Personal Computers

Personal Computers are desktop computers designed for an individual's use. They run programs designed to help individuals accomplish their work more productively.

Servers

Servers are not designed to be used directly. They make programs and data available for people hooked up to a computer network, a collection of computers connected together so that they can exchange data.

Minicomputers

Minicomputers are multi-user systems that can handle the computing needs of a smaller corporation or organization. Many people use them simultaneously by means of remote terminals or personal computers.

Mainframe computers

Mainframes are huge, multi-user systems designed to handle gigantic processing jobs in large corporations or government agencies.

Categories of Computers

Personal Computers

Personal Computers are desktop computers designed for an individual's use. They run programs designed to help individuals accomplish their work more productively.

Servers

Servers are not designed to be used directly. They make programs and data available for people hooked up to a computer network, a collection of computers connected together so that they can exchange data.

Minicomputers

Minicomputers are multi-user systems that can handle the computing needs of a smaller corporation or organization. Many people use them simultaneously by means of remote terminals or personal computers.

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Mainframe computers

Mainframes are huge, multi-user systems designed to handle gigantic processing jobs in large corporations or government agencies.

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Supercomputers

Supercomputers are ultra fast computers designed to process hugh amounts of scientific data then display the underlying patterns that have been discovered.

History of Computer

Nearly 5,000 years ago the abacus emerged in Asia Minor. The abacus may be considered the first computer. This device allowed its users to make computations using a system of sliding beads arranged on a rack. Early shopkeepers used the abacus to keep up with transactions. The use of pencil and paper spread, the abacus lost its importance. Nearly twelve centuries past before the next important advance in computing devices emerged.

In 1642, Blaise Pascal, the 18-year-old son of a French tax collector, invented what he called a numerical wheel calculator to help his father with his duties. The Pascaline, a brass rectangular box, used eight movable dials to add sums up to eight figures long. Pascal's device used a base of ten to achieve this. The disadvantage to the Pascaline, of course, was its limitation to addition. In 1694, Gottfried Wilhem von Leibniza a German mathematician and philosopher improved the Pascaline by creating a machine that could also multiply. Like its predecessor, Leibniz's mechanical multiplier worked by a system of gears and dials.

It wasn't until 1820, however, that mechanical calculators gained widespread use. A Frenchman, Charles Xavier Thomas de Colmar, invented a machine that could perform the four basic mathematic functions. The arithometer, presented a more systematic approach to computing because it could add, subtract, multiply and divide. With its enhanced versatility, the arithometer was widely used up until World War I.

The real beginnings of computers began with an English mathematics professor, Charles Babbage. Babbage's steam-powered Engine, outlined the basic elements of a modern general purpose computer and was a breakthrough concept. The Analytical Engine consisted of over 50,000 components. The basic design of included input devices in the form of perforated cards containing operating instructions and a "store" for memory of 1,000 numbers of up to 50 decimal digits long.

In 1889, an American inventor, Herman Hollerith, created a machine that used cards to store data information which was fed into a machine and compiled the results mechanically. Each punch on a card represented one number, and combinations of two punches represented one letter. As many as 80 variables could be stored on a single card. Hollerith brought his punch card reader into the business world, founding Tabulating Machine Company in 1896, later to become International Business Machines (IBM) in 1924 after a series of mergers. Other companies also manufactured punch readers for business use. Both business and government used punch cards for data processing until the 1960's.

When World War II began, the governments sought to develop computers to accomplishment their potential strategic importance. This increased funding for computer development projects and hastened technical progress. In 1941, a German engineer Konrad Zuse had developed a computer to design airplanes and missiles. The Allied forces, however, made greater strides in developing powerful computers. American efforts produced a broader achievement. In 1933, Howard H. Aiken, a Harvard engineer working with IBM, succeeded in producing an all-electronic calculator. The purpose of the computer was to create ballistic charts for the U.S. Navy. It was about half as long as a football field and contained about 500 miles of wiring. It used electromagnetic signals to move mechanical parts. The machine was slow taking 3-5 seconds per calculation and inflexible in that sequences of calculations could not change; but it could perform basic arithmetic as well as more complex equations.

Another computer development spurred by the war was the Electronic Numerical Integrator and Computer (ENIAC). It consisted of 18,000 vacuum tubes, 70,000 resistors and 5 million soldered joints, the computer was such a massive piece of machinery that it consumed 160 kilowatts of electrical power. ENIAC was developed by John Presper Eckert and John W. Mauchl. ENIAC was a general-purpose computer.

