers, however could not operate the more complex operations. The Analog System is also unique in terms of operation as it utilizes continuous variables for the purpose of mathematical computation. It utilizes mechanical, hydraulic, or electrical energy or operation.
Analog computers are based on principles completely different from digital computers. Problem variables are represented by electrical voltages which can vary continuously within a certain range, usually -10 to +10 volts for a transistor-based machine. Electronic circuit modules allow the variables to be added, integrated (with respect to time) and multiplied by a constant. This makes it is possible to solve a system of ordinary linear differential equations by properly combining a number of adders, integrators, amplifiers and potentiometers using flexible chords and a patch panel (see the examples).

Analog computer programming

The figure shows the set-up for the solution of a very simple second-order linear differential equation, representing the dynamics of a body moving (in one dimension) under the influence of gravity. Before the computation can be started, initial conditions (IC) must be specified. This is accomplished by charging the capacitors in both integrators to the voltages representing the zero-time velocity and position, respectively. On the patch panel a special IC input is provided for every integrator. By simply turning a console switch controlling the value of the integrating capacitors, the problem's time scale can be scaled up or down, making it suitable for plotting on a pen recorder, or for viewing on an oscilloscope. In the latter case the solution can be repeated quickly completely automatically.

The next, more complicated example is a program for solving a pair of coupled second-order linear differential equations. Finally I'll show an example of a sequential optimization program , running on a hybrid configuration (a combination of an analog and a digital computer). Note that the digital part is used only for storing intermediate results.

References

MacKay and Fisher: Analogue Computing at Ultra-high Speed. Chapman & Hall (London) 1962
Korn and Korn: Electronic Analog and Hybrid Computers. MacGraw-Hill (New-York) 1964
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Large machines like the EAI 680 also support non-linear operations: square-rooting, arbitrary (piecewise linear) function generation, multiplication of two variables, and comparing the values of two variables. The last mentioned operation results in a boolean quantity which, perhaps combined with other boolean results (using the machine's patchable logic circuitry) can be used to change the 'program' dynamically. For instance, the simulation of a bouncing ball requires the solution of one differential equation when the ball is in free fall, while another equation (describing the forces occurring during elastic deformation) is applicable when the ball is in ground contact. The results of the computation can be shown graphically graphically, in real time, on an oscilloscope or plotter, or be digitized for being stored or further processed by a digital computer in a hybrid system. Also the results can be used directly for the control of some physical process.
The analog computer which is a complex machine is an integration of various mechanical parts which has pipes, valves, levers, gears and several key parts which can be named as follows :-

• Fixed function generators
  







• Operational amplifiers
  







• Potentiometers
  







• Integrators
  







• Advantages and Disadvantages of Analog Computers
  

The advantage of an analog computer is that it can simultaneously find solutions to several mathematical problems and that too while being precise unlike the digital computer. But it is not free of drawbacks. Unlike the digital computer it lacks speed of calculation. There are other functional problems which mar the efficiency of analog systems. Of these, the problems of non-linearities, temperature co-efficient, parasitic effects and noise floor are the main problems so to say. The core mathematical operations used in an electric analog computer are :-

• Summation
  







• inversion
  







• exponentiation
  







• logarithm
  







• integration with respect to time
  







• differentiation with respect to time
  







• multiplication and division
  

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Desktop Computers

Desktop computers are the most widely used Personal Computers which still claim a fair share of 46% of the total world market. In spite of the fact that PCs are now dwarfed to Laptops and Palmtops, Desktop machines rule most homes and business institutions because of their durability and cheapness. Desktop Personal Computers are found almost every where – almost in all middle class Indian homes, cyber cafes, shopping malls, business institutions, offices, etc.
The History of Desktop computers being produced at amass scale dates back to around the late 70s of the 20th century. When you come across a typical desktop computer, note that the PC that includes the following parts is visible to you:

• A Visual Display Unit (VDU)
  



• A Keyboard
  



• A Central Processing Unit (CPU)
  



• A Mouse
  

There can be in addition to these a pair of Sound box, Web Cam, Joystick, etc.
Besides the mechanical components of a Desktop system, or the hardware system of the desktop computer comprises:

• Mother Board (System Board) – The mother board, a board concerning printed circuit, is the most important component of the Desktop computer as it contains and connects all the important parts of the hardware. It basically consists of the keyboard connector, RAM, AGP PCI and ISA slots, CPU, battery, expansion board and L2 Cache.
  



