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Friday, January 23, 2015

Hardware Basic

Computer Hardware            By - Solanki Sir

What is Hardware -  Computer hardware refers to the physical parts or components of a computer such as the monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound cards, memory, motherboard and chips), etc. all of which are physical objects that can be touched.
There are many types of computer devices –
·         Input devices
·         Output devices
·         Processing devices
·         Output devices
Input devices
Following are few of the important input devices which are used in a computer:

·       Keyboard - A keyboard is the set of typewriter-like keys used to enter data into a computer.Keyboards are similar to typewriter keyboards but contain additional keys.
It is a text base input device that allows the user to input alphabets, numbers and other characters. It consists of a set of keys mounted on a board
·         ·  alphanumeric keys -- letters and numbers
·         ·  punctuation keys -- comma, period, semicolon, and so on.
·       ·  special keys -- function keys, control keys, arrow keys, Caps Lock key, and so on.

Keyboard layout - QWERTY, AZERTY, Dvorak


Punctuation keys All of the keys associated with punctuation such as the comma, period, semicolon, brackets, parenthesis and so on. Also, all of the mathematical operators such as the plus sign, minus sign, and equal sign.
It is similar to the „return‟ key of the typewriter and is used to execute a command or
It is used to enter a space at the current cursor location.
This key is used to move the cursor one position to the left and also delete the character in
that position.
It is used to delete the character at the cursor position.

Insert key is used to toggle between insert and overwrite mode during data entry.
This key is used to type capital letters when pressed along with an alphabet key. Also used to
type the special characters located on the upper-side of a key that has two characters defined
on the same key.
Caps Lock
Cap Lock is used to toggle between the capital lock feature. When „on‟, it locks the
This key is usually used to negate a command. Also used to cancel or abort executing

·       Mouse - a small handheld device which is moved across a mat or flat surface to move the cursor on a computer screen.
The most conventional kind of mouse has two buttons on top: the left one being used most
Mouse Actions:-
Left Click: Used to select an item.
Double Click: Used to start a program or open a file.

Right Click: Usually used to display a set of commands.
Drag and Drop: It allows you to select and move an item from one location to another. To
achieve this place the cursor over an item on the screen, click the left mouse button and
while holding the button down move the cursor to where you want to place the item, and

then release it.

·       Joy Stick-
joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticksare often used to control video games, and usually have one or more push-buttons whose state can also be read by the computer.
·       Light pen
  1. A light 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 touchscreen but with greater positional accuracy.
·       Track Ball - 
  1. trackball is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes—like an upside-down mouse with an exposed protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to move a pointer.
·       Scanner - Scanner is an input device used for direct data entry from the source document into the computer
system. It converts the document image into digital form so that it can be fed into the computer.
Capturing information like this reduces the possibility of errors typically experienced during large
data entry.
1. Flatbed scanners: also called desktop scanners, are the most versatile and commonly used scanners. In
fact, this article will focus on the technology as it relates to flatbed scanners.
2. Handheld scanners: use the same basic technology as a flatbed scanner, but rely on the user to move them instead of a motorized belt. This type of scanner typically does not provide good image quality. However, it can be useful for quickly capturing text.

MICR  --Magnetic Ink Character Recognition is a character recognition system that uses special ink and characters. When a document that contains this ink needs to be read, it passes through a machine, which magnetizes the ink and then translates the magnetic information into characters. 
MICR technology is used by banks. Numbers and characters found on the bottom of checks (usually
 containing the check number, sort number, and account number) are printed using Magnetic Ink. To print Magnetic Ink need, you need a laser printer that accepts MICR toner. MICR provides a secure, high-speed method of scanning and processing information.
MICR, is a character recognition technology used primarily by the banking industry to facilitate the
processing of cheques. The technology allows computers to read information (such as account numbers) off printed documents. Unlike barcodes or similar technologies, however, MICR codes can be easily read by humans

MICR characters are printed in special typefaces with a magnetic ink or toner, usually containing iron oxide. As a machine decodes the MICR text, it first magnetizes the characters in the plane of the paper. Then the characters are passed over a MICR read head, a device similar to the playback head of a tape recorder. As each character passes over the head it produces a unique waveform that can be easily identified by the system.  The use of magnetic printing allows the characters to be read reliably even if they have been overprinted or obscured by other marks, such as cancellation stamps and signature. The error rate for the magnetic scanning of a typical check is smaller than with optical character recognition systems. For well printed MICR documents, the "can't read" rate is usually less than 1% while the substitution rate (misread rate) is in the order of 1 per 100,000 characters.