In 1945, Von Neumann designed the Electronic Discrete Variable Automatic Computer (EDVAC) with a memory to hold both a stored program as well as data. This "stored memory" technique as well as the "conditional control transfer," that allowed the computer to be stopped at any point and then resumed, allowed for greater versatility in computer programming. The key element to the von Neumann architecture was the central processing unit, which allowed all computer functions to be coordinated through a single source. In 1951, the UNIVAC I (Universal Automatic Computer), built by Remington Rand, became one of the first commercially available computers to take advantage of these advances. The first computers were characterized by the fact that operating instructions were made-to-order for the specific task for which the computer was to be used. Each computer had a different binary-coded program called a machine language that told it how to operate. This made the computer difficult to program and limited its versatility and speed. Other unique features of first computers were the use of vacuum tubes and magnetic drums for data storage.

The invention of the transistor greatly changed the computer's development in 1948. The transistor replaced the large, cumbersome vacuum tubes. The transistor was at work in the computer by 1956. Throughout the early 1960's, there were a number of commercially successful computers used in business, universities, and government from companies such as Burroughs, Honeywell, IBM, and others. These computers also contained transistors in place of vacuum tubes. They also contained all the components we associate with the modern day computer: printers, disk storage, memory, tape storage, operating systems, and stored programs.

By 1965, most large business routinely processed financial information using computers. It was the stored program and programming language that gave computers the flexibility to finally be cost effective and productive for business use. Though transistors were clearly an improvement over the vacuum tube, they still generated a great deal of heat, which damaged the computer's sensitive internal parts. Jack Kilby, an engineer with Texas Instruments, developed the integrated circuit in 1958. The IC combined three electronic components onto a small silicon disc, which was made from quartz. Scientists later managed to fit even more components on a single chip, called a semiconductor.

By the 1980's, very large scale integration squeezed hundreds of thousands of components onto a chip. Ultra-large scale integration increased that number into the millions. The ability to fit so much onto an area about half the size of a dime helped diminish the size and price of computers. It also increased their power, efficiency and reliability. By the mid-1970's, computer manufacturers sought to bring computers to general consumers. These minicomputers came complete with user-friendly software packages that offered even non-technical users an arrangement of applications, most popularly word processing and spreadsheet programs.

In 1981, IBM introduced its personal computer (PC) for use in the home, office and schools. The 1980's saw an expansion in computer use in all three arenas as clones of the IBM PC made the personal computer even more affordable. The number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used. As computers became more widespread in the workplace, new ways to harness their potential developed. As smaller computers became more powerful, they could be linked together, or networked, to share memory space, software, information and communicate with each other. Computers continue to grow smaller and more powerful.

Monitor the temperature of CPU

Core Temp is a software that helps you keep checking the temperature of CPU.

The unique point of Core Temp is that it can have separate monitor to check the temperature of separate CPU. As such, if you are using Duo Core CPU, you will then be provided with two meters of temperature.

It can also enable you to know the real-time changes of temperature too. Of course, graphical representation to users is also available.

Toshiba Laptop - Satellite L300-ST2501

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Built around Intel® Centrino® Processor Technology and ample memory, these laptops supercharge most anything you do, from multitasking, balancing the family budget or studying for finals. And when you're ready to move out, integrated Wi-Fi lets you stay connected or work the Web at any wireless hotspots.

Base laptop includes:

- Genuine Windows Vista® Home Basic 32-Bit
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What is an Operating System

The operating system is the core software component of your computer. It performs many functions and is, in very basic terms, an interface between your computer and the outside world. In the section about hardware, a computer is described as consisting of several component parts including your monitor, keyboard, mouse, and other parts. The operating system provides an interface to these parts using what is referred to as "drivers". This is why sometimes when you install a new printer or other piece of hardware, your system will ask you to install more software called a driver.

What does a driver do?

A driver is a specially written program which understands the operation of the device it interfaces to, such as a printer, video card, sound card or CD ROM drive. It translates commands from the operating system or user into commands understood by the the component computer part it interfaces with. It also translates responses from the component computer part back to responses that can be understood by the operating system, application program, or user. The below diagram gives a graphical depiction of the interfaces between the operating system and the computer component.

