IT Department Final Year - B.TECH / B.E - 2008 Regulation - Anna University Chennai

C# .Net (CONSOLE APPLIACTION) Online Shopping using 5 compoment (project) - SOA Lab - IT Department - Final Year

ONLINE SHOPPING PROGRAM USING C#

DOWNLOAD AS TEXT FILE

DOWNLOAD AS WORD FILE

DOWNLOAD C# PROJECT FILE


program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using computer;
using com_det;
using invoice;
using orderclass;
using customer;

namespace Exp1
{
    class Program
    {
        static void Main(string[] args)
        {
            //string i;
            int h;

            Console.WriteLine(" Online Shopping ");
            Console.WriteLine(" Computer Sales !!!! ");
            Console.WriteLine(" 1. View Catalogue ");
            Console.WriteLine(" 2. Exit ");
            Console.WriteLine(" Enter your choice ");

            h = Convert.ToInt32(Console.ReadLine());

            switch (h)
            {
                case 1:
                    {

                    ara:

                        com ob1 = new com();
                        ob1.display();

                        co_det ob2=new co_det();
                        ob2.display();

                        cus ob3 = new cus();
                        ob3.display();

                        Console.WriteLine(" Do you want to view catalog (Y/N)");
                        string ch;
                        ch = Console.ReadLine();
                        if (ch == "y" || ch == "Y")
                        {
                            goto ara;
                        }

                        else
                        {

                            corder ob4 = new corder();
                            ob4.display();

                            inv ob5 = new inv();
                            ob5.display();

                        }

                        break;
                        
                    }
                   

                default:
                    {
                        Console.WriteLine(" INVALID SELECTION ");
                        Console.ReadLine();
                    }
                    break;


            }

        }
    }
}



computer.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace computer
{
    public class com
    {
        int a;

        public void display()
        {
            Console.WriteLine(" COMPUTERS BRAND ");
            Console.WriteLine(" 1. Sony ");
            Console.WriteLine(" 2. Dell ");
            Console.WriteLine(" 3. HCL ");
            Console.WriteLine(" 4. Samsung ");
        }
    }
}



com_det.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace com_det
{
    class co_det
    {
        int d;

        public void display()
        {
            Console.WriteLine(" SELECT YOUR DESIRED COMPUTER ");
            d = Convert.ToInt32(Console.ReadLine());


            switch (d)
            {
                case 1:
                    {
                        Console.WriteLine(" You have Selected SONY ");
                        Console.WriteLine(" Model - SV101");
                        Console.WriteLine(" ITEM ID : 001");
                        Console.WriteLine(" Price  : Rs. 27,550 only /- ");
                        break;
                    }

                case 2:
                    {
                        Console.WriteLine(" You have Selected DELL ");
                        Console.WriteLine(" Model - Inspiron ");
                        Console.WriteLine(" ITEM ID : 002");
                        Console.WriteLine(" Price  : Rs. 29,550 only /- ");
                        break;
                    }

                case 3:
                    {
                        Console.WriteLine(" You have Selected HCL ");
                        Console.WriteLine(" Model - ME ");
                        Console.WriteLine(" ITEM ID : 003");
                        Console.WriteLine(" Price  : Rs. 25,550 only /- ");
                        break;
                    }


                case 4:
                    {
                        Console.WriteLine(" You have Selected SAMSUNG ");
                        Console.WriteLine(" Model - ChromeBook ");
                        Console.WriteLine(" ITEM ID : 004");
                        Console.WriteLine(" Price  : Rs. 15,550 only /- ");
                        break;
                    }

                default:
                    Console.WriteLine(" Invalid Selection");
                    break;


            }
        }

    }

}




customer.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace customer
{
    public class cus
    {
        string name;
        string add;
        string phno;
        string email;

        public void display()
        {
            int q;
            Console.WriteLine(" Do you want to Continue ...! ");
            Console.WriteLine(" Fill the customer form ");
            Console.WriteLine();
            Console.WriteLine(" 1. YES ");
            Console.WriteLine(" 2. NO ");

            q = Convert.ToInt32(Console.ReadLine());


            switch (q)
            {
                case 1:
                    {
                        Console.WriteLine(" Enter your name : ");
                        name=Console.ReadLine();

