Saturday, 11 August 2012

Computer Components

Computer Case

A computer case (also known as a computer chassis, cabinet, box, tower, enclosure, housing, system unit or simply case) is the enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse). A computer case is sometimes incorrectly referred to metonymously as a CPU referring to a component housed within the case. CPU was a common term in the earlier days of home computers, when peripherals other than the motherboard were usually housed in their own separate cases.

Power supply

A power supply unit (PSU) converts alternating current (AC) electric power to low-voltage DC power for the internal components of the computer. Some power supplies have a switch to change between 230 V and 115 V. Other models have automatic sensors that switch input voltage automatically, or are able to accept any voltage between those limits. Power supply units used in computers are nearly always switch mode power supplies (SMPS). The SMPS provides regulated direct current power at the several voltages required by the motherboard and accessories such as disk drives and cooling fans.


The motherboard is the main component inside the case. It is a large rectangular board with integrated circuitry that connects the other parts of the computer including the CPU, theRAM, the disk drives (CDDVDhard disk, or any others) as well as any peripherals connected via the ports or the expansion slots.
Components directly attached to the motherboard include:
  • The CPU (Central Processing Unit) performs most of the calculations which enable a computer to function, and is sometimes referred to as the "brain" of the computer. It is usually cooled by a heat sink and fan. Most newer CPUs include an on-die Graphics Processing Unit (GPU).
  • The Chipset, which includes the north bridge, mediates communication between the CPU and the other components of the system, including main memory.
  • The Random-Access Memory (RAM) stores the code and data that are being actively accessed by the CPU.
  • The Read-Only Memory (ROM) stores the BIOS that runs when the computer is powered on or otherwise begins execution, a process known as Bootstrapping, or "booting" or "booting up". The BIOS (Basic Input Output System) includes boot firmware and power management firmware. Newer motherboards use Unified Extensible Firmware Interface (UEFI) instead of BIOS.
  • Buses connect the CPU to various internal components and to expansion cards for graphics and sound.
    • Current
      • PCI Express: for expansion cards such as graphics, sound, network interfaces, TV tuners, etc.
      • PCI: for other expansion cards.
      • SATA: for disk drives.
    • Obsolete
  • Ports for external peripherals. These ports may be controlled directly by the south bridge I/O controller or provided by expansion cards attached to the motherboard.

Expansion Cards

The expansion card (also expansion board, adapter card or accessory card) in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.
An example of an expansion card is a sound card that enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers have hardware support for sound integrated in the motherboard chipset but some users prefer to install a separate sound card as an upgrade. Most sound cards, either built-in or added, have surround sound capabilities and 3-D sound effects.

Secondary Storage Devices

Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is a core function and fundamental component of computers.

[edit]Fixed Media Devices

  • Hard disk drives: a hard disk drive (HDD; also hard drive, hard disk, or disk drive)[2] is a device for storing and retrieving digital information, primarily computer data. It consists of one or more rigid (hence "hard") rapidly rotating discs (often referred to as platters), coated with magnetic material and with magnetic heads arranged to write data to the surfaces and read it from them.
  • Solid-state drives: a solid-state drive (SSD), sometimes called a solid-state disk or electronic disk, is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block I/O hard disk drive. SSDs are distinguished from traditional magnetic disks such as hard disk drives (HDDs) or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads.
  • RAID array controller - a device to manage several internal or external hard disks and optionally some peripherals in order to achieve performance or reliability improvement in what is called a RAID array.

[edit]Removable Media Devices

  • Optical Disc Drives for reading from and writing to various kinds of optical media, including Compact Discs such as CD-ROMs,DVDsDVD-RAMs and Blu-ray DiscsOptical discs are the most common way of transferring digital video, and are popular for data storage as well.
  • Floppy disk drives for reading and writing to floppy disks, an outdated storage media consisting of a thin disk of a flexible magnetic storage medium. These were once standard on most computers but are no longer in common use. Floppies are used today mainly for loading device drivers not included with an operating system release (for example, RAID drivers).
  • Zip drives, an outdated medium-capacity removable disk storage system, for reading from and writing to Zip disks, was first introduced by Iomega in 1994.
  • USB flash drive plug into a USB port and do not require a separate drive. USB flash drive is a typically small, lightweight, removable, and rewritable flash memory data storage device integrated with a USB interface. Capacities vary, from hundreds of megabytes (in the same range as CDs) to tens of gigabytes (surpassing Blu-ray discs but also costing significantly more).
  • Memory card readers for reading from and writing to Memory cards, a flash memory data storage device used to store digital information. Memory cards are typically used on mobile devices. They are thinner, smaller and lighter than USB flash drives. Common types of memory cards are SD and MS.
  • Tape drives read and write data on a magnetic tape, and are used for long term storage and backups.