Causes of a slow PC

There are many possible causes of a slow PC. Because your computer is constantly working with files - moving, copying and deleting from place to place - it will eventually get cluttered with leftover files, some of which are not needed and just take up valuable disk space. You only have a certain amount of disk space available on your hard disk, and as it fills up the computer can begin to struggle to find room to perform its tasks.

If your PC crashes or freezes up, it may be a symptom of a slow or cluttered PC.The brain of your computer is the Processor, and it may be that your processor is too slow to run today's demanding software. The processor can also struggle if you have multiple programs running at once - for example, if you have Word open to compose a letter while downloading a file from the Internet and also playing a song through your media player.

RAM is the temporary memory the computer uses to do its calculations. If you do not have enough RAM, your programs will run slowly.

Other components of your PC can contribute to poor performance, particularly your Graphics Card when it comes to running media and games software. Some hardware needs special programs called Drivers and these need to be kept up to date.

You may also have programs running in the background using up memory that you are unaware of, and in some cases, the problem may be a malicious program such as a virus or spyware.

Tips To Make Your PC Run Faster

Remove Malicious Programs

It is important that you use up-to-date security software to detect and remove malicious programs. Virus programs can slow down your PC and cause unwanted behaviour, even damage to your data.

Spyware tracks your movements on the Web for advertising purposes, but can affect your PC's performance as well. Use anti-spyware programs to remove it.


Clear Out Junk Files

Any time you visit a web site, your computer needs to download the page along with any pictures displayed on it. To prevent your computer having to download the same files again each time you visit the same web site, your web browser will keep a "cache" of stored files it will retrieve if the site hasn't changed since your last visit. Although this means web pages appear faster, over time your cache can eat up a lot of disk space and slow your PC down.

Whenever you delete a file, it is moved to the Recycle Bin first, to give you the chance to change your mind. But the Recycle Bin uses disk space too, so if you leave lots of files in there you are wasting precious space.

Computer Mouse

The Mouse is the device you will use for most of your interactions with your PC. It is primarily used to move the pointer arrow around the screen and to select and activate options.

The mouse buttons are used to interact with whatever is on the screen where the pointer is located. The left mouse button is the one you will use most often. Clicking this tells the PC to select an item and is called 'left-clicking'. To activate an item and use it, you will often need to click the button twice or 'double-click'.

If you click and hold the left button and move the mouse, this has the effect of 'dragging' a selected object about the screen until you release the button.

Left-clicking on text in a document will place a flashing cursor at that point, which allows you to begin typing there.

The right mouse button is usually used to bring up a small menu window that gives options specific to the selected object. To use a particular option you just left-click it.
Common right-click menu options for an object include: Open (activate, same as if you double-click), Cut (remove to be placed elsewhere), Copy (make a copy of this object) , Create Shortcut (create a shortcut link elsewhere to give quick access to this object), Delete (remove permanently), Rename (give a new name), and Properties (find out information).

You may have a third smaller button in the center of your mouse that can be rolled forwards and backwards. This mouse-wheel can be used to move up and down through documents.

Windows Operating System

The operating system that runs all your programs and allows you to easily interact with your PC is called Windows for a good reason. It allows you to work with several different items and programs at once, all in their own 'window'. A window is like a smaller screen contained within a box on your main screen.

When you are working with a window it is brought to the 'front' of the screen, overlapping the Desktop and any other items behind it, so that you can focus on whatever is in the window.

In this way, you can have several windows open at the same time containing different programs that can be opened, closed, and re-arranged across the screen. This means you can do multiple tasks at the same time, such as running a programme while writing an e-mail for example.

What are the bumps at the end of computer cables?

In a typical computer system found in a home or office, you normally see these "bumps" on the mouse, keyboard and monitor cables. You can also find them on power supply wires when a device (like a printer or scanner) uses an external transformer.

These "bumps" are called ferrite beads or sometimes ferrite chokes. Their goal in life is to reduce EMI (electromagnetic interference) and RFI (radio-frequency interference). You can see these beads in the photo on to your right.

A ferrite bead is simply a hollow bead or cylinder made of ferrite, which is a semi-magnetic substance made from iron oxide (rust) alloyed with other metals. It slips over the cable when the cable is made, or it can be snapped around the cable in two pieces after the cable is made. The bead is encased in plastic -- if you cut the plastic, all that you would find inside is a black metal cylinder.

Computers are fairly noisy devices. The motherboard inside the computer's case has an oscillator that is running at anywhere from 300 MHz to 1,000 MHz. The keyboard has its own processor and oscillator as well. The video card has its own oscillators to drive the monitor. All of these oscillators have the potential to broadcast radio signals at their given frequencies. Most of this interference can be eliminated by the cases around the motherboard and keyboard.