OCR  Optical character recognition, usually abbreviated to OCR, is the mechanical or electronic translation of scanned 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. OCR makes it possible to edit the text, search for a word or phrase, store it more compactly, display or print a copy free of scanning artifacts, and apply techniques such as machine translation, text-to-speech and text mining to it. OCR is a field of research in pattern recognition, artificial intelligence and computer vision.
·       Graphic Tablet
·       Microphone
·       Magnetic Ink Card Reader(MICR)
·       Optical Character Reader(OCR)
·       Bar Code Reader
·       Optical Mark Reader(OMR)
·       Biometric
·       SRS
·       MSR
·       Cemra
·       Microphone
·       Webcam

Output Devices –
Monitors, commonly called as Visual Display Unit (VDU)
·         CRTThe cathode ray tube (CRT) is a vacuum tube containing one or more electron guns, and a fluorescent screen used to view images.
·         LCD -A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.
·         LED - An LED monitor is basically the new version of the LCD monitor that you connect to your computer.
·         OLED -The OLED display is based an organic substance used as the semiconductor material in light-emitting diodes (LEDs). The display is created by sandwiching organic thin films between two conductors. When an electrical current is applied to this structure, it emits a bright light.
·         AMOLED (active-matrix organic light-emitting diode) is a display technology for use in mobile devices and television.

Graphics card - A video card (also called a video adapter, display card, graphics card, graphics board, display adapter,graphics adapter or frame buffer[1] and sometimes preceded by the word discrete or dedicated to emphasize the distinction between this implementation and integrated graphics) is an expansion card which generates a feed of output images to a display (such as a computer monitor)
Example  -
*(Color Graphics Adapter)
320 x 200
*(Enhanced Graphics Adapter)
640 x 350

(Video Graphics Array)
640 x 480
(Super Video Graphics Array)
800 x 600
(High Definition Television 720i/p)
1280 x 720
(Extended Graphics Array)
1024 x 768
(Wide Extended Graphics Array)
1366 x 768
(Super Extended Graphics Array)
1280 x 1024
(Super Extended Graphics Array+)
1400 x 1050
(Wide Super Extended Graphics Array)
1600 x 1024
(Wide Super Extended Graphics Array+)
1680 x 1050
(High Definition Television 1080i/p)
1920 x 1080
(Ultra Extended Graphics Array)
1600 x 1200