                        Console.WriteLine(" Enter your address : ");
                        add=Console.ReadLine();

                        Console.WriteLine(" Enter your Phone Number : ");
                        phno=Console.ReadLine();


                        Console.WriteLine(" CONFIRM YOUR SHIPPING DETAILS ");
                        Console.WriteLine(" Name    : "+name);
                        Console.WriteLine(" Address : "+add);
                        Console.WriteLine(" Phone   : "+phno);
                        Console.ReadLine();

                        break;
                    }

            }


        }

    }
}


invoice.cs


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace invoice
{
    class inv
    {

        public void display()
        {
            Console.WriteLine(" Your Product will be delivered on : "+DateTime.Now.Date.AddDays(2).ToString("dd-MM-yyyy"));
            Console.ReadLine();
        }


    }
}



orderclass.cs



using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace orderclass
{
    public class corder
    {

        int s;

        public void display()
        {
            Console.WriteLine(" Select your payment method ");
            Console.WriteLine(" 1. CHEQUE");
            Console.WriteLine(" 2. CASH ");

            s = Convert.ToInt32(Console.ReadLine());



            switch (s)
            {
                case 1:
                    {
                        Console.WriteLine(" Enter your account number : ");
                        Console.ReadLine();
                        Console.WriteLine(" Name of the bank : ");
                        Console.ReadLine();
                        Console.WriteLine();
                        Console.WriteLine(" Your Order is Confirmed ");

                    }
                    break;


                case 2:

                    Console.WriteLine(" Your orderis confirmed ");
                    break;



           
           
            }
        }
    }
}

OUTPUT:

IT2032 SOFTWARE TESTING VII Semester - Final Year - IT Department (ELECTIVE)

IT2032 SOFTWARE TESTING   (ELECTIVE)

UNIT I INTRODUCTION

Testing as an Engineering Activity – Role of Process in Software Quality – Testing as a

Process – Basic Definitions – Software Testing Principles – The Tester’s Role in a

Software Development Organization – Origins of Defects – Defect Classes – The Defect

Repository and Test Design – Defect Examples – Developer/Tester Support for

Developing a Defect Repository.

UNIT II TEST CASE DESIGN

Introduction to Testing Design Strategies – The Smarter Tester – Test Case Design

Strategies – Using Black Box Approach to Test Case Design Random Testing –

Requirements based testing – positive and negative testing -–– Boundary Value

Analysis – decision tables - Equivalence Class Partitioning state-based testing– causeeffect

graphing – error guessing - compatibility testing – user documentation testing –

domain testing Using White–Box Approach to Test design – Test Adequacy Criteria –

static testing vs. structural testing – code functional testing - Coverage and Control Flow

Graphs – Covering Code Logic – Paths – Their Role in White–box Based Test Design –

code complexity testing – Evaluating Test Adequacy Criteria.

UNIT III LEVELS OF TESTING

The Need for Levels of Testing – Unit Test – Unit Test Planning –Designing the Unit

Tests. The Test Harness – Running the Unit tests and Recording results – Integration

tests – Designing Integration Tests – Integration Test Planning – scenario testing –

defect bash elimination -System Testing – types of system testing - Acceptance testing –

performance testing - Regression Testing – internationalization testing – ad-hoc testing -

Alpha – Beta Tests – testing OO systems – usability and accessibility testing

UNIT IV TEST MANAGEMENT

People and organizational issues in testing – organization structures for testing teams –

testing services - Test Planning – Test Plan Components – Test Plan Attachments –

Locating Test Items – test management – test process - Reporting Test Results – The

role of three groups in Test Planning and Policy Development – Introducing the test

specialist – Skills needed by a test specialist – Building a Testing Group.

