Transcript Laser Printers

Von Neumann Architecture
Hardware
The term hardware refers to the physical
parts of the computer.
All
components
which
are
tangible
(touchable) are called Hardware
Components of computer
There are three main Components of
computer.
1.Input devices
2.Output Devices
3.System Unit
1. INPUT DEVICES
Any hardware component used to enter data,
programs, commands, and user responses
into a computer
Examples
•
Key Board
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Pointing Devices
• Mouse
• Trackball
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Digital Camera
Webcam
Scanner etc
Keyboard
A keyboard is a set of typewriter like keys that
enables you to enter data into a computer
The keys on a computer keyboard are classified as
follow:
1. Alphanumeric keys (letters & numbers)
2. Punctuation keys (comma, semi colon etc…)
3. Special keys (function keys, control keys, arrow
keys etc..)
4. Toggle keys (keys that switches b/w two different
states like Num Lock, Caps Lock)
Keyboard
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The standard layout of letters, numbers &
punctuations is known as QWERTY keyboard
because the first six keys on the top row of
letters is spelled as QWERTY.
Another type is Dvorak Keyboard. It is
designed so that the middle row of the keys
include the most common letters. It was
designed for speed typing.
Keyboard
QWERT vs Dvorak
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A desktop computer typically have 101 to 105
keys containing alphanumeric, function &
punctuation keys.
Wireless keyboards battery powered device use
radio waves or infrared technology to transmit
data.
Pointing Devices
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A pointing device is an input device which is
used to control a pointer on a screen. Pointer
is a small symbol on a screen.
Mouse
Trackball
Joy Stick
Touchpad
And many more
Mouse
A Mouse is a pointing device that fits comfortably
under the palm of your hand. With a
mouse you can control the movement of the
pointer, often a mouse pointer, on the
screen and make selection from the screen.
The top of the mouse has one to four
Wheel Mouse
buttons; some also have a small wheel.
The bottom of the mouse is flat and
contains a mechanism that detects the
movement of the cursor.
Optical Mouse
Mouse Types
A MECHANICAL MOUSE has a rubber or metal ball
on its underside. When the ball rolls in a certain
direction, electronic circuits in the
mouse
translate the movement of the mouse into signals
the computer understands.
An OPTICAL MOUSE, by contrast, has no moving
mechanical parts inside. Instead, an optical mouse
uses devices that emit and sense light to detect
the mouse’s movement. Some uses optical sensors
and other uses laser.
Mouse Types
Wireless Mouse
Inside the Mechanical & Optical Mouse
WIRELESS MOUSE : battery powered devices that
transmit data using wireless technology, such as
radio waves or infrared light waves.
Trackball
A mechanical mouse has a ball on the bottom, a trackball
is a stationary
pointing device with a ball on its top.
The trackball can also be inserted in a small external box
near the keyboard. The ball
is rolled with the finger to move the cursor.
Some people like to think of the trackball as an upsidedown mouse with a bigger ball
at the bottom.
Joystick
Users running game software or flight and driving
simulation software often use a Joystick as pointing
device.
A joystick is a vertical lever mounted on a base. You
move the lever in different directions to control the
actions of a vehicle or player.
The lever usually includes buttons called triggers
you can press to activate certain events.
Trackpad/Touchpad
A touchpad is a small, flat, rectangular pointing
device that is sensitive to pressure and motion.
To move the pointer using a touchpad, you slide
your fingertips across the surface or the pad.
Some touchpad have one or more buttons around
the edge of the pad that work like mouse buttons.
Trackpoint/Pointing Stick
A trackpoint or pointing stick is a pressure sensitive
pointing device shaped like a
pencil eraser that is positioned between keys on the
keyboard.
To move the pointer using a pointing stick, you push
the pointing stick with your finger.
The pointer on the screen moves in the direction you
push the pointing stick.
