Excess 3 Code

Duration: 8 min

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  1. About the Course: About the Course
  2. Section 1 | Language (Hindi): भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  3. Section 1 | Language (उर्दू भाषा — 22 प्रश्न (निश्चित)): Spelling & Diacritics, Grammar (اسم, فعل, صفت, ضمیر), Vocabulary, Idioms & Proverbs, Comprehension
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  6. Section 2 | Primary Maths & Reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Mensuration and Geometry, Age Problems, Arithmetic, Powers and Exponents (Surds and Indices), Algebra, Probability, Trigonometry, Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence
  7. Section 2 | General Awareness (GK + Current Affairs): Polity, Physics, Biology, State Wise GK, Chemistry, History, Geography, Indian Economy, Environment, GK- Current Affairs, Static General Knowledge
  8. Section 3 | Computer System and Org. (CSO): Basics of COA, Floating Point Rep, Cache Memory Organization, Instr Formats & Modes, Programming the Basic Computer, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design
  9. Section 3 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, SQL, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control
  10. Section 3 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Process Synchronization
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  12. Section 3 | Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Shortest Path Algos
  13. Section 3 | Theory Of Computation & Compiler Design: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization
  14. Section 3 | Emerging Trends (AI, Societal Ethics & MS Office): Artificial Intelligence, Emerging Tech Trends, Society, Law & Ethics, MS Office Applications
  15. Section 3 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Maintenance and Configuration Management, Software Testing
  16. Section 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Section 3 | OOPS, C++, JAVA, HTML: OOPS with C++, Java, HTML Basics, CSS
  18. Section 3 | Java: Java Fundamentals, Array, String, IO & References
  19. Section 3 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  20. Section 3 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  21. Section 3 | Multimedia: Multimedia
  22. BPSC Previous Year Papers:
  23. BPSC Full Mock Tests:
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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