UNIT V CONTROLLING AND MONITORING

Software test automation – skills needed for automation – scope of automation – design

and architecture for automation – requirements for a test tool – challenges in automation

- Test metrics and measurements –project, progress and productivity metrics – Status

Meetings – Reports and Control Issues – Criteria for Test Completion – SCM – Types of

reviews – Developing a review program – Components of Review Plans– Reporting

Review Results. – evaluating software quality – defect prevention – testing maturity

model

 TOTAL : 45 PERIODS

TEXT BOOKS:

1. IIene Burnstein “Practical Software Testing” Springer International Edition Chennai,

2003

2. Srinivasan Desikan and Gopalaswamy Ramesh, “ Software Testing – Principles and

Practices”, Pearson education, 2006.. 3. Aditya P.Mathur, “Foundations of Software Testing”, Pearson Education,2008.

IT2042 INFORMATION SECURITY - VII Semester - Final Year - IT Department (ELECTIVE)

IT2042 INFORMATION SECURITY (ELECTIVE)

UNIT I INTRODUCTION

History, what is Information Security, Critical Characteristics of Information, NSTISSC

Security Model, Components of an Information System, Securing the Components,

Balancing Security and Access, The SDLC, The Security SDLC

UNIT II SECURITY INVESTIGATION

Need for Security, Business Needs, Threats, Attacks, Legal, Ethical and Professional

Issues

UNIT III SECURITY ANALYSIS

Risk Management : Identifying and Assessing Risk, Assessing and Controlling Risk

UNIT IV LOGICAL DESIGN

Blueprint for Security, Information Security Poicy, Standards and Practices, ISO

17799/BS 7799, NIST Models, VISA International Security Model, Design of Security

Architecture, Planning for Continuity

UNIT V PHYSICAL DESIGN

Security Technology, IDS, Scanning and Analysis Tools, Cryptography, Access Control

Devices, Physical Security, Security and Personnel

TOTAL : 45 PERIODS

TEXT BOOK:

1. Michael E Whitman and Herbert J Mattord, “Principles of Information Security”, Vikas

Publishing House, New Delhi, 2003

76

REFERENCES:

1. Micki Krause, Harold F. Tipton, “ Handbook of Information Security Management”,

Vol 1-3 CRC Press LLC, 2004.

2. Stuart Mc Clure, Joel Scrambray, George Kurtz, “Hacking Exposed”, Tata McGraw-

Hill, 2003

3. Matt Bishop, “ Computer Security Art and Science”, Pearson/PHI, 2002.

IT2403 SOFTWARE PROJECT MANAGEMENT - VII Semester - Final Year - IT Department

IT2403 SOFTWARE PROJECT MANAGEMENT

UNIT I INTRODUCTION TO SOFTWARE PROJECT MANAGEMENT

Project Definition – Contract Management – Activities Covered By Software Project

Management – Overview Of Project Planning – Stepwise Project Planning.

UNIT II PROJECT EVALUATION

Strategic Assessment – Technical Assessment – Cost Benefit Analysis –Cash Flow

Forecasting – Cost Benefit Evaluation Techniques – Risk Evaluation.

UNIT III ACTIVITY PLANNING

Objectives – Project Schedule – Sequencing and Scheduling Activities –Network

Planning Models – Forward Pass – Backward Pass – Activity Float – Shortening Project

Duration – Activity on Arrow Networks – Risk Management – Nature Of Risk – Types Of

Risk – Managing Risk – Hazard Identification – Hazard Analysis – Risk Planning And

Control.

UNIT IV MONITORING AND CONTROL

Creating Framework – Collecting The Data – Visualizing Progress – Cost Monitoring –

Earned Value – Priortizing Monitoring – Getting Project Back To Target – Change

Control – Managing Contracts – Introduction – Types Of Contract – Stages In Contract

Placement – Typical Terms Of A Contract – Contract Management – Acceptance.

UNIT V MANAGING PEOPLE AND ORGANIZING TEAMS

Introduction – Understanding Behavior – Organizational Behaviour: A Background –

Selecting The Right Person For The Job – Instruction In The Best Methods – Motivation

– The Oldman – Hackman Job Characteristics Model – Working In Groups – Becoming

A Team –Decision Making – Leadership – Organizational Structures – Stress –Health

And Safety – Case Studies.