Sound Input/ Digital Camera
SOUND INPUT
Voice input is the process of entering data by
speaking into a microphone that is attached to the
sound card on the computer.
The data can be recorded & even converted into text
using some special software like Naturally Speaking.
DIGITAL CAMERA
A digital camera allows you to take pictures and
store the photographed images digitally, instead
of on traditional film.
Digital images stored then can be edited using
some Digital Image Processing techniques.
Biometric Devices
A "biometric device" is any device that measures a
biological function or trait (genetic characteristics)
Examples
 Voice recognition
 Thumb impression
 Retina scanner
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Face recognition
2.
OUTPUT DEVICES
Any hardware component used to show results
after processing to any user. Output can be text,
Audio, Video & graphics.
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Examples
 Display device
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• Monitor
• Printer
• Plotter
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Projectors
Speakers
Headphone etc
Display Devices
A display device is simply an output device
that visually conveys text, graphics & video
information.
Information on a display device, sometimes
called soft copy exists for a temporary period
only.
Display devices include:
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CRT Monitors
LCD Monitors
Gas Plasma Monitors
Televisions
Monitors
CRT Monitors
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Similar to standard Television because it contains the CRT (Cathode Ray Tube)
CRT is a large, sealed, glass tube
The front of the tube is screen
Tiny dots of phosphorus material coat the screen
Each dot consists of red, green & blue phosphorus.
Three dots combine to make up one pixel
 Inside CRT, an electronic beam
moves back & forth across the back
site of the screen which causes the
dots on the front of the screen to glow
 The size of CRT monitors can be 14,
15, 17, 19, 21 and 22 plus more
inches which is measured diagonally.
 The actual viewable area is however, less than the diagonal size. For example,
a 21 inches monitor will have 19.8 inches viewable area
LCD Monitors
 LCD Monitors use Liquid Crystal
 A LCD contains liquid crystals between two sheets
of material
 When an electric current passes through the
crystals, they twist which causes the image to be
displayed on the screen
 LCD Monitors are the type of the flat-panel displays
 Flat Panel displays have less weight, compact screen & consume less than one third
the power consumed by CRT monitors
 The size ranges from 15, 17, 18, 20 and 21 plus more inches
 LCD Monitors typically are more expensive than CRT Monitors
 Desktop, Notebook & Handheld computers often use LCD displays
LCD or TFT:
Active Matrix or Thin Film
Transistor (TFT) Display: Higher
refresh rate & contrast
Gas Plasma Monitors
 Gas Plasma Monitors are Flat-Panel screens instead only
they use gas plasma technology, which substitutes a layer
of gas for the liquid crystal material in an LCD monitor
 When voltage is applied, the gas released UV light.
 The UV light causes the pixels on the screen to glow
 The Gas Plasma Monitors can be more than 42” wide.
 Refresh Rate: Phosphorus on the CRT Monitors must be refreshed 50 to 100
times after every second (Hz).
 Faster refresh rate causes fewer flickers on screen
 Monitor Resolution: Depends upon the number of bits to be used to display each
pixel:
 28 bits = 256 colors
 216 bits = 65536 colors
 224 to 232 bits = 16 million to 4 billion colors
Printers
A printer is an output device that produces text and graphics on a
physical medium such as paper or transparency film.
Printed information is called hard copy. And is more permanent
than a soft copy.
There are two types of printers:
1. Impact Printers
2. Non-Impact Printers
Impact Printers
An impact printer forms characters and graphics on a piece of paper by striking a
mechanism against an inked ribbon that physically contacts the paper.
Impact printers are noisy because of this striking activity.
Impact printers normally do not provide Letter Quality (LQ) printing. They are ideal
to print multipart forms because they easily can print through many layers of papers.
Printers
Two commonly used types of impact printers are:
a. Dot Matrix Printers
b. Line Printers
Dot Matrix Printers
Dot Matrix Printer produces the printed images when tiny wire pins on a print head
mechanism strike an inked ribbon.