• Processor – This can be called the chief brain of the computer.
  



• Hard Disk drive – It is that part of the memory which the regular user can utilize for the purpose of working and storing data.
  



• Optical Disc Drive – This is the component for playing CD s and DVD s.
  



• Floppy Disc drive – The part that helps in the running of a floppy.
  



• Random Access Memory – The permanent memory that cannot be erased by the user
  



• Modem – This is the component used to connect to BBS, dial up network and of course the Internet.
  Computer Power Supply Unit – This is the unit that is responsible for supplying the system with electrical power.
  Various cards and Coolers.
  Today Desktop machines are manufactured by a wide range of companies, though integrated Desktops Personal Computers are also popular. HP computer, Toshiba , HCL, ACER to name a few a few of them.

DIGITAL COMPUTER

Digital Computers are that kind of computing machines which work on the principle of binary mathematics. Digital computing machines when clubbed with Analog computers produce Hybrid computers. The digital systems work on the principle of binary mathematics. In binary mathematics all calculations are represented through “0” and “1”.


You have often heard about the word “Byte”, “Mega Byte”, “Kilo Byte”. But what is a Byte? A single Byte is a group of 8 numbers or bits represented through a code series comprising of “0” and “1” .The combination of the digital signal can solve a number of mathematical operations. It is interesting to note that the fundamentals of mathematics applied are addition, subtraction, multiplication and division. But the chief problem is that though it can solve mathematical problems at a tremendous speed, it cannot perform bulk operations simultaneously. For this purpose, digital systems by themselves cannot give very precise results. Hence, for greater efficiency, the Digital systems do not find much application.


Data Processing In Digital Computers Digital computers function with the help of logic circuits. A reliable oscillator helps in the proper synchronization of various logic circuits that are responsible for processing data in the digital computers. In better quality computers, the oscillation rate might even be a billion cycles per second. Operating at such high speed, it can process more than billions of logic and arithmetic problems.


A digital computer with the help of binary system cannot only perform mathematical problems but also combine the bytes to produce desired graphics, sounds, images and other such commands.

Embedded Computers

Embedded computers are not just computer systems where you can input new programs, the embedded devices are preprogrammed. All you can do is make the most of the services that the embedded computer systems are capable of providing. Ever thought of how your digital camera or cell phone, or washing machine works? Sure they work with the support of electricity or may be they are battery powered but the functions that they execute is entirely because of the embedded systems.
Important features of embedded computers constitute:
The functions of the Embedded systems are not generic but rather specific.
In most cases Embedded computers are built in parts. Usually they constitute a single board or a chip placed inside the concerned machine that it must operate.
The software running the embedded computer systems is not stored in the disc drive but rather in the ROM. The software language used for writing the program is called FIRMWIRE.
Embedded Computers are capable of communicating with the world outside.
They do it with the help of peripherals. These peripherals comprise:

1.Universal Serial Bus (USB)

2.Synchronous Serial Communication Interface:
I2C, JTAG, SPI, SSC and ESSI

3.Discrete IO: aka General Purpose Input/Output (GPIO)

4.Networks: Controller Area Network, Lon Works, etc.

5.Serial Communication Interfaces (SCI): RS-232, RS-422, RS- 485 etc.,

6.Timers: PLL(s), Capture/Compare and Time Processing Units

LAPTOP

Laptops or Notebook computers are a type of personal computers which are portable devices. The special feature of laptop computers is that it is far lighter than a Desktop PC. Being a wireless system, you can use it even when there is a power cut or you are away from home where electricity is not available.
Laptops or Notebook Computers are different from a desktop computer not only in terms of size and portability but the following factors count for the basic difference:

• In laptops, the mouse, keyboard and sound box is integrated with the main system itself.
  



• A notebook computer is not powered by electricity but by a battery.
  



• Nowadays networking features like Intel Centrino mobile Technology is installed within the laptop computers itself.
  



• In most laptops with the exception of a few like Alienware, the internal parts cannot be updated once you have bought the Laptop.
  



• And to say the least it is far more fragile than a Desktop PC.
  While buying a Laptop computer you need to consider the quality of the portable computer. What accounts for the portability, are the following factors. So make sure to check out that the basic components of the system, that is to say, the Processor, Memory, Mass Storage and Removal components and the peripheral accessories should be designed in such a way that it is
  As light and small as possible;
  Should be powered by a proper battery which must generate minimum heat;
  Should be accessible by a floppy or a CD.