Another source of noise is the cables connecting the devices. These cables act as nice, long antennae for the signals they carry. They broadcast the signals quite efficiently. The signals they broadcast can interfere with radios and TVs. The cables can also receive signals and transmit them into the case, where they cause problems. A ferrite bead has the property of eliminating the broadcast signals. Essentially, it "chokes" the RFI transmission at that point on the cable -- this is why you find the beads at the ends of the cables. Instead of traveling down the cable and transmitting, the RFI signals turn into heat in the bead.

How do optical mice work?

It appears that the venerable wheeled mouse is in danger of extinction. The now-preferred device for pointing and clicking is the optical mouse.

Developed by Agilent Technologies and introduced to the world in late 1999, the optical mouse actually uses a tiny camera to take 1,500 pictures every second. Able to work on almost any surface, the mouse has a small, red light-emitting diode (LED) that bounces light off that surface onto a complimentary metal-oxide semiconductor (CMOS) sensor. The CMOS sensor sends each image to a digital signal processor (DSP) for analysis. The DSP, operating at 18 MIPS (million instructions per second), is able to detect patterns in the images and see how those patterns have moved since the previous image. Based on the change in patterns over a sequence of images, the DSP determines how far the mouse has moved and sends the corresponding coordinates to the computer. The computer moves the cursor on the screen based on the coordinates received from the mouse. This happens hundreds of times each second, making the cursor appear to move very smoothly.

Optical mice have several benefits over wheeled mice:

· No moving parts means less wear and a lower chance of failure.
· There's no way for dirt to get inside the mouse and interfere with the tracking sensors.
· Increased tracking resolution means smoother response.
· They don't require a special surface, such as a mouse pad.

In the photo on top, you can see the LED on the bottom of the mouse.

Keyboard Basics

When you look at all the extras and options that are available for new computer keyboards, it can be hard to believe that their original design came from mechanical typewriters that didn't even use electricity. Now, you can buy ergonomic keyboards that bear little resemblance to flat, rectangular models with ordinary square keys. Some flashier models light up, roll up or fold up, and others offer options for programming your own commands and shortcuts. They use switches and circuits to translate a person's keystrokes into a signal a computer can understand.

A keyboard's primary function is to act as an input device. Using a keyboard, a person can type a document, use keystroke shortcuts, access menus, play games and perform a variety of other tasks. Keyboards can have different keys depending on the manufacturer, the operating system they're designed for, and whether they are attached to a desktop computer or part of a laptop. But for the most part, these keys, also called keycaps, are the same size and shape from keyboard to keyboard. They're also placed at a similar distance from one another in a similar pattern, no matter what language or alphabet the keys represent.

Most keyboards have between 80 and 110 keys, including:

- Typing keys
- A numeric keypad
- Function keys
- Control keys

The typing keys include the letters of the alphabet, generally laid out in the same pattern used for typewriters. According to legend, this layout, known as QWERTY for its first six letters, helped keep mechanical typewriters' metal arms from colliding and jamming as people typed. Some people question this story – whether it’s true or not, the QWERTY pattern had long been a standard by the time computer keyboards came around. typing keys include the letters of the alphabet, generally laid out in the same pattern used for typewriters. This layout, known as QWERTY for its first six letters, helped keep mechanical typewriters' metal arms from colliding and jamming as people typed. Because this pattern had been long established as a standard, manufacturers developed keyboards for computers using the same layout, even though jamming was no longer an issue.

How do CD-R discs work?

The basic idea behind data storage on a normal CD is simple. The surface of the CD contains one long spiral track of data. Along the track, there are flat reflective areas and non-reflective bumps. A flat reflective area represents a binary 1, while a non-reflective bump represents a binary 0. The CD drive shines a laser at the surface of the CD and can detect the reflective areas and the bumps by the amount of laser light they reflect. The drive converts the reflections into 1s and 0s to read digital data from the disc.

Normal CDs can not be modified -- they are read-only devices. A CD-R disc needs to allow the drive to write data onto the disc. For a CD-R disk to work, there must be a way for a laser to create a non-reflective area on the disc. A CD-R disc therefore has an extra layer that the laser can modify. This extra layer is a greenish dye. In a normal CD, you have a plastic substrate covered with a reflective aluminum or gold layer. In a CD-R, you have a plastic substrate, a dye layer and a reflective gold layer. On a new CD-R disc, the entire surface of the disc is reflective -- the laser can shine through the dye and reflect off the gold layer.