When ribbon passes against the paper, it creates dots that form characters and graphics.
The print head can contain 9 to 24 pins. A high number of pins means the printer
prints more dots per character, which results in higher print quality.
Printers
Most dot matrix printers use continuous-form paper, in which each sheet of paper is
connected together. The pages have holes along the sides to help feed the paper.
The speed is measured by number of characters per second (CPS). It ranges from
300 to 1100 CPS
Factories & retail counters use impact printers because these printers can withstand
dusty environment, vibrations & extreme temperatures.
9-pin dot matrix printer in action
Printers
Line Printers
A line printer is a high speed impact printer that prints an entire line a time.
The speed is measured by number of lines it can print. (LPM). These printers are
capable to print 3000 LPM.
A line printer is often connected with a midrange mainframe, server or network.
Line printers are bigger in size & are more
expensive than dot matrix printers.
Non-impact Printer
A non-impact printer forms characters & graphics on a piece of paper without actually
striking the paper.
Some spray ink, while others use heat & pressure to create images. Because, these
printers do not strike the paper, they are much quieter than impact printers.
The commonly used types of the non-impact printers are:
 Ink-jet printers
 Laser Printers
Ink-Jet Printers
Ink Jet Printers create characters & graphics by spraying tiny drops of liquid ink onto
a piece of paper.
Ink Jet Printers usually use individual sheets of paper
stored in removable or stationary tray.
These printers can print both black & white & color prints
on a variety of paper types. e.g., plain papers, photo
paper, glossy paper and banner paper.
Most Ink Jet Printers have the resolution ranges from
300 to 2400 dpi & speed 3 to 20 ppm.
Higher the dpi, better the quality of the image
Ink Jet Printers have become most popular type of the color printers especially in
homes because of their lower cost & better quality printing
Laser Printers
Laser Printers use a laser to mark the parts of the page where the text & image is to
formed. The paper is passed through a toner solution where the mark areas pick up
the toner & the text becomes visible.
Laser Printers usually use individual sheets of paper
stored in removable or stationary tray. Some laser
printers have trays that can accommodate different sizes
of papers.
These Printers can print both black, while & gray and
color prints. However, color laser printers are expensive.
HP Laser Jet 2100
Most Laser Printers have the resolution ranges from 600
to 2400 dpi & speed 6 to 40 ppm.
HP Color Laser Jet 4550
Plotters
Unlike Laser, Ink Jet & Dot Matrix Printers, Plotters have the ability to produce large
scale, high quality perfectly graphic output.
Architects, engineers, graphic artists, city planners,
and others who routinely generate high-precision,
hard copy output of widely varying sizes use
another hard copy alternative called plotters.
Plotters use ink-jet technology to print on roll-feed
paper up to 4 feet wide and 50 feet in length.
Plotters are used in large printing needs such as
commercial posters and blueprints. They can be
used to produce continuous output such as charts
and earthquake activities.
HP Design Jet Series 1050
3.
SYSTEM UNIT
What is System?
 A system can be defined as a combination of
some related components that interact with
each other to perform specific tasks.
System Unit
 The main part computer is a system unit
 System unit is a case that contains all
components which are very important for the
processing of data
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System Unit
The main components of system unit are here
under:
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Mother Board
CPU
Primary Memory
Ports & connectors
Expansion slots & Adaptor
Cards
Buses
Power supply
Mother Board
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it is the primary printed circuit board in a
computer or other electronic device
Main circuit board in system unit
 Contains chips,
 Integrated circuits,
 and transistors
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Also called system board/Main board
The Von Neumann Architecture
Before discussing the CPU, memory and
other system unit components I would like
to
introduce
the
Von
Neumann
Architecture
Von Neumann
Architecture
Designing Computer
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All computers more or less based on the same
basic design, the Von Neumann Architecture
The Von Neumann Architecture
Bus
Processor (CPU)
Input-Output
Memory
Control Unit
ALU
Store data and program
Execute program
Do arithmetic/logic operations
requested by program
Communicate with
"outside world", e.g.
