Von Neumann Architecture

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 devices2.Output Devices3.System Unit

Hardware

Any hardware component used to enter data, programs, commands, and user responses into a computer

• Examples • Key Board• Mouse• Digital Camera• Webcam • Scanner etc

1. Input Devices

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

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

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.

KeyboardKeyboard

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

Pointing Devices

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 thescreen and make selection from the screen.

The top of the mouse has one to four 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.

Wheel Mouse

Optical Mouse

Mouse

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 sensorsand other uses laser.

Mouse Types

Inside the Mechanical & Optical MouseWireless Mouse

WIRELESS MOUSE : battery powered devices that transmit data using wireless technology, such as radio waves or infrared light waves.

Mouse Types

A mechanical mouse has a ball on the bottom, a trackball is a stationarypointing device with a ball on its top.

The trackball can also be inserted in a small external box near the keyboard. The ballis rolled with the finger to move the cursor.

Some people like to think of the trackball as an upside-down mouse with a bigger ballat the bottom.

Trackball

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.

Joystick

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.

Trackpad/Touchpad

A trackpoint or pointing stick is a pressure sensitive pointing device shaped like apencil 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.

Trackpoint/Pointing Stick

A "biometric device" is any device that measures a biological function or trait (genetic characteristics)

Examples Voice recognition Thumb impression Retina scanner Face recognition

Biometric Devices

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 likeNaturally Speaking.

DIGITAL CAMERA

A digital camera allows you to take pictures and store the photographed imagesdigitally, instead of on traditional film.

Digital images stored then can be edited using some Digital Image Processing techniques.

• Any hardware component used to show results after processing to any user. Output can be text, Audio, Video & graphics.

• Examples Display device

• Monitor• Printer• Plotter

• Projectors• Speakers • Headphone etc•  

2. OUTPUT DEVICES

A display device is simply an output device that visually conveys text, graphics & video information.

Information on a display device, sometimescalled soft copy exists for a temporary period only.

Display devices include:

CRT Monitors LCD Monitors Gas Plasma Monitors Televisions

Monitors

Display Devices

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

The actual viewable area is however, less than the diagonal size. For example, a 21 inches monitor will have 19.8 inches viewable area

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.

CRT 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

LCD 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

Gas Plasma Monitors

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 permanentthan a soft copy.

There are two types of printers:

1. Impact Printers2. Non-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

Impact Printers

Two commonly used types of impact printers are:

a. Dot Matrix Printersb. Line Printers

Dot Matrix Printers

Dot Matrix Printer produces the printed images when tiny wire pins on a print headmechanism 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 arecapable to print 3000 LPM.

A line printer is often connected with a midrange mainframe, server or network.

Line printers are bigger in size & are moreexpensive than dot matrix printers.

Printers

A non-impact printer forms characters & graphics on a piece of paper without actuallystriking the paper.

Some spray ink, while others use heat & pressure to create images. Because, theseprinters 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

Non-impact Printer

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 paperstored in removable or stationary tray.

These printers can print both black & white & color printson 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

Ink-Jet 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 paperstored 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.

Most Laser Printers have the resolution ranges from 600 to 2400 dpi & speed 6 to 40 ppm.

HP Laser Jet 2100

HP Color Laser Jet 4550

Laser Printers

Unlike Laser, Ink Jet & Dot Matrix Printers, Plotters have the ability to produce large scale, high quality perfectly graphic output.

HP Design Jet Series 1050

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.

Plotters

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

3. SYSTEM UNIT

The main components of system unit are here under:

• Mother Board• CPU• Primary Memory• Ports & connectors• Expansion slots & Adaptor

Cards• Buses • Power supply

System Unit

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

Also called system board/Main board

Mother Board

Von NeumannVon NeumannArchitectureArchitecture

Before discussing the CPU, memory and other system unit components I would like to introduce the Von Neumann Architecture

The Von Neumann Architecture

All computers more or less based on the same basic design, the Von Neumann Architecture

Von Neumann Architecture!

Designing Computer

Memory

Processor (CPU)

Input-OutputControl Unit

ALUStore data and programStore data and program

Execute programExecute program

Do arithmetic/logic operationsDo arithmetic/logic operationsrequested by programrequested by program

Communicate withCommunicate with"outside world", e.g. "outside world", e.g. • ScreenScreen• KeyboardKeyboard• Storage devices Storage devices • ......

Bus

The Von Neumann Architecture

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.

Central Processing Unit (CPU)

CPU is subdivided in to three parts defined below:

Arithmetic and logical Unit Control Unit Register

Parts of CPU

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.

Arithmetic and Logical Unit

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

. 

Registers

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

FetchingFetching is the process of obtaining a program instruction or data item from memory.DecodingDecoding refers to the process of translating the instruction into commands thecomputer 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

Control Unit

PipeliningProcessors starting from Intel Pentium 3 & 4 support PipeliningIn 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

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.

Main Memory

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)

Random Access Memory (RAM)

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

• Access time around 10 nanoseconds

• Note: a nanosecond is one billionth of a second!

SRAM)

DRAM stands for Dynamic RAM. The term dynamic indicates that the

memory must be constantly refreshed or it will lose its contents.

• Contents are constantly refreshed 1000 times per second

• Access time 60 – 70 nanoseconds

Dynamic RAM is slower than Static RAM. But it requires less power and is less

expensive.

DRAM)

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.

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

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.

• 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.

Cache

• Level 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)

• 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

3. If it is, then the instruction is fetched from the cache – a very fast position

4. If not, the CPU has to fetch next instruction from main memory - a much slower process

Main

Memory

(DRAM)CPU

Cache

Memory

(SRAM)

= 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.

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.

Read Only Memory(ROM)

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)

Types of ROM

• PROM• PROMs are manufactured as blank chips on which

data can be written with a special device called a PROM programmer.

• EPROMA 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• 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.

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 Serial port (Serial ports can transfer one bit

at a time) Parallel port (Parallel port can transfer

more that one bit a time. )

Ports & Connectors

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

Buses

System bus connects processor and RAM. It is also called internal bus.

it is subdivided in to two types: Address bus Data bus

System Bus

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

bi-directional 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.

It supply electric supply to all components of system unit.

It Converts alternating current (AC) to direct current (DC).

Power Supply

Q?