·       a pixel is a single point in a graphic image

Printer -  A printer is an output device that produces text and graphics on a physical medium such as paper. Printed information is often called hard copy because the information exists physically and is a more permanent form of output than that presented on a VDU (Monitor). Printers can be grouped into impact and non-impact printers.
Impact printer - An impact printer forms characters and graphics on a piece of paper bystriking a mechanism against an ink ribbon that physically contacts the paper.
Nonimpact printer-  A non-impact printer forms characters and graphics on a piece of paperwithout actually striking the paper.
NOTE -- The printing speed of a printer is usually expressed in pages per minute(ppm). Printer resolution is often expressed in dpi (dots per inch). The larger the number, the higher the resolution.
Daisy Wheel printer- A daisywheel printer is an impact printer that uses a wheel as a print head.As the wheel rotates, a hammer strikes the backside of the spoke and presses it against the paper to print a character.
Advantages of a daisywheel printer
 Can print letter quality characters.
Disadvantages of a daisywheel printer
·         Printing speed is very slow.
Cannot print graphics.
Dot-Matrix Printer- A dot-matrix printer is an impact printer that produces printed images with a print head striking mechanism. Most dot-matrix printers use continuous-form paper. A higher number of pins on the print head means more dots are printed, which results in higher print quality (i.e., a 24-pin printer has better print quality than a 9-pin printer).
The speed of a dot-matrix printer is normally measured by the number of characters per second (cps) it can print.
Advantages of dot-matrix printers
·         Dot-matrix printers can print multipart forms.
·         Dot-matrix printers can withstand dusty environment, vibrations, and extreme temperature.
Disadvantages of dot-matrix printers
·         Dot-matrix printers are generally noisy because of the striking mechanism.
·         Print quality of dot-matrix printers is not as good as those from ink-jet printers and laser printers.
Line Printer - A line printer is a high-speed impact printer that prints an entire line at a time. The speed of a line printer is measured by the number of lines per minute (lpm) it can print. Line printers are often used with mainframes, minicomputers, or with a network in applications such as manufacturing, distribution, or shipping.
Laser Printer- The mechanism of how a laser printer works is similar to a photocopier. Laser printers are also known as page printers because they process and store the entire page before they actually print it. Most laser printers today can print text and graphics in very high quality resolutions, ranging from 600 dpi to 1200 dpi. Laser printers can print text at speeds of four to over thirty pages per minute.
Advantages of laser printers include
 Laser printers are generally quiet and fast.
·         Laser printers can produce high quality output on ordinary papers.
·         The cost per page of toner cartridges is lower than other printers.
Disadvantages of laser printers include
·         The initial cost of laser printers can be high.
·         Laser printers are more expensive than dot-matrix printers and ink-jet printers
A plotter is a large printer that generates high-quality documents by moving ink pens over the surface of a page. Plotters are particularly useful to engineers and architects, as they produce high-quality blueprints, maps, and floor plans.
Two basic types of plotters are pen plotters and X-Y plotters.
Advantages of plotters include
·         Can print on large printers.
·         High quality printing
Other output devices
·         Projector
·         LCD Projection Panels
·         Computer Output Microfilm (COM)
·         Speaker(s)
Thermal printerA printer that uses heat to transfer an impression onto paper.
For example – ATM slip, bus ticket. Etc
Both Input-OutPut Devices:
1.     Modems
2.     Network cards
3.     Touch Screen
      4. Headsets (Headset consists of Speakers and Microphone. 
           Speaker act Output Device and     Microphone act as Input 
     5. Facsimile (FAX)  (It has scanner to scan the document and also 
           have printer to Print the  document)
     6.Audio Cards / Sound Card

Central Processing Unit (CPU)
A hardware device that performs computing and manipulating functions, and controlling of other hardware devices. It utilizes three associated elements: the Arithmetic/Logic Unit (ALU), Control Unit, and Registers.

• Arithmetic/Logic Unit (ALU): Performs mathematical calculations (addition, subtraction, etc.) and makes logical (true/false) comparisons.

• Control Unit: Sequentially accesses program instructions, decodes them, and coordinates flow of data in/out of ALU, registers, primary and secondary storage, and various output devices.

• Registers: High-speed storage areas used to temporarily hold small units of program instructions and data that are being transferred from the primary storage to the CPU for processing.

Types of Registers are as Followings

Accumulator Register- Which stores the intermediate result of arithmetic and logical operations.

 MAR stand for Memory Address Register
This register holds the memory addresses of data and instructions. This register is used to access data and instructions from memory during the execution phase of an instruction. Suppose CPU wants to store some data in the memory or to read the data from the memory. It places the address of the-required memory location in the MAR.


Program Counter – which contain the address of the next instruction to process.


Instruction Register – IR – which contain the current instruction being processed.

·         The clock speed is currently clocked in KiloHertz (Hz), MegaHertz (MHz), and GigaHertz (GHz).