Input and output peripherals


  • Text input devices
    • Keyboard - a device to input text and characters by depressing buttons (referred to as keys or buttons).
  • Pointing devices
    • Mouse - a pointing device that detects two dimensional motion relative to its supporting surface.
      • Optical Mouse - uses light (laser technology) to determine mouse motion.
    • Trackball - a pointing device consisting of an exposed protruding ball housed in a socket that detects rotation about two axes.
    • Touchscreen - senses the user pressing directly on the monitor.
  • Gaming devices
    • Joystick - a hand-operated pivoted stick whose position is transmitted to the computer.
    • Game pad - a hand held game controller that relies on the digits (especially thumbs) to provide input.
    • Game controller - a specific type of controller specialized for certain gaming purposes.
  • ImageVideo input devices
    • Image scanner - a device that provides input by analyzing images, printed text, handwriting, or an object.
    • Web cam - a video camera used to provide visual input that can be easily transferred over the internet.
  • Audio input devices
    • Microphone - an acoustic sensor that provides input by converting sound into electrical signals.



Computer Of Classification

Computers are available in different shapes, sizes and weights, due to these different shapes and sizes they perform different sorts of jobs from one another.
They can also be classified in different ways. All the computers are designed by the qualified computer architectures that design these machines as their requirements.
A computer that is used in a home differs in size and shape from the computer being used in a hospital. Computers act as a server in large buildings, while the computer also differs in size and shape performing its job as a weather forecaster.
A student carrying a laptop with him to his college is different in shape and size from all the computers mentioned above.
Here we are going to introduce different classifications of computers one by one. We will discuss what are in classifications and what job they perform.

Super computer

The biggest in size, the most expensive in price than any other is classified and known as super computer. It can process trillions of instructions in seconds. This computer is not used as a PC in a home neither by a student in a college.
Governments specially use this type of computer for their different calculations and heavy jobs. Different industries also use this huge computer for designing their products.
In most of the Hollywood's movies it is used for animation purposes. This kind of computer is also helpful for forecasting weather reports worldwide.


Another giant in computers after the super computer is Mainframe, which can also process millions of instruction per second and capable of accessing billions of data.
This computer is commonly used in big hospitals, air line reservations companies, and many other huge companies prefer mainframe because of its capability of retrieving data on a huge basis.
This is normally to expensive and out of reach from a salary-based person who wants a computer for his home.
This kind of computer can cost up to thousands of dollars.


This computer is next in he line but less offers less than mainframe in work and performance. These are the computers, which are mostly preferred by the small type of business personals, colleges, etc.

Personal computers

Almost all the computer users are familiar with the personal computers. They normally know what the personal computer is and what are its functions.
This is the computer mostly preferred by the home users. These computers are lesser in cost than the computers given above and also, small in size; they are also called PCs in short for Personal computers.
This computer is small in size and you can easily arrange it to fit in your single bedroom with its all accommodation. Today this is thought to be the most popular computer in all.

Notebook computers

Having a small size and low weight the notebook is easy to carry to anywhere. A student can take it with him/her to his/her school in his/her bag with his/her book.
This is easy to carry around and preferred by students and business people to meet their assignments and other necessary tasks.
The approach of this computer is also the same as the Personal computer. It can store the same amount of data and having a memory of the same size as that of a personal computer. One can say that it is the replacement of personal desktop computer.

Sunday, 5 August 2012

Computer History and Generations

In the beginning ...
        A generation refers to the state of improvement in the development of a product.  This term is also used in the different advancements of computer technology.  With each new generation, the circuitry has gotten smaller and more advanced than the previous generation before it.  As a result of the miniaturization, speed, power, and memory of computers has proportionally increased.  New discoveries are constantly being developed that affect the way we live, work and play.

