![Case Study Error in Intel's Pentium Microprocessor
Mathematics professor at Lynchburg College, USA, Dr.Thomas Nicely, found a floating point division error in Intel Pentium
microprocessor in the year 1994. He was computing on his Pentium-based computer to find the sum of the reciprocals of prime numbers.
He noticed that the computation result was significantly different from the theoretical values. When the same computation was carried out
on another computer with a different microprocessor (486 CPU) he was able to get the correct values that obey the theoretical values. The
worst and well-known case was division of 4195835 by 3145727. The correct value is 1.33382, however the Pentium's floating point unit
computed and generated a value 1.33374 (Only 6 places after decimal is mentioned here), which has an error of 0.006.
Dr.Thomas Nicely reported the bug to Intel, but Intel ignored it and Nicley did not receive any proper response from Intel. Later, Nicley
took the issue to public with the help of the Internet and media. Following these events, Intel publicly announced that "an error is only
likely to occur [about] once in nine billion random floating points". They also mentioned in their announcement that "an average
spreadsheet user could encounter this subtle flaw once in every 27,000 years of use." However, it was noted that the Intel Pentium
processors output was wrong every time when such division was performed for such values.
On November 28, 1994, Intel publicly admitted the problem and issued a statement saying that it would replace pentium chips only for
those who could explain the need of high accuracy in complex calculations. Industry experts, public, and media criticized this attitude of
Intel. Later, in the month of December, Intel announced that it would freely replace the processor for any owner who asked for one.
The bug problem made Intel to issue an apology to its customers and the public for the way it handled the bug and issues related to it. It
had to spend more than $400 million for replacing bad chips. Learning a lesson from this, Intel now reports all known problems on its
official website and it also monitors customer feedbacks carefully and regularly.
Questions
1. Is Intel right in their approach to customers? How did they win customers’ confidence?
2. Explain the kind of bug faced by Intel. What method would you suggest to overcome the bug?](https://image.slidesharecdn.com/lecture2-240510120340-ae4c1879/85/Software-Development-Lifecycle-Presentation-22-320.jpg)
Software Development Lifecycle Presentation
- 1. Astana IT University Advanced QA PhD Adamova Aigul Dyusenbinovna Aigul.adamova@astanait.edu.kz Software Development Lifecycle Week: 2
- 3. Today’s agenda Software Development Model Software Testing Axioms Software Testing Terms and Definitions
- 4. Software Development Lifecycle (SDLC) Process of producing and maintaining software systems Primary goal is delivering software that is: High quality 1. Meets customer expectations 2. On time & within budget 3. SDLC consist of several phases...
- 5. SDLC Process & Phases Variations in names / phases but follows same process: Requirements 1. Design 2. Implementation 3. Testing 4. Deployment 5. Maintenance 6.
- 6. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design 2. Implementation 3. Testing 4. Deployment 5. Maintenance 6.
- 7. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design: Determine architectural structure documents 2. Implementation 3. Testing 4. Deployment 5. Maintenance 6.
- 8. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design: Determine architectural structure documents 2. Implementation: Product coded & built to spec 3. Testing 4. Deployment 5. Maintenance 6.
- 9. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design: Determine architectural structure documents 2. Implementation: Product coded & built to spec 3. Testing: Fix bugs, errors & inconsistencies 4. Deployment 5. Maintenance 6.
- 10. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design: Determine architectural structure documents 2. Implementation: Product coded & built to spec 3. Testing: Fix bugs, errors & inconsistencies 4. Deployment: Public release, inc. training & help files 5. Maintenance 6.
- 11. SDLC Process & Phases Variations in names / phases but follows same process: Requirements: Gather & define project foundation 1. Design: Determine architectural structure documents 2. Implementation: Product coded & built to spec 3. Testing: Fix bugs, errors & inconsistencies 4. Deployment: Public release, inc. training & help files 5. Maintenance: Support, big fixes, updates etc. 6.
- 12. Role of Testing in SDLC Testing is an essential part of the SDLC Ensures quality and reliability Occurs throughout development process Identify & fix defects early Prevents mistakes, reduces risk of failure
- 13. Testing in different SDLC Phases Requirements - validate & verify that clear & complete 1. Design - check documents are accurate & consistent 2. Implementation - develop test cases, run Unit Testing 3. Testing - execute cases, identify defects & retest 4. Deployment - verify correct, provide support material 5. Maintenance - test new features, bug fixes and changes 6.
