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.
· 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.
or
Types of
Registers are as Followings
Accumulator Register- Which stores the intermediate result of
arithmetic and logical operations.
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
Motherboard – A 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).
What is a Port- is a physical docking point using which an external device can be
connected to 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.
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.
or
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
· · 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.
Enter
It is similar to the „return‟ key of the typewriter and is
used to execute a command or
program.
Spacebar
It is used to enter a space at the current cursor location.
Backspace
This key is used to move the cursor one position to the left
and also delete the character in
that position.
Delete
It is used to delete the character at the cursor position.
Insert
Insert key is used to toggle between insert and overwrite
mode during data entry.
Shift
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
Esc
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
frequently.
Mouse Actions:-
Left Click: Used to select an item.
Double Click: Used to start a program or open a file.
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-
A 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.
A 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 -
· Track Ball -
· Scanner -
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.
TYPES OF SCANNER
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
Monitors, commonly called as Visual Display Unit (VDU)
·
CRT - The 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
-
|
· 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
Plotter
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)
etc
Thermal printer - A 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
device)
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
Motherboard – A 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.
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.
Sockets
·
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