TOTAL: 45PERIODS

TEXT BOOK

1. Bob Hughes, Mikecotterell, “Software Project Management”, Third Edition, Tata

McGraw Hill, 2004.

REFERENCES

1. Ramesh, Gopalaswamy, "Managing Global Projects", Tata McGraw Hill, 2001.

2. Royce, “Software Project Management”, Pearson Education, 1999.

3. Jalote, “Software Project Management in Practice”, Pearson Education, 2002.

CS2401 COMPUTER GRAPHICS Syllabus - VII Semester - Final Year - IT Department

CS2401 COMPUTER GRAPHICS

UNIT I 2D PRIMITIVES

Output primitives – Line, Circle and Ellipse drawing algorithms - Attributes of output

primitives – Two dimensional Geometric transformation - Two dimensional viewing –

Line, Polygon, Curve and Text clipping algorithms

UNIT II 3D CONCEPTS

Parallel and Perspective projections - Three dimensional object representation –

Polygons, Curved lines, Splines, Quadric Surfaces,- Visualization of data sets - 3D

transformations – Viewing -Visible surface identification.

UNIT III GRAPHICS PROGRAMMING

Color Models – RGB, YIQ, CMY, HSV – Animations – General Computer Animation,

Raster, Keyframe - Graphics programming using OPENGL – Basic graphics primitives –

Drawing three dimensional objects - Drawing three dimensional scenes

UNIT IV RENDERING

Introduction to Shading models – Flat and Smooth shading – Adding texture to faces –

Adding shadows of objects – Building a camera in a program – Creating shaded objects

– Rendering texture – Drawing Shadows.

UNIT V FRACTALS

Fractals and Self similarity – Peano curves – Creating image by iterated functions –

Mandelbrot sets – Julia Sets – Random Fractals – Overview of Ray Tracing –

Intersecting rays with other primitives – Adding Surface texture – Reflections and

Transparency – Boolean operations on Objects.

TOTAL :45PERIODS

TEXT BOOKS:

1. Donald Hearn, Pauline Baker, Computer Graphics – C Version, second edition,

Pearson Education,2004.

2. F.S. Hill, Computer Graphics using OPENGL, Second edition, Pearson

Education,200UNIT III

REFERENCES:

1. James D. Foley, Andries Van Dam, Steven K. Feiner, John F. Hughes, Computer

Graphics- Principles and practice, Second Edition in C, Pearson Education, 2007.

IT2402 Mobile Communication Syllabus - VII Semester - Final Year - IT Department

IT2402 MOBILE COMMUNICATION

UNIT I WIRELESS COMMUNICATION                                                      7

Cellular systems- Frequency Management and Channel Assignment- types of handoff

and their characteristics, dropped call rates & their evaluation -MAC – SDMA – FDMA –

TDMA – CDMA – Cellular Wireless Networks

UNIT II WIRELESS NETWORKS                                                                9

Wireless LAN – IEEE 802.11 Standards – Architecture – Services – Mobile Ad hoc

Networks- WiFi and WiMAX - Wireless Local Loop

UNIT III MOBILE COMMUNICATION SYSTEMS                                      11

GSM-architecture-Location tracking and call setup- Mobility management- Handover-

Security-GSM SMS –International roaming for GSM- call recording functions-subscriber

and service data mgt –-Mobile Number portability -VoIP service for Mobile Networks –

GPRS –Architecture-GPRS procedures-attach and detach procedures-PDP context

procedure-combined RA/LA update procedures-Billing

UNIT IV MOBILE NETWORK AND TRANSPORT LAYERS                    9

Mobile IP – Dynamic Host Configuration Protocol-Mobile Ad Hoc Routing Protocols–

Multicast routing-TCP over Wireless Networks – Indirect TCP – Snooping TCP – Mobile

TCP – Fast Retransmit / Fast Recovery – Transmission/Timeout Freezing-Selective

Retransmission – Transaction Oriented TCP- TCP over 2.5 / 3G wireless Networks

UNIT V APPLICATION LAYER                                                                   9

WAP Model- Mobile Location based services -WAP Gateway –WAP protocols – WAP

user agent profile- caching model-wireless bearers for WAP - WML – WMLScripts - WTA

- iMode- SyncML

TOTAL :45PERIODS

TEXT BOOKS: 1. Jochen Schiller, “Mobile Communications”, Second Edition, Pearson Education,

200UNIT III

2. William Stallings, “Wireless Communications and Networks”, Pearson Education,

2002.