• Screen
• Keyboard
• Storage devices
• ...
Central Processing Unit (CPU)
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It is the part of a computer system that is
commonly referred to as the "brains" of a
computer.
The CPU is also known as the “processor” or
“microprocessor”.
The CPU is responsible for executing a
sequence of stored instructions called a
program.
Parts of CPU
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CPU is subdivided in to three parts defined
below:
Arithmetic and logical Unit
Control Unit
Register
Arithmetic and Logical Unit
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This unit of the CPU is capable of performing
arithmetic and logical operations
The arithmetic unit of ALU performs
arithmetic
operations
like
addition,
multiplication, subtraction and division.
The Logical unit of ALU performs logical
operations such as comparisons less than,
equal to.
Registers
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A processor has its own memory inside it in the
shape of small cells.
Each memory cell is called a "Register".
Registers are used to carry data temporarily for
performing operations.
Processors have many different types of registers,
each with a specific storage function.
Register functions include storing the location from
where an instruction was fetched, storing and
instruction while the control unit decodes it,
storing the data while the ALU computes it, and
storing the results of a calculation
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Control Unit
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This unit of the processor controls all the
activities of the processor
Fetches the instruction and decodes it, and
sends control signals to the other units
It obtains instructions from the program
stored in main memory.
It acts just like a police inspector who
controls the traffic on a road.
Control Unit
The control unit is the part of the CPU that controls the
activities of the rest of the components both within and
outside the CPU.
It interprets each instruction issued by program & then
initiates the appropriate action to carry out the
instruction.
The control unit performs four basic operations for every
instruction:
 Fetching
 Decoding
 Executing
 Storing
Fetching
Fetching is the process of obtaining a program instruction or data item from memory.
Decoding
Decoding refers to the process of translating the instruction into commands the
computer can execute
Control Unit
Executing
Executing is the process of carrying out the commands
Storing
Storing is the process of writing the results to memory (not storage medium)
Together these four operations comprise a machine cycle or instruction cycle
Pipelining
Processors starting from Intel Pentium 3 & 4 support
Pipelining.
In some & obsolete computers, the CPU processes only one
instruction at one time. i.e., the CPU waits until an
instruction completes all four stages of the machine cycle
before beginning work on the next instruction.
With Pipelining, the CPU begins
executing a second instruction
before it completes the first
instruction. Pipelining results
faster processing because the
CPU does not have to wait for
one instruction to complete
Main Memory
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The primary memory or the main memory is
part of the main computer system.
The processor or the CPU directly stores
and retrieves information from it.
Random Access Memory (RAM)
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RAM is used to store programs and data that
are being used by the computer.
When the computer is turned on the RAM is
empty.
The data in RAM is lost when the computer
is turned off so it is known as Volatile
Memory.
RAM is further divided in to two types
 SRAM (Static Random access Memory)
 DRAM (Dynamic Random access Memory)
SRAM
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SRAM stands for Static RAM.
SRAM is a type of memory that is faster and
more reliable than the more common DRAM
(dynamic RAM).
The term static is derived from the fact that it
doesn't need to be refreshed like dynamic
RAM
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Access time around 10 nanoseconds
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Note: a nanosecond is one billionth of a second!
DRAM
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DRAM stands for Dynamic RAM.
The term dynamic indicates that the memory
must be constantly refreshed or it will lose
its contents.
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Contents are constantly refreshed 1000 times per second
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Access time 60 – 70 nanoseconds
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Dynamic RAM is slower than Static RAM.
But it requires less power and is less
expensive.
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SDRAM (Synchronous Dynamic RAM) is much
faster
than
DRAM
because
they
are
synchronized to system clock..
DDR SDRAM (Double Date Rate SDRAM) are
faster than SDRAM because they transfer data
twice the system cycle.
