Hardware Concepts
What is Computer ?A computer is an electronic device that processes input data and produces result (output) according to a set of instructions called program. A computer performs basically five major functions irrespective of its size and make.
1. It accepts data or instructions by way of input
2. It stores data
3. It processes data as required by the user
4. It controls operations of a computer
5. It gives results in the form of output
How Computer works?
The above diagram describes the basic layout of a computer. A computer receives data and instructions through "Input Devices" which get processed in Central Processing Unit, "CPU" and the result is shown through "Output Devices". The "Main / primary Memory" and "Secondary / Auxiliary Memory" are used to store data inside the computer.
Input: An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance.
Secondary Memory (Storage): The secondary memory is used to store the data permanently in the computer. The secondary storage devices are usually as follows: hard disk drives – this is the most common type of storage device that is used in almost all the computer systems. The other ones include the floppy disk drives, the CD ROM, and the DVD ROM. The flash memory, the USB data card etc.
Main Memory: The Primary memory or Main Memory is of two types; one is RAM (Random Access Memory) and the other one is ROM (Read Only Memory). The RAM is the volatile memory and the ROM is the non-volatile memory. The volatile memory is the kind of the memory that is erasable and contents will be lost, if power is switched off.
Output: This is the process of producing results from the data for getting useful information. Similarly the output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. Again the output is also stored inside the computer for further processing.
Arithmetic Logical Unit (ALU): In computing, an arithmetic and logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers Control Unit (CU): The control unit coordinates the components of a computer system. It fetches the code of all of the instructions in the program. It directs the operation of the other units by providing timing and control signals. All computer resources are managed by the CU. It directs the flow of data between the Central Processing Unit (CPU) and the other devices Central Processing Unit (CPU): The ALU and the CU of a computer system are jointly known as the central processing unit. You may call CPU as the brain of any computer system. It is just like brain that takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.
Memory There are two kinds of computer memory: primary and secondary. Primary memory is accessible directly by the CPU. RAM is an example of primary memory. As soon as the computer is switched off the contents of the primary memory is lost. You can store and retrieve data much faster with primary memory compared to secondary memory. Secondary memory such as floppy disks, magnetic disk, etc., is located outside the computer. Primary memory is more expensive than secondary memory.
Random Access Memory (RAM): A random-access device allows stored data to be accessed in very nearly the same amount of time for any storage location, so data can be accessed quickly in any random order. This memory is a volatile memory. The two main forms of modern RAM are static RAM (SRAM) and dynamic RAM (DRAM). .
Read Only Memory (ROM): Read-only memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified or can be modified with difficulty, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware) . ROM do not lose their content on failure of power supply.
INPUT DEVICES
Input devices are necessary to convert our information or data in to a form which can be understood by the computer. A good input device should provide timely, accurate and useful data to the main memory of the computer for processing followings are the most useful input devices.
Keyboard: A 'keyboard' is a human interface device which is represented as a layout of buttons. Each button, or key, can be used to either input a linguistic character to a computer, or to call upon a particular function of the computer. In normal usage, the keyboard is used to type text and numbers while in a modern computer, the interpretation of key press is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports the key-presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features. Generally a QWERTY keyboard is used. The term QWERTY indicates the KEYS-LAYOUT on the keyboard. In general a keyboard has Number keys (0-9), Function Keys (F1 to F12), Direction keys, and Control keys along with Alphabet keys.
Mouse:
A mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. The mouse's motion typically translates into the motion of a cursor on a display, which allows for fine control of a Graphical User Interface. A mouse primarily comprises of three parts: the buttons, the handling area, and the rolling object. Generally Optical mouse is used in PCs. Now days Wireless (card less) mouse are also available in the market.
Light Pen:
A light pen, also called a selector pen, is a computer input device in the form of a light- sensitive wand used in conjunction with a computer's CRT display. It allows the user to point to displayed objects or draw on the screen in a similar way to a touch screen but with greater positional accuracy.
Scanner:
An image scanner or scanner is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are flatbed scanner where the document is placed on a glass window for scanning. Hand-held scanners, where the device is moved by hand on the paper.
Smart Card Reader:
A smart card, chip card, or integrated circuit card (ICC) is any pocket-sized card with embedded integrated circuits which may contain some information. It is a common used in Smart card reader device to read the stored information. Generally it is used as digital Identification or authorization purposes of a person. Barcode Reader:
A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones.