·         Fetch > decode > execute > store

MotherboardA motherboard (sometimes alternatively known as the mainboard, system board, planar board or logic board, or colloquially, a mobo) is the main printed circuit board (PCB) found in computersand other expandable systems.

Motherboard Bus - The motherboard bus is a set of wires that allows one part of the motherboard to connect and communicate with other parts of the motherboard, including the central processing unit (CPU). 

          The motherboard bus can be one of two types — internal and external.
         An internal bus serves as the communication highway of the motherboard. It links the different parts of the computer to the CPU and the main memory. Its primary task is to send data and instructions to the different parts within the motherboard, including the external bus.
The external type of motherboard bus, which is also known as the expansion bus, serves as the interface for peripheral devices like hard disks, CD-ROM drives, and flash drives to get connected to the CPU. The shape of each interface is unique. This prevents plugging a device to a wrong port, which could cause damage to the device while being connected to the CPU.


·         A CPU socket - the actual CPU is directly soldered onto this socket. Since high speed CPUs generate a lot of heat, there are heat sinks and mounting points for fans right next to the CPU socket.
·         A power connector to distribute power to the CPU and other components.
·         Slots for the system's main memory, typically in the form of DRAM chips.
·         A chip forms an interface between the CPU, the main memory and other components. On many types of motherboards this is referred to as the Northbridge. This chip also contains a large heat sink.
·         A second chip controls the input and output (I/O) functions. It is not connected directly to the CPU but to the Northbridge. This I/O controller is referred to as the Southbridge. The Northbridge and Southbridge combined are referred to as the chipset.
·         Several connectors, which provide the physical interface between input and output devices and the motherboard. The Southbridge handles these connections.
·         Slots for one or more hard drives to store files. The most common types of connections are Integrated Drive Electronics (IDE) and Serial Advanced Technology Attachment (SATA).
·         A Read-only memory (ROM) chip, which contains the firmware, or startup instructions for the computer system. This is also called the BIOS.
·         A slot for a video or graphics card. There are a number of different types of slots, including Accelerated Graphics Port (AGP) and Peripheral Component Interconnect Express (PCIe).
·         Additional slots to connect hardware in the form of Peripheral Component Interconnect (PCI) slots.


What is a Port- is a physical docking point using which an external device can be connected to the computer.

A port has the following characteristics:
·        External devices are connected to a computer using cables and ports.
·        Ports are slots on the motherboard into which a cable of external device is plugged in.
·        Examples of external devices attached via ports are mouse, keyboard, monitor, microphone, speakers etc.
Computer Ports
Following are few important types of ports:
Serial Port
  • Used for external modems and older computer mouse
  • Two versions : 9 pin, 25 pin model
  • Data travels at 115 kilobits per second
Parallel Port
  • Used for scanners and printers
  • Also called printer port
  • 25 pin model
  • Also known as IEEE 1284-compliant Centronics port
PS/2 Port
·        Used for old computer keyboard and mouse
·        Also called mouse port
·        Most of the old computers provide two PS/2 port, each for mouse and keyboard
·        Also known as IEEE 1284-compliant Centronics port
Universal Serial Bus (or USB) Port
·        It can connect all kinds of external USB devices such as external hard disk, printer, scanner, mouse, keyboard etc.
·        It was introduced in 1997.
·        Most of the computers provide two USB ports as minimum.
·        Data travels at 12 megabits per seconds
·        USB compliant devices can get power from a USB port
VGA Port
·        Connects monitor to a computer's video card.
·        Has 15 holes.
·        Similar to serial port connector but serial port connector has pins, it has holes.
Power Connector
·        Three-pronged plug
·        Connects to the computer's power cable that plugs into a power bar or wall socket
Firewire Port
·        Transfers large amount of data at very fast speed.
·        Connects camcorders and video equipments to the computer
·        Data travels at 400 to 800 megabits per seconds
·        Invented by Apple
·        Three variants : 4-Pin FireWire 400 connector, 6-Pin FireWire 400 connector and 9-Pin FireWire 800 connector
Modem Port
  • Connects a PC's modem to the telephone network
Ethernet Port
·        Connects to a network and high speed Internet.
·        Connect network cable to a computer.
·        This port resides on an Ethernet Card.
·        Data travels at 10 megabits to 1000 megabits per seconds depending upon the network bandwidth.
Game Port
  • Connect a joystick to a PC
  • Now replaced by USB.
Digital Video Interface, DVI port
·        Connects Flat panel LCD monitor to the computer's high end video graphic cards.
·        Very popular among video card manufacturers.
·        Connect microphone, speakers to sound card of the computer