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The processor relies on a small quartz crystal circuit called
the system clock to control the timing of all computer
operations. Just as your heart beats at a regular rate to
keep your body functioning, the system clock generates
regular electronic pulses, or ticks, that set the operating
pace of components of the system unit
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The pace of the system clock, called the clock speed, is measured by the number of ticks per
second. Current personal computer processors have clock speeds in the gigahertz range. Giga is a
prefix that stands for billion, and a hertz is one cycle per second. Thus, one gigahertz (GHz) equals
one billion ticks of the system clock per second
.
Cache
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A cache is a smaller, faster memory which
stores copies of the data from the most
frequently used main memory locations
A cache is a component that transparently
stores data so that future requests for that
data can be served faster.
The data that is stored within a cache might be
values that have been computed earlier or
duplicates of original values that are stored
elsewhere.
• Level
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1 cache is built within the CPU (internal)
Cache that is closest to the processor: typically
located inside the CPU chip. Also referred to as
primary cache or internal cache. often
accessed in just a few cycles, usually tens of
kilobytes
• Level
2 cache may be on chip or nearby
(external)
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Cache that is second closest to the processor;
typically located on the system board. Also
referred to as secondary cache and external
cache.
The operation of cache memory
1. Cache fetches data
from next to current
addresses
in
main
memory
2. CPU checks to see
whether
the
next
instruction it requires is in
cache
Main
Cache
Memory
Memory
(DRAM)
(SRAM)
4. If not, the CPU has to
fetch next instruction
from main memory - a
much slower process
CPU
3. If it is, then the
instruction is fetched from
the cache – a very fast
position
= Bus connections
L2 Cache Structure
Cache Hits
 When the cache contains the information
requested, the transaction is said to be a
cache hit.
Cache Miss
 When
the cache does not contain the
information requested, the transaction is said
to be a cache miss.
Read Only Memory(ROM)
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The contents of ROM are permanent for
example BIOS which is a sequence of
instructions the computer follows to lead the
operating system & other files when you first
turn on the computer.
The content is written onto the ROM when it
is first made.
ROM keeps its contents even when the
computer is turned off and so is known as
Non-Volatile Memory.
Types of ROM
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ROM is further divided in to three types
PROM (Programmable Read-Only Memory)
EPROM (Erasable Programmable Read-Only
Memory)
EEPROM
(Electronically
Erasable
Programmable Read-Only Memory)
PROM
• PROMs are manufactured as blank chips on which data can be
written with a special device called a PROM programmer.
EPROM
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A rewritable memory chip that holds its content without power.
EPROM chips are written on an external programming device
before being placed on the mother board.
EEPROM
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A rewritable memory chip that holds its content without power.
EEPROMs are typically used on circuit boards to store small
amounts of instructions and data.
Ports & Connectors
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A personal computer may have several ports
for connecting devices such as a trackball,
expanded keyboard, flatbed scanner, touch
screen, and other device peripherals.
There are two types of ports
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Serial port (Serial ports can transfer one
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Parallel port (Parallel port can transfer
bit at a time)
more that one bit a time. )
Buses
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In computer architecture, a bus is a
subsystem that transfers data between
components inside a computer, or between
computers
Types of Buses
System bus
Expansion bus
System Bus
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System bus connects processor and RAM. It is
also called internal bus.
it is subdivided in to two types:
Address bus
Data bus
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ADDRESS BUS
The address bus is a unidirectional pathway that
carries
addresses
generated
by
the
microprocessor to the memory.
DATA BUS
In contrast to the address bus, the data bus is bidirectional in nature.
Data flows along the data bus from the
microprocessor to memory during a Write
operation.
Conversely, data moves from memory to the
microprocessor during a Read operation.
Power Supply
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It supply electric supply to all components of
system unit.
It Converts alternating current (AC) to direct
current (DC).