When you write data to a CD-R, the writing laser (which is much more powerful than the reading laser) heats up the dye layer and changes its transparency. The change in the dye creates the equivalent of a non-reflective bump. This is a permanent change, and both CD and CD-R drives can read the modified dye as a bump later on. It turns out that the dye is fairly sensitive to light -- it has to be in order for a laser to modify it quickly. Therefore, you want to avoid exposing CD-R discs to sunlight.

Personal Digital Assistant (PDA)

The main purpose of a personal digital assistant (PDA) is to act as an electronic organizer or day planner that is portable, easy to use and capable of sharing information with your PC. It's supposed to be an extension of the PC, not a replacement.

PDAs, also called handhelds or palmtops, have definitely evolved over the years. Not only can they manage your personal information, such as contacts, appointments, and to-do lists, today's devices can also connect to the Internet, act as global positioning system (GPS) devices, and run multimedia software. What's more, manufacturers have combined PDAs with cell phones, multimedia players and other electronic gadgetry.

What if I am out of USB ports in my PC?

Just about every peripheral made now comes in a USB version. Here's a list of some of the USB devices that you can buy today:

Printers, Scanners, Mice, Joysticks, Digital cameras, Webcams, Modems, Speakers, Telephones, Video phones, Storage devices like Zip drives, Network connections, etc.

Computers that you buy may come with only one or two USB sockets. With so many USB devices on the market today, you easily run out of USB sockets very quickly.

For example, on the computer that I am typing on right now, I have a USB printer, a USB scanner, a USB Webcam and a USB network connection. My computer has only one USB connector on it, so the obvious question is, "How do you hook up all the devices?"

The easy solution to the problem is to buy an inexpensive USB hub. The USB standard supports up to 127 devices.

A hub typically has four new ports, but may have many more. You plug the hub into your computer, and then plug your devices (or other hubs) into the hub. By chaining hubs together, you can build up dozens of available USB ports on a single computer.

What does Alt+F4 do?

This is one of those jokes people play on each other -- it's in the same category with squirting flowers and exploding cigars. This joke works on machines running the Windows operating system because Windows happens to define certain keystrokes that work the same way in all applications. Just about everyone knows that Alt+Ctrl+Del interrupts the operating system, but most people don't know that Alt+F4 closes the current window. So if you had pressed Alt+F4 while playing a game, the game window would have closed.

It turns out there are several other handy keystrokes like that built into Windows. For example, Ctrl+Esc will pop up the Start menu, Alt+Esc will bring the next window to the foreground, and Alt+Tab or Alt+Shift+Tab will let you cycle through all available windows and jump to the one you select.

On keyboards that have the little "Windows" key (let's call it WK here) down near the space bar, you probably know that you can press that key to open the Start menu.

You can also use that key with other keys like you use the shift key. For example:

WK+e - starts the Windows Explorer
WK+f - starts the Find in Files dialog
WK+Ctrl+f - starts the Find a Computer on the Network dialog
WK+M - minimizes all the windows to clear the desktop
WK+Shift+M - restores all the minimized windows
WK+r - starts the Run dialog
WK+F1 - starts Windows Help
WK+Pause - starts System Properties

Hard Disk Basics

Hard disks were invented in the 1950s. They started as large disks up to 20 inches in diameter holding just a few megabytes. They were originally called "fixed disks" or "Winchesters" (a code name used for a popular IBM product). They later became known as "hard disks" to distinguish them from "floppy disks." Hard disks have a hard platter that holds the magnetic medium, as opposed to the flexible plastic film found in tapes and floppies.

At the simplest level, a hard disk is not that different from a cassette tape. Both hard disks and cassette tapes use the same magnetic recording techniques. Hard disks and cassette tapes also share the major benefits of magnetic storage -- the magnetic medium can be easily erased and rewritten, and it will "remember" the magnetic flux patterns stored onto the medium for many years.

Nearly every desktop computer and server in use today contains one or more hard-disk drives. Every mainframe and supercomputer is normally connected to hundreds of them. You can even find VCR-type devices and camcorders that use hard disks instead of tape. These billions of hard disks do one thing well -- they store changing digital information in a relatively permanent form. They give computers the ability to remember things when the power goes out.