Excess 3 Code

Duration: 8 min

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Module outline

  1. About the course: About the Course
  2. Mathematical Aptitude: संख्या पद्धति / Number System, महत्तम समापवर्तक और लघुत्तम समापवर्त्य / HCF and LCM, Divisibility Rules, प्रतिशत / Percentage, अनुपात और समानुपात / Ratio and Proportion, औसत / Average, लाभ, हानि और बट्टा / Profit, Loss and Discount, समय और कार्य / Time and Work, घन क्षेत्रमिति / Solid Mensuration, साधारण और चक्रवृद्धि ब्याज / Simple and Compound Interest, समय, चाल और दूरी / Time, Speed and Distance, Age Problems, मिश्रण और एलिगेशन / Mixture and Alligation, Algebra, सरलीकरण, घातांक और करणी / Simplification, Indices and Surds, Pipe and Cistern, Trigonometry, Statistics, आँकड़ा निर्वचन / Data Interpretation, Arithmetic, समुच्चय, संबंध, फलन और विविक्त गणित / Sets, Relations, Functions and Discrete Mathematics, संख्या पद्धति और संख्या सिद्धांत / Number Systems and Number Theory, निर्देशांक ज्यामिति, सदिश और त्रिविमीय ज्यामिति / Coordinate Geometry, Vectors and 3D Geometry, बहुपद, समीकरण और सम्मिश्र संख्याएँ / Polynomials, Equations and Complex Numbers
  3. Logical Reasoning: श्रेणी / Series, कूट लेखन एवं कूट वाचन / Coding-Decoding, सादृश्यता एवं वर्गीकरण / Analogy and Classification, रक्त संबंध / Blood Relations, दिशा एवं दूरी / Direction and Distance, क्रम एवं रैंकिंग / Order and Ranking, अशाब्दिक तर्क / Non-Verbal Reasoning, बैठक व्यवस्था एवं पहेलियाँ / Seating Arrangement and Puzzles, Syllogisms, वेन आरेख, न्याय वाक्य एवं असमानता / Venn Diagrams, Syllogism and Inequalities, गणितीय संक्रियाएँ एवं लुप्त संख्या / Mathematical Operations and Missing Numbers, वर्णमाला एवं संख्या परीक्षण / Alphabet and Number Test, कथन आधारित तार्किक विवेचन / Statement-Based Reasoning, Analytical Reasoning (Counting Figures Reasoning), घन, पासा एवं आकृतियों की गिनती / Cubes, Dice and Figure Counting, कैलेंडर एवं घड़ी / Calendar and Clock, Clock
  4. General Knowledge: वैज्ञानिक उपलब्धियाँ और अनुसंधान / Scientific Achievements and Research, Chemistry, Biology, History, Geography, Polity, Indian Economy, समसामयिकी / Current Affairs, Static General Knowledge
  5. Art of Teaching: शिक्षण-अधिगम प्रक्रिया एवं कक्षा प्रबंधन / Teaching-Learning Process and Classroom Management, Learners & Learning Process, Factors Affecting Teaching, शिक्षण विधियाँ एवं उपागम / Teaching Methods and Approaches, सूक्ष्म शिक्षण एवं कक्षा संप्रेषण / Microteaching and Classroom Communication, शिक्षण सहायक सामग्री एवं शैक्षिक तकनीकी / Teaching Aids and Educational Technology, आकलन एवं मूल्यांकन / Assessment and Evaluation, शिक्षक: गुण, व्यावसायिक नैतिकता एवं विकास / Teacher: Qualities, Professional Ethics and Development, शैक्षिक नीतियाँ, अधिनियम एवं प्रशासन / Educational Policies, Acts and Administration, पाठ्यचर्या, कला एवं सह-शैक्षिक क्षेत्र / Curriculum, Arts and Co-curricular Areas, निर्देशन एवं परामर्श / Guidance and Counselling, दिव्यांग बच्चों की शिक्षा / Education of Children with Disabilities, Micro-Teaching & Teaching Skills, पाठ योजना / Lesson Planning
  6. Environmental Science: Environment
  7. Unit 1 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  8. Unit 2 | COA: Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Instr Formats & Modes, Control Unit Design, Register Transfer and Microoperations, Programming the Basic Computer
  9. Unit 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  10. Unit 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  11. Unit 4 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  12. Unit 5 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management
  13. Unit 6 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Transaction Management, Concurrency Control
  14. Unit 7 | Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer
  15. Unit 8 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  16. Unit 9 | Object Oriented Programming: OOPS with C++
  17. Unit 10 | Web Development: HTML Basics, CSS, JavaScript-Basics, XML, Node.js
  18. Unit 11 | Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines
  19. Unit 12 | IoT: Emerging Tech Trends, Cloud Computing, कंप्यूटर नेटवर्क / Computer Networks
  20. Unit 13 | Artificial Intelligence: Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms
  21. Unit 14 | E-Commerce: Electronic Data Interchange and E-Commerce, Role of Internet and Web Services, Security in Mobile and Wireless Computing, Physical Security and Cryptography Basics, Cyber Safety and Security
  22. Unit 15 | Multimedia: Multimedia
  23. Unit 16 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
  24. Full Length Mock Tests — General Paper:
  25. Full Length Mock Tests — Computer Science (Paper II):
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This educational video provides a detailed lecture on Excess-3 code, a specific type of binary-coded decimal (BCD) system. The instructor defines it as a self-complementary, biased representation often abbreviated as XS-3 or Stibitz code. The lesson covers the fundamental encoding method where each decimal digit is converted to its 4-bit binary equivalent and then added to 3 (0011). Through various examples, including single digits and multi-digit numbers like 127, the instructor demonstrates the encoding process. The lecture concludes by exploring the unique properties of Excess-3, specifically its self-complementing nature where the 9's complement is found via bitwise inversion, and the specific arithmetic rules required to correct sums that result in an Excess-6 bias.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with a title slide "Excess-3 Code" and introductory text defining it as a self-complementary binary-coded decimal (BCD) code and numeral system. The instructor highlights the text "XS-3, 3XS or X3" and writes these abbreviations on the screen. He points out that it is a biased representation and mentions its historical use in older computers and 1970s calculators. A table is visible on the right, listing Decimal digits 0 through 9 alongside their Excess-3 binary equivalents, such as 0 mapping to 0011 and 9 mapping to 1100. The instructor begins a practical demonstration by writing "decimal 0" on the board. He converts this to standard BCD "0000" and then adds binary "0011" (which represents decimal 3) to arrive at the final Excess-3 code "0011". This establishes the core rule that Excess-3 is simply BCD plus 3.

