Basic Hardware Unit-Input Unit,Memory auxillary,CPU,Output Units

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Basic Units of Computer



Input devices are used to feed data into the computer. There are different kinds of input devices.

1) Keyboard

The keyboard is very much like a standard typewriter keyboard with few additional keys. When any keys pressed it sends electronic signal with unique identification to the computer operating system detects these identification with the help of map. Other than regular keys there are functions keys, Ctrl key, Alt key, etc. The additional keys are included to perform certain special functions such as loading a program or editing a text. There are 101 keys in standard keyboard but now a days keyboard with more than 101 keys are also available.

2) Mouse

It is an input device & is used to position the pointer on the screen. It is a small palm size box. Its movement on a flat surface moves pointer in the same direction as the movement of the mouse. The box contains a ball underneath, which senses the movement & transmits it to the computer. Computer process the input & places the mouse pointer accordingly. There are two buttons(left button & right button) in standard mouse, used to give commands. Now a days it is more advance than keyboard.In other words we can say mouse is working just like a keyboard.

3) Trackball

It basically work like a mouse of computer on laptop.Same work which a mouse can do on computer can also be performed by the trackball.

4) Scanner

It is one of the device, mostly used in designing etc, provides input to computer. Further, these inputs are used for processing & manipulation. There are some specific scanners built for special purpose like OCR, MICR or BCR.

1) Optical Character Reader(OCR) Optical character reader is an input device used to read any printed text. OCR scans text optically character by character, converts them into a machine readable code & store the text on the system memory. It can read at a rate of upto 1,400 characters per second.

2) Magnetic Ink Character Recognize(MICR)

MICR can identify characters printed with a special ink that contain particles of magnetic materials, MICR is used mainly in the banking industry to read cheques. Since MICR system can recognize only certain character styles, the character styles, the characters have to be accurately formed.

3) Bar Code Reader(BCR)

BCR is a device which reads light & dark lines of different thickness. Bar Codes are used to label different products. Bar Code is the method of coding books etc. Uniquely, BCR is used to decide these lines & identify the product.


Types of Output Hard copy: printed on paper or other permanent media

Soft copy: displayed on screen or by other non-permanent means CPU stands for Central Processing Unit

This is the part of the computer that does the "thinking." Computer hardware is the physical part of a computer, including its digital circuitry, as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and hardware data, which are "soft" in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is, therefore, "firm" rather than just "soft"). Typical PC hardware A typical personal computer consists of a case or chassis in a tower shape (desktop) and the following parts:

Internals of typical personal computer. Inside a Custom Computer. Motherboard

  • Motherboard - It is the "body" or mainframe of the computer, through which all other components interface.

Central processing unit (CPU) - Performs most of the calculations which enable a computer to function, sometimes referred to as the "brain" of the computer. Computer fan - Used to lower the temperature of the computer; a fan is almost always attached to the CPU, and the computer case will generally have several fans to maintain a constant airflow. Liquid cooling can also be used to cool a computer, though it focuses more on individual parts rather than the overall temperature inside the chassis. '* Random Access Memory (RAM)' - Fast-access memory that is cleared when the computer is powered-down. RAM attaches directly to the motherboard, and is used to store programs that are currently running. * Firmware is loaded from the Read only memory ROM run from the Basic Input-Output System (BIOS) or in newer systems Extensible Firmware Interface (EFI) compliant

Power supply Main article: Computer power supply A case control, and (usually) a cooling fan, and supplies power to run the rest of the computer, the most common types of power supplies are AT and BabyAT (old) but the standard for PCs actually are ATX and Micro ATX.

Storage controllers Controllers for hard disk, CD-ROM and other drives like internal Zip and Jaz conventionally for a PC are IDE/ATA; the controllers sit directly on the motherboard (on-board) or on expansion cards, such as a Disk array controller. IDE is usually integrated, unlike SCSISmall Computer System Interface which is found in most servers. The floppy drive interface is a legacy MFM interface which is now slowly disappearing. All these interfaces are gradually being phased out to be replaced by SATA and SAS.