The First Generation:  1946-1958 (The Vacuum Tube Years)

        The first generation computers were huge, slow, expensive, and often undependable.  In 1946two Americans, Presper Eckert, and John Mauchly built the ENIAC electronic computer which used vacuum tubes instead of the mechanical switches of the Mark I.  The ENIAC used thousands of vacuum tubes, which took up a lot of space and gave off a great deal of heat just like light bulbs do.  The ENIAC led to other vacuum tube type computers like the EDVAC (Electronic Discrete Variable Automatic Computer) and theUNIVAC I (UNIVersal Automatic Computer).
        The vacuum tube was an extremely important step in the advancement of computers.  Vacuum tubes were invented the same time the light bulb was invented by Thomas Edison and worked very similar to light bulbs.  It's purpose was to act like an amplifier and a switch.  Without any moving parts, vacuum tubes could take very weak signals and make the signal stronger (amplify it).  Vacuum tubes could also stop and start the flow of electricity instantly (switch).  These two properties made the ENIAC computer possible.
        The ENIAC gave off so much heat that they had to be cooled by gigantic air conditioners.  However even with these huge coolers, vacuum tubes still overheated regularly.  It was time for something new. 

The Second Generation:  1959-1964 (The Era of the Transistor)

   The transistor computer did not last as long as the vacuum tube computer lasted, but it was no less important in the advancement of computer technology.  In 1947 three scientists, John Bardeen,William Shockley, and Walter Brattain working at AT&T's Bell Labs invented what would replace the vacuum tube forever.  This invention was the transistor which functions like a vacuum tube in that it can be used to relay and switch electronic signals.
        There were obvious differences between the transisitor and the vacuum tube.  The transistor was faster, more reliable, smaller, and much cheaper to build than a vacuum tube.  One transistor replaced the equivalent of 40 vacuum tubes.  These transistors were made of solid material, some of which is silicon, an abundant element (second only to oxygen) found in beach sand and glass.  Therefore they were very cheap to produce.  Transistors were found to conduct electricity faster and better than vacuum tubes.  They were also much smaller and gave off virtually no heat compared to vacuum tubes.  Their use marked a new beginning for the computer.  Without this invention, space travel in the 1960's would not have been possible.  However, a new invention would even further advance our ability to use computers. 

 The Third Generation:  1965-1970 (Integrated Circuits - Miniaturizing the Computer)

       Transistors were a tremendous breakthrough in advancing the computer.  However no one could predict that thousands even now millions of transistors (circuits) could be compacted in such a small space.  The integrated circuit, or as it is sometimes referred to as semiconductor chip, packs a huge number of transistors onto a single wafer of siliconRobert Noyce of Fairchild Corporation and Jack Kilby ofTexas Instruments independently discovered the amazing attributes of integrated circuits.  Placing such large numbers of transistors on a single chip vastly increased the power of a single computer and lowered its cost considerably.
        Since the invention of integrated circuits, the number of transistors that can be placed on a single chip has doubled every two years, shrinking both the size and cost of computers even further and further enhancing its power.  Most electronic devices today use some form of integrated circuits placed on printed circuit boards-- thin pieces of bakelite or fiberglass that have electrical connections etched onto them -- sometimes called amother board. 
        These third generation computers could carry out instructions in billionths of a second.  The size of these machines dropped to the size of small file cabinets. Yet, the single biggest advancement in the computer era was yet to be discovered. 

The Fourth Generation:  1971-Today (The Microprocessor)

        This generation can be characterized by both the jump to monolithic integrated circuits(millions of transistors put onto one integrated circuit chip) and the invention of the microprocessor (a single chip that could do all the processing of a full-scale computer).  By putting millions of transistors onto one single chip more calculation and faster speeds could be reached by computers.  Because electricity travels about a foot in a billionth of a second, the smaller the distance the greater the speed of computers.
        However what really triggered the tremendous growth of computers and its significant impact on our lives is the invention of the microprocessor.  Ted Hoff, employed by Intel (Robert Noyce's new company) invented a chip the size of a pencil eraser that could do all the computing and logic work of a computer.  The microprocessor was made to be used in calculators, not computers.  It led, however, to the invention of personal computers, or microcomputers.
        It wasn't until the 1970's that people began buying computer for personal use.  One of the earliest personal computers was the Altair 8800 computer kit.  In 1975 you could purchase this kit and put it together to make your own personal computer.  In 1977 the Apple II was sold to the public and in 1981 IBM entered the PC (personal computer) market.
        Today we have all heard of Intel and its Pentium® Processors and now we know how it all got started.  The computers of the next generation will have millions upon millions of transistors on one chip and will perform over a billion calculations in a single second.  There is no end in sight for the computer movement.