  2. 2:00 – 5:00 02:00-05:00

    The instructor continues with further encoding examples to reinforce the concept. He writes "decimal 2" and converts it to BCD "0010". He adds "0011" to this value, resulting in the Excess-3 code "0101". He then moves to a more complex example, the number 127. He breaks the number down into its constituent digits: 1, 2, and 7. For the digit 1, he writes BCD "0001" and adds "0011" to get "0100". For the digit 2, he uses BCD "0010" plus "0011" to get "0101". For the digit 7, he uses BCD "0111" plus "0011" to get "1010". He combines these results to show the full Excess-3 representation of 127 as "0100 0101 1010". During this process, he writes "unweighted" and "self complementing" on the board to describe the code's characteristics. He also notes that Excess-3 arithmetic uses different algorithms than normal BCD.

  3. 5:00 – 8:17 05:00-08:17

    The final segment focuses on the self-complementing property and arithmetic correction. The instructor explains that for self-complementing codes, the 9's complement of a decimal number is obtained directly by changing 1s to 0s and 0s to 1s. He uses the example of the decimal number 395. He writes its Excess-3 representation as "0110 1100 1000". He calculates the 9's complement as 999 - 395 = 604. He then shows that the Excess-3 code for 604 is "1001 0011 0111". By visually comparing the two codes, he demonstrates that the Excess-3 code for 604 is the bitwise complement of the Excess-3 code for 395. Finally, he addresses the arithmetic aspect, stating that after adding two Excess-3 digits, the raw sum is Excess-6. To correct this, it is necessary to remove the extra bias by subtracting binary "0011" (decimal 3 in unbiased binary).

The lecture progresses logically from definition to application to advanced properties. It starts by defining Excess-3 as a biased BCD code and establishing the "BCD + 3" encoding rule. It then applies this rule to single and multi-digit numbers, showing the step-by-step binary addition. Finally, it deepens the understanding by explaining the self-complementing property, proving it with the 395/604 example, and clarifying the specific arithmetic adjustments needed for addition, ensuring students grasp both the theoretical and practical aspects of the code.

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