Switched Mode Power Supplies (SMPS) -- SMPS stands for Switched Mode Power Supply. It is basically a power supply unit in everything from TVs to LCD monitors, camcorders to printers and fax machines. It's been in use in the military before it made its way into consumer electronics. 


Uninterruptible power supply (UPS) - a device that allows your computer to keep running for at least a short time when the primary power source is lost. It also provides protection from power surges.

     Match the following terms with their meanings:
            I.    port                        A. provides power to and controls all the expansion boards
            II.   CRT                       B. a type of monitor
            III. NIC                        C. the place on the system where a peripheral device is attached
            IV. motherboard          D. enables a computer to connect to other computers
            V.  nanosecond           E. one billionth of a second
Answer: C, B, D, A, E             Reference: Multiple locations in chapter                     Difficulty: Moderate
        Match the following ports with the devices most likely to be connected to them:
            I.    VGA port               A. flash drive
            II.   parallel port           B. monitor
            III. serial port               C. printer
            IV. Ethernet port          D. modem
            V.  USB port                E. DSL or cable modem
Answer: B, C, D, E, A             Reference: Ports                                                          Difficulty: Challenging
      Match the following acronyms with their functions:
            I.    CPU                       A. type of technology used on a flat-screen monitor
            II.   RAM                      B. standard keyboard layout
            III. ROM                      C. temporary storage, also known as primary storage
            IV. LCD                       D. controls all the other functions performed by the computer’s other components                                                    and processes all the commands issued to it by software instructions
            V.  QWERTY              E. permanent storage that is not erased when the computer’s power is turned off
Answer: D, C, E, A, B             Reference: Multiple locations in chapter                     Difficulty: Challenging
         Match the following terms with their meanings:
            I.    stylus                                 A. an input device used to enter data on a PDA
            II.   hertz (Hz)                          B. the clearness or sharpness of an image
            III. resolution                           C. temporary
            IV. volatile                               D. a unit of frequency indicating cycles per second
            V.  system unit                        E. contains the central electronic components of the computer
Answer: A, D, B, C, E             Reference: Multiple locations in chapter                     Difficulty: Easy

   Match the following terms with their meanings:
            I.    peripheral devices  A. an example of permanent storage
            II.   modem port           B. external devices that exchange data with the computer through ports
            III. dot-matrix              C. an example of an impact printer
            IV. ergonomics            D. an example of a connectivity port
            V.  hard disk drive       E. the science involved with minimizing the risk of injury or discomfort
Answer: B, D, C, E, A             Reference: Multiple locations in chapter                     Difficulty: Easy

      Match the following terms with their meanings:
            I.    CD-ROM                           A. an example of a nonimpact printer
            II.   audio ports                         B. a type of LCD monitor
            III. pixels                                 C. used to connect headphones, microphones, and speakers to the                                                                             computer
            IV. active-matrix display         D. an example of read-only storage
            V.  ink-jet                                E. a CRT screen is made up of millions of these
Answer: D, C, E, B, A             Reference: Multiple locations in chapter                     Difficulty: Easy

        Match the following terms with their meanings:
            I.    refresh rate                                    A. measurement of printing speed
            II.   dot pitch                                        B. 0.28 mm or less is the sign of a good CRT monitor
            III. thermal                                          C. commonly between 75 and 85 hertz
            IV. ppm                                               D. measurement of printer resolution
            V.  dpi                                                 E. emerging technology for mobile and portable printing
Answer: C, B, E, A, D