REFERENCES:

1. Kaveh Pahlavan, Prasanth Krishnamoorthy, “Principles of Wireless Networks”, First

Edition, Pearson Education, 200UNIT III

2. Uwe Hansmann, Lothar Merk, Martin S. Nicklons and Thomas Stober, “Principles of

Mobile Computing”, Springer, 200UNIT III

3. C.K.Toh, “AdHoc Mobile Wireless Networks”, First Edition, Pearson Education, 2002.

IT2401 Service Oriented Architecture Syllabus - VII Semester - Final Year - IT Department

IT2401 SERVICE ORIENTED ARCHITECTURE

UNIT I

Roots of SOA – Characteristics of SOA - Comparing SOA to client-server and distributed

internet architectures – Anatomy of SOA- How components in an SOA interrelate -

Principles of service orientation

UNIT II

Web services – Service descriptions – Messaging with SOAP –Message exchange

Patterns – Coordination –Atomic Transactions – Business activities – Orchestration –

Choreography - Service layer abstraction – Application Service Layer – Business

Service Layer – Orchestration Service Layer

UNIT III

Service oriented analysis – Business-centric SOA – Deriving business services- service

modeling - Service Oriented Design – WSDL basics – SOAP basics – SOA composition

guidelines – Entity-centric business service design – Application service design – Taskcentric

business service design

UNIT IV

SOA platform basics – SOA support in J2EE – Java API for XML-based web services

(JAX-WS) - Java architecture for XML binding (JAXB) – Java API for XML Registries

(JAXR) - Java API for XML based RPC (JAX-RPC)- Web Services Interoperability

Technologies (WSIT) - SOA support in .NET – Common Language Runtime - ASP.NET

web forms – ASP.NET web services – Web Services Enhancements (WSE)

UNIT V

WS-BPEL basics – WS-Coordination overview - WS-Choreography, WS-Policy, WSSecurity

TOTAL : 45 PERIODS

TEXT BOOKS:

1. Thomas Erl, “Service-Oriented Architecture: Concepts, Technology, and Design”,

Pearson Education, 2005.

REFERENCES:

1. Thomas Erl, “SOA Principles of Service Design “(The Prentice Hall Service-Oriented

Computing Series from Thomas Erl), 2005.

2. Newcomer, Lomow, “Understanding SOA with Web Services”, Pearson Education,

2005.

3. Sandeep Chatterjee, James Webber, “Developing Enterprise Web Services, An

Architect’s Guide”, Pearson Education, 2005.

4. Dan Woods and Thomas Mattern, “Enterprise SOA Designing IT for Business

Innovation” O’REILLY, First Edition, 2006

IT2351 Network Programming and Management Excepted Question May/June 2013

Network Programming and Management IT2351
UNIT I-V 


1. Explain select and Poll Function in detail.
2. Explain in detail about TCPIIP protocols for lnternetworking and Management
3. Create a TCP socket for acting as a multiple server and echoing the information from the client.
4. write notes on Iterative Server and Concurrent Server Operation
5. Describe about the different socket option for internet operation and control
6. Discuss lPv6 support in DNS
7. Explain the purpose and usage of UDP socket and their different functions.
8. Explain DNS in Detail
9. Explain Trace route program with sample code and example
ao.Explain how a TCP echo server using threads is created and also give their advantages
ii. Elaborate about raw socket creation, input and output
12.Write a Short note on mutexes and Condition variables
13. Explain the syntax of the various SNMPvi. message format
14. Explain lpv4 and lpv6 interoperability in details
15. Explain Network monitoring in detail.
16.Explain the architecture of SNMPv3 with neat diagram
17. Compare SNMPv2 And SNMPv3.
i8.Explain the architecture of SNMP entity and traditional SNMP manager as specified in
RFC2 271
19.What is meant by trap-directed polling? Discuss