- 15. SDLC Quiz Activities Requirements Elicitation Analysis Specification ??? Prioritisation Design Architectural design Detailed design Interface design Design documentation Implementation Coding Code review (e.g., peer code review) Integration Code refactoring Testing Test planning Test case design Test evaluation Defect tracking Deployment Configuration management Release management Deployment Maintenance ??? ??? ??? ??? Unit testing Post-deployment validation Validation Design review Test execution
- 16. Waterfall model Software Development Model V model Spiral model RAD model Agile model
- 17. Waterfall model Software Development Model
- 18. Spiral model Software Development Model
- 19. V model Software Development Model
- 20. RAD model Software Development Model
- 21. Agile model Software Development Model
- 22. Case Study Error in Intel's Pentium Microprocessor Mathematics professor at Lynchburg College, USA, Dr.Thomas Nicely, found a floating point division error in Intel Pentium microprocessor in the year 1994. He was computing on his Pentium-based computer to find the sum of the reciprocals of prime numbers. He noticed that the computation result was significantly different from the theoretical values. When the same computation was carried out on another computer with a different microprocessor (486 CPU) he was able to get the correct values that obey the theoretical values. The worst and well-known case was division of 4195835 by 3145727. The correct value is 1.33382, however the Pentium's floating point unit computed and generated a value 1.33374 (Only 6 places after decimal is mentioned here), which has an error of 0.006. Dr.Thomas Nicely reported the bug to Intel, but Intel ignored it and Nicley did not receive any proper response from Intel. Later, Nicley took the issue to public with the help of the Internet and media. Following these events, Intel publicly announced that "an error is only likely to occur [about] once in nine billion random floating points". They also mentioned in their announcement that "an average spreadsheet user could encounter this subtle flaw once in every 27,000 years of use." However, it was noted that the Intel Pentium processors output was wrong every time when such division was performed for such values. On November 28, 1994, Intel publicly admitted the problem and issued a statement saying that it would replace pentium chips only for those who could explain the need of high accuracy in complex calculations. Industry experts, public, and media criticized this attitude of Intel. Later, in the month of December, Intel announced that it would freely replace the processor for any owner who asked for one. The bug problem made Intel to issue an apology to its customers and the public for the way it handled the bug and issues related to it. It had to spend more than $400 million for replacing bad chips. Learning a lesson from this, Intel now reports all known problems on its official website and it also monitors customer feedbacks carefully and regularly. Questions 1. Is Intel right in their approach to customers? How did they win customers’ confidence? 2. Explain the kind of bug faced by Intel. What method would you suggest to overcome the bug?
- 24. Axiom 1 It is impossible to test a program completely Software Testing Axioms Axiom 2 Software testing is a risk- based exercise Axiom 3 Testing cannot show the absence of bugs. Axiom 4 The more bugs you find, the more bugs there are. Axiom 5 Not all bugs found will be fixed. Axiom 6 It is difficult to say when a bug is indeed a bug. Axiom 7 Specifications are never final. Axiom 8 Software testers are not the most popular members of a project. Axiom 9 Software testing is a disciplined and technical profession.
- 25. Software Quality Software Testing Terms and Definitions Verification Validation Quality Assurance Quality Control Test plan Test case is impacted by bugs. It is essential that the software is bug free or defect free and meets the requirements, specifications, and expectations of the client. the process of discovering the possible failures in the software before the commencement of the testing phase. It involves reviews, inspections, meetings, code reviews, and specifications. It answers the question.” Are we building the product right?” the actual testing of the product happens at a later stage. Defects which occur due to discrepancies in functionality and specifications are detected in this phase. It answers the question, “Are we building the right product?”
- 26. Software Quality Software Testing Terms and Definitions Verification Validation Quality Assurance Quality Control Test plan Test case is a document which gives information about the objectives, scope, approach and the various attributes that the testing project must focus on. The main aim is to evaluate whether the deliverables are of acceptable quality. The focus thus is to detect defects and correction of these defects (correction oriented). The activities ensure data integrity, correctness and completeness. The activities are more generic and can encompass the whole development process. The main aim is to prevent defects, and thus it focuses on the process of product or application building. is a document and is the smallest unit of testing. It has a developed set of inputs, execution preconditions and expected outcomes for a specific objective.
- 28. Questions 1. Is there any difference between the water fall model and the spiral model? Discuss. 2. In V model, test cases are developed at every stage of software development. Explain. 3. Explain how you will carry out software development process using RAD model. 4. In Agile model, the customers, developers, and testers constantly interact with each other during the entire development process. Discuss. 5. How does test strategy differ from the test technique? Substantiate how planning a strategy helps in efficient testing. 6. Suppose you are recruited as a tester in a software company, what qualities are you expected to exhibit? 7. Do you think software testers need to be just knowledgeable in their domain? Are there any specific soft skills they are expected to exhibit? 8. “The process of static test is very tedious”. Explain why. 9. Is there any difference between Verification and Validation? Discuss 10. “Not all bugs found will be fixed. “ How would you substantiate this axiom?
- 29. Summary Testing plays critical role in SDLC Ensures software is reliable & defect-tree Testing throughout the SDLC minimises risk of software failure The Waterfall model of software development is a traditional model which follows sequential method of software development. V and Spiral models, which employ testing as an integral part of software development, are more efficient than the Waterfall model. Agile is considered to be the most advanced and efficient type of software development model. Extreme Programming (XP) is a method developed based on the agile model, which uses test driven development to develop highly efficient software.