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Binary Logic

NIOS · Class 12 · Computer Science

Quick revision notes for Binary Logic — NIOS Class 12 Computer Science. Key concepts, formulas, and definitions for last-minute revision.

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Key Topics to Revise

1

2.1 Number Systems

  • A number system defines how numbers are represented using a specific set of digits and a base (radix).
  • Binary (Base 2): Uses only digits 0 and 1. This is what computers use internally.
  • Octal (Base 8): Uses digits 0 to 7. Useful for compact representation of binary numbers.
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2.2 One's Complement and Two's Complement

  • Complement operations are used in computers to perform subtraction using addition circuits, saving hardware complexity.
  • One's Complement: Flip all bits — change every 0 to 1 and every 1 to 0.
  • Two's Complement: First find One's Complement, then add 1 to the LSB (rightmost bit).
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2.3 Character Coding Systems – ASCII, ISCII and Unicode

  • Computers only understand numbers, so characters (letters, symbols, digits) are represented using numeric codes.
  • ASCII (American Standard Code for Information Interchange): A 7-bit code that can represent 128 characters (0–127). Extended ASCII uses 8 bits for 256 characters.
  • ASCII value of 'A' = 65, 'B' = 66, ... 'Z' = 90. Lowercase 'a' = 97, ... 'z' = 122.
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2.4 Logic Gates

  • Logic gates are the elementary building blocks of digital circuits. They process binary inputs (0 or 1) to produce a binary output.
  • Most logic gates have TWO inputs and ONE output.
  • Basic gates: AND, OR, NOT. Derived gates: NAND, NOR. Special gates: XOR, XNOR.

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Key Concepts

The binary number system uses onlyThe octal number system uses 8The hexadecimal number system uses 16Converting between number systems isOne's complement is obtained by inverting

Frequently Asked Questions

What are the important topics in Binary Logic for NIOS Class 12 Computer Science?
Binary Logic covers several key topics that are frequently asked in NIOS Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Binary Logic — NIOS Class 12 Computer Science?
Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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