IT2353 Web Technology - Expected Question For Anna University Exam | Unit Wise | Important Question

IT2353 Web Technology
Important Unit
UNIT WISE



Unit 1

1. Describe IP?
2. Explain any 4 HTML Element.
3. Explain List, Table,  Frame, Form Element.
4. Different between HTML & XHTML
5. HTTP  request and HTTP response.
6. Web Server
7. URL


UNIT 2

1. Explain all Selector Strings.
2. CSS
3. What is Statement in JavaScript? Explain.
4. Explain Functions in JavaScript.
5. Explain JavaScript Array.
6. JavaScript Debugging.
7. Local and Global Functions.


UNIT 3

1. Document Tree.
2. DOM Event Handling.
3. Explain about SERVLET.
4. Explain Session.
5. Dynamic content generation by servlet.
6. Explain how java Servlet performs handling.


UNIT 4

1. XML Syntax and Rules.
2. How XML document displayed in browser.
3. Information in JSP Document.
4. Xpath Node.
5. AJAX Object.
6. JavaBeans Component.
7. XML namespace.
8. XML path language.
9. MVC Architecture.


UNIT 5

1. XML Schema
2. JDBC database Access.
3. SOAP.
4. WSDL
5. Creation of Java Web Server


THANKS :)

NOTES FOR THE 6th SEMESTER .......... INFORMATION TECHNOLOGY DEPT

NOTES FOR THE 6th SEMESTER .......... INFORMATION TECHNOLOGY DEPT

pls click the link below to download the notes.........

https://docs.google.com/file/d/0B1MEIl-F-DIQbncyM3VmekplTDA/edit?usp=sharing

BITSA wishes all its subscribers all success for the exams!!!!!!!!

further notes to be updated soon.........

IT2354 - Embedded System notes - "INTERRUPT"

DOWNLOAD AS WORD FILE

Interrupts

Basics

Busy-wait I/O is extremely inefficient—the CPU does nothing but test the device status

while the I/O transaction is in progress. In many cases, the CPU could do useful work in

parallel with the I/O transaction, such as:

ü

computation, as in determining the next output to send to the device or processing

the last input received, and

ü

control of other I/O devices. To allow parallelism,we need to introduce

new

The interrupt mechanism allows devices to signal the CPU and to force execution of a

particular piece of code. When an interrupt occurs, the program counter’s value is changed

to point to an interrupt handler routine (also commonly known as a device driver) that

takes care of the device: writing the next data, reading data that have just become ready,

and so on. The interrupt mechanism of course saves the value of the PC at the interruption

so that the CPU can return to the program that was interrupted. Interrupts therefore allow

the flow of control in the CPU to change easily between different contexts, such as a

foreground computation and multiple I/O devices. As shown in Figure, the interface

between the CPU and I/O device includes the following signals for interrupting:

ü the I/O device asserts the interrupt request signal when it wants service from the

CPU; and

ü the CPU asserts the interrupt acknowledge signal when it is ready to handle the I/O

device’s request.

The I/O device’s logic decides when to interrupt; for example, it may generate an

interrupt when its status register goes into the ready state. The CPU may not be able to

immediately service an interrupt request because it may be doing something else that must

be finished first—for example, a program that talks to both a high-speed disk drive and

a low-speed keyboard should be designed to finish a disk transaction before handling a

keyboard interrupt. Only when the CPU decides to acknowledge the interrupt does the

CPU change the program counter to point to the device’s handler. The interrupt handler

operates much like a subroutine, except that it is not called by the executing program.

The program that runs when no interrupt is being handled is often called the foreground

program; when the interrupt handler finishes, it returns to the foreground program,

wherever processing was interrupted.