Optical Character Recognition (OCR):
Optical character recognition, usually abbreviated to OCR, It is used to convert images of handwritten, typewritten or printed text into machine-encoded text. . It is widely used to convert books and documents into electronic files, to computerize a record-keeping system in an office, or to publish the text on a website.
OUTPUT DEVICES
Visual Display Unit:
A monitor or display (also called screen or visual display unit) is an electronic visual display for computers. It looks like a TV.The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube (CRT).
Printer:
A printer is a peripheral which produces a hardcopy representation of an electronic document on physical media such as paper. Multifunction printers (MFPs) or All-in-one Printer include a scanner and can copy paper documents or send a fax. Depending on their speed and mechanism of printing, printers are classified as impact and non-impact printers.
Impact printers: use the familiar typewriter approach of hammering a typeface against the paper and inked ribbon. Dot-matrix printers are of this type.
Non-impact printers: do not hit or impact a ribbon to print. They use electro-static chemicals and ink-jet technologies. Laser printers and Ink-jet printers are of this type. This type of printers can produce color printing and elaborate graphics.
Ink-jet (bubble-jets) printers: Ink-jets(bubble-jets) printers spray ionized tiny drops of ink onto a page to create an image. This is achieved by using magnetized plates which direct the ink's path onto the paper in the desired pattern. Almost all ink-jets offer a color option as standard, in varying degrees of resolution.
Laser Printers: Laser printers operate by shining a laser beam to produce an image on a drum. The drum is then rolled through a toner, and the electrically charged portions of the drum pick up ink. Finally, using a combination of heat and pressure, the ink on the drum is transferred onto the page. Laser printers print very fast, and cartridges work for a long time. Color laser printers use the same toner-based printing process as black and white (B/W) laser printers, except that they combine four different toner colors.
Plotters: Plotters are large-scale printers that are very accurate at reproducing line drawings. They are commonly used for technical drawings such as engineering drawings or architectural blueprints. The two basic types of plotters are called flatbed plotters and drum plotters. Flatbed plotters are horizontally aligned with a flat surface to which a piece of paper is attached. The paper remains stationary and the printer moves pens across the paper to draw the image. Drum plotters, also called upright plotters, are vertically positioned. They have a drum that the paper rolls on. Drum plotters usually make more noise and are more compact than flatbed plotters.
Secondary Storage Device:
It is also referred as external memory and auxiliary storage. It is a storage medium that holds information until it is deleted or overwritten. For example, a floppy disk drive and hard disk drive are both good examples of secondary storage devices.
Magnetic Tapes: The Magnetic Tapes is the Type of Secondary Storage Device and this Device is used for taking back up of data. Magnetic Tapes are used for accessing the data into the Sequential form.
Hard Disk : It is made from the thin metal platter which is coated on the both sides of the magnetic Disks. A hard disk contains many Plates made from the Magnetic Materials. The hard disk also contains a head which is used for both Reading and Writing the Data from the Hard Disks. The Plate of the hard disk is divided into the Tracks and Sectors and the collection of Tracks makes a Cylinder.
Floppy Diskette:
A floppy disk, or diskette, is a storage medium composed of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier. They are read and written by a floppy disk drive (FDD). Floppy disks may be as 5.25 or 3.5 inch size.
CD & DVD:
Compact Disk (CD) and Digital Versatile/Video Disc (DVD) is an optical disc storage format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions. A CD may have 700 MB data where as a DVD may have 4.7 GB storage.
CD-ROM and DVD-ROM are Pre-recorded CDs and DVDs use for mass-production of audio or video contents. These are called ROM because data can only be read and not written nor erased. Blank recordable CDs and DVDs discs (CD-R and DVD-R) can be recorded once using a Recorder/ Writer. Rewritable CDs and DVDs (CD-RW and DVD-RW) can be recorded and erased multiple times. The new technology which offers more data capacity is called Blue Ray Disks.
Flash Drives:
A USB flash drive is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. These small plug-and-play drives are removable, re-writable, and great for storing personal and professional data, as many are hardware-encrypted devices for ultimate security.
Memory Card:
A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players and video game consoles. They are small, re-recordable, and able to retain data without power. There are a number of memory cards on the market, including the SD card (secure digital card), the CF card (Compact Flash card), the Smart Media card, the Memory Stick, and the Multimedia Card.
Online Storage: Also called "remote backup," or "cloud storage," online storage sites allow you to store information on a company's servers. SugarSync, Dropbox, IDrive and numerous other sites provide these services for free up to 5 GB space.
No comments:
Post a Comment