Video display controller Main article: Graphics card Produces the output for the visual display unit. This will either be built into the motherboard or attached in its own separate slot (PCI, PCI-E, PCI-E 2.0, or AGP), in the form of a Graphics Card.

Removable media devices Main article: Computer storage CD (compact disc) - the most common type of removable media, inexpensive but has a short life-span. CD-ROM Drive - a device used for reading data from a CD. CD Writer - a device used for both reading and writing data to and from a CD. DVD (digital versatile disc) - a popular type of removable media that is the same dimensions as a CD but stores up to 6 times as much information. It is the most common way of transferring digital video. DVD-ROM Drive - a device used for reading data from a DVD. DVD Writer - a device used for both reading and writing data to and from a DVD. DVD-RAM Drive - a device used for rapid writing and reading of data from a special type of DVD. Blu-ray - a high-density optical disc format for the storage of digital information, including high-definition video. BD-ROM Drive - a device used for reading data from a Blu-ray disc. BD Writer - a device used for both reading and writing data to and from a Blu-ray disc. HD DVD - a high-density optical disc format and successor to the standard DVD. It was a discontinued competitor to the Blu-ray format. Floppy disk - an outdated storage device consisting of a thin disk of a flexible magnetic storage medium. Zip drive - an outdated medium-capacity removable disk storage system, first introduced by Iomega in 1994. USB flash drive - a flash memory data storage device integrated with a USB interface, typically small, lightweight, removable, and rewritable. Tape drive - a device that reads and writes data on a magnetic tape, usually used for long term storage.

Internal storage Hardware that keeps data inside the computer for later use and remains persistent even when the computer has no power.

Hard disk - for medium-term storage of data. Solid-state drive - a device similar to hard disk, but containing no moving parts. Disk array controller - a device to manage several hard disks, to achieve performance or reliability improvement.

Sound card Main article: Sound card Enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers have sound cards built-in to the motherboard, though it is common for a user to install a separate sound card as an upgrade.

Networking Main article: Computer networks Connects the computer to the Internet and/or other computers.

Modem - for dial-up connections Network card - for DSL/Cable internet, and/or connecting to other computers. Direct Cable Connection - Use of a null modem, connecting two computers together using their serial ports or a Laplink Cable, connecting two computers together with their parallel ports. dial up connections broad band connections

Other peripherals Main article: Peripheral In addition, hardware devices can include external components of a computer system. The following are either standard or very common.

Wheel mouseIncludes various input and output devices, usually external to the computer system

Input Main article: Input Text input devices Keyboard - a device, to input text and characters by depressing buttons (referred to as keys), similar to a typewriter. The most common English-language key layout is the QWERTY layout. Pointing devices Mouse - a pointing device that detects two dimensional motion relative to its supporting surface. Trackball - a pointing device consisting of an exposed portruding ball housed in a socket that detects rotation about two axes. Xbox 360 Controller - A controller used for Xbox 360, Which with the use of the application Switchblade(tm), can be used as an additional pointing device with the left or right thumbstick. Gaming devices Joystick - a general control device that consists of a handheld stick that pivots around one end, to detect angles in two or three dimensions. Gamepad - a general game controller held in the hand that relies on the digits (especially thumbs) to provide input. Game controller - a specific type of controller specialized for certain gaming purposes. Image, Video input devices Image scanner - a device that provides input by analyzing images, printed text, handwriting, or an object. Webcam - a low resolution 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 an electrical signals

Output Main article: Output Image, Video output devices Printer Monitor Audio output devices Speakers Headset

See also Electronics portal Computer architecture Digital circuit Green computing History of computing hardware Origins of computer terms Open hardware Optical computer DNA computing Legacy system E-waste External links HowStuffWorks

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