The interrupt mechanism.

Ø Priorities and Vectors

Providing a practical interrupt system requires having more than a simple interrupt

request line. Most systems have more than one I/O device, so there must be some mechanism

for allowing multiple devices to interrupt.We also want to have flexibility in the locations of the

interrupt handling routines,the addresses for devices,and so on. There are two ways in which

interrupts can be generalized to handle multiple devices and to provide more flexible definitions

for the associated hardware and software:

ü interrupt priorities allow the CPU to recognize some interrupts as more important

than others, and

ü interrupt vectors allow the interrupting device to specify its handler.

Prioritized interrupts not only allow multiple devices to be connected to the interrupt

line but also allow the CPU to ignore less important interrupt requests while it handles more

important requests. As shown in Figure, the CPU provides several different interrupt request

signals, shown here as L1, L2, up to Ln. Typically, the lower-numbered interrupt lines are given

higher priority, so in this case, if devices 1, 2,and n all requested interrupts simultaneously, 1’s

request would be acknowledged because it is connected to the highest-priority interrupt line.

Rather than provide a separate interrupt acknowledge line for each device, most CPUs

use a set of signals that provide the priority number of the winning interrupt in binary form (so

that interrupt level 7 requires 3 bits rather than 7). A device knows that its interrupt request was

accepted by seeing its own priority number on the interrupt acknowledge lines.

Prioritized device interrupts.

How do we change the priority of a device?

Simply by connecting it to a different interrupt request line. This requires hardware

modification, so if priorities need to be changeable, removable cards, programmable switches, or

some other mechanism should be provided to make the change easy.

The priority mechanism must ensure that a lower-priority interrupt does not occur when

a higher-priority interrupt is being handled. The decision process is known as masking. When

an interrupt is acknowledged, the CPU stores in an internal register the priority level of that

interrupt. When a subsequent interrupt is received, its priority is checked against the priority

register; the new request is acknowledged only if it has higher priority than the currently pending

interrupt.

When the interrupt handler exits, the priority register must be reset. The need to reset the

priority register is one reason why most architectures introduce a specialized instruction to return

from interrupts rather than using the standard subroutine return instruction. The highest-priority

interrupt is normally called the non maskable interrupt (NMI).The NMI cannot be turned off

and is usually reserved for interrupts caused by power failures—a simple circuit can be used

to detect a dangerously low power supply, and the NMI interrupt handler can be used to save

critical state in nonvolatile memory, turn off I/O devices to eliminate spurious device operation

during power down, and so on.

Most CPUs provide a relatively small number of interrupt priority levels, such as eight.

While more priority levels can be added with external logic, they may not be necessary in all

cases. When several devices naturally assume the same priority (such as when you have several

identical keypads attached to a single CPU), you can combine polling with prioritized interrupts

to efficiently handle the devices.

Using polling to share an interrupt over several devices.

Vectors provide flexibility in a different dimension, namely, the ability to define the

interrupt handler that should service a request from a device. Figure shows the hardware

structure required to support interrupt vectors. In addition to the interrupt request and

acknowledge lines, additional interrupt vector lines run from the devices to the CPU. After a

device’s request is acknowledged, it sends its interrupt vector over those lines to the CPU. The

CPU then uses the vector number as an index in a table stored in memory as shown in Figure.

The location referenced in the interrupt vector table by the vector number gives the address of

the handler.

There are two important things to notice about the interrupt vector mechanism.

First, the device, not the CPU, stores its vector number. In this way, a device can be given

a new handler simply by changing the vector number it sends, without modifying the system

software. For example, vector numbers can be changed by programmable switches.

The second thing to notice is that there is no fixed relationship between vector numbers

and interrupt handlers. The interrupt vector table allows arbitrary relationships between devices

and handlers. The vector mechanism provides great flexibility in the coupling of hardware

devices and the software routines that service them.

Most modern CPUs implement both prioritized and vectored interrupts. Priorities

determine which device is serviced first, and vectors determine what routine is used to service

the interrupt. The combination of the two provides a rich interface between hardware and

software.