Digital Codes Overview
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Questions and Answers

What is the Excess-3 code for the decimal digit 5?

  • 1100
  • 1000
  • 1011 (correct)
  • 1001
  • Which of the following codes is specifically designed to represent decimal digits using exactly two bits set to 1?

  • 2-out-of-5 code (correct)
  • Gray code
  • Self-Complement code
  • Excess-3 code
  • What is the primary characteristic of Gray code?

  • Every combination differs by two bits
  • It has four bits for each decimal digit
  • Only one bit differs between successive values (correct)
  • It's a weighted code
  • In a 2-out-of-5 code, how many unique combinations can represent decimal digits?

    <p>10</p> Signup and view all the answers

    What is the binary representation of the decimal number 4 in Excess-3 code?

    <p>1001</p> Signup and view all the answers

    Which of the following codes aids in error correction for digital communications?

    <p>Gray code</p> Signup and view all the answers

    What operation commonly uses a shift count code in programming?

    <p>Bit manipulation</p> Signup and view all the answers

    Which code has a property where no digit representation has more than one bit difference?

    <p>Gray code</p> Signup and view all the answers

    What is a characteristic of weighted codes?

    <p>Each digit has a specific weight based on its position.</p> Signup and view all the answers

    Which of the following codes is self-complementing?

    <p>Reflective codes</p> Signup and view all the answers

    How many bits are required in BCD to represent a number with 3 decimal digits?

    <p>12 bits</p> Signup and view all the answers

    What is the binary representation of the decimal number 185 in BCD?

    <p>0011 1001 0110</p> Signup and view all the answers

    Which of the following statements about BCD is correct?

    <p>Numbers from 0 to 9 are the only valid representations in BCD.</p> Signup and view all the answers

    What defines sequential codes?

    <p>Each succeeding code is greater than the last.</p> Signup and view all the answers

    What is the primary function of error detecting and correcting codes?

    <p>To allow for identification and rectification of errors.</p> Signup and view all the answers

    Which of the following is NOT a type of digital code?

    <p>Reflection Codes</p> Signup and view all the answers

    What is the purpose of parity bits in error-detecting codes?

    <p>They help identify errors in data.</p> Signup and view all the answers

    Given the blocks 1011 and 0001, how is the first block expanded to a 7-bit representation?

    <p>The fourth bit is determined by $b5 + b6 + b7$ being even.</p> Signup and view all the answers

    How is the parity bit P1 calculated in the 8-bit data structure?

    <p>P1 is the XOR of D3, D5, D7, D9, and D11.</p> Signup and view all the answers

    What does BCD stand for in alphanumeric codes?

    <p>Binary Coded Decimal</p> Signup and view all the answers

    What range of characters can be represented using the standard BCD code?

    <p>64 characters</p> Signup and view all the answers

    In parity bit error detection, if bits 1 and 2 are incorrect, where is the error likely to occur?

    <p>In bit 3 only.</p> Signup and view all the answers

    What is the characteristic of the minimal bit representation for standard alphanumeric codes?

    <p>It can express one character using 6 bits.</p> Signup and view all the answers

    What is the maximum number of characters that can be represented in ASCII code?

    <p>128 characters</p> Signup and view all the answers

    Which of the following correctly describes the EBCDIC code?

    <p>Uses 8 bits for character representation</p> Signup and view all the answers

    Which of the following represents a common error when understanding error detection?

    <p>Not recognizing that error detection is different from error correction.</p> Signup and view all the answers

    In ASCII, which bit is considered the parity bit for advancements in error-checking?

    <p>Bit 7</p> Signup and view all the answers

    Identify the correct statement regarding the characters represented in EBCDIC code.

    <p>It includes lowercase letters, numbers, and special characters.</p> Signup and view all the answers

    Which hexadecimal code represents the carriage return (CR) in ASCII?

    <p>0D</p> Signup and view all the answers

    What does the term 'zone bit' in ASCII refer to?

    <p>It denotes the type of character being used.</p> Signup and view all the answers

    What character does the binary value 0001 in EBCDIC represent?

    <p>Start of Heading (SOH)</p> Signup and view all the answers

    Which of the following correctly describes the difference between EBCDIC and ASCII?

    <p>ASCII is primarily used on personal computers, while EBCDIC is used on mainframes.</p> Signup and view all the answers

    What is a key advantage of using Gray Code in numerical representation?

    <p>Only one bit changes between two consecutive numbers.</p> Signup and view all the answers

    Which of the following correctly describes the function of a parity bit?

    <p>It ensures that the total number of 1's is either even or odd.</p> Signup and view all the answers

    What is the minimum number of parity bits required when encoding a message of 4 data bits using Hamming code?

    <p>3 parity bits</p> Signup and view all the answers

    How does the addition of multiple parity bits affect communication efficiency?

    <p>It may lead to decreased efficiency.</p> Signup and view all the answers

    In Hamming code, what does the relationship '$d \geq 5$ and $d \leq 11$' indicate?

    <p>The threshold for the number of parity bits needed.</p> Signup and view all the answers

    Which of the following best explains why Hamming code uses even parity?

    <p>It simplifies the error detection process.</p> Signup and view all the answers

    What does the notation 'p' represent in the context of error-detecting codes?

    <p>The number of parity bits.</p> Signup and view all the answers

    Which operation is used to convert between Binary and Gray codes?

    <p>XOR (⊕)</p> Signup and view all the answers

    Study Notes

    Digital Codes: Overview

    • Digital data is represented and processed as a group of bits, also known as a binary code.
    • Weighted codes: Each digit has a specific weight based on its position.
    • Non-weighted codes: Digits are not positionally weighted.
    • Reflective codes: The code for a digit is the complement of the code for its inverse (for example, the code for 9 is the inverse of the code for 0).
    • Sequential codes: Each code is one binary value higher than the previous code.
    • Alphanumeric codes: These represent numbers, alphabet characters, and symbols.
    • Error-detecting and correcting codes: Detect errors in data communication and processing.

    Numeric Codes

    • BCD (Binary Coded Decimal): A number with k decimal digits requires 4k bits.
      • Example: Decimal 396 represented in BCD is 0011 1001 0110 (12 bits).
      • Each group of 4 bits directly corresponds to one decimal digit.
      • The binary combinations 1010 through 1111 are not used in BCD.
    • Excess-3 code: BCD code + 0011.
      • It also has a self-complementing characteristic.
    • Other Non-weighted Codes:
      • 2-out-of-5 code: Each decimal digit is represented by 5 bits, with exactly two bits set to 1 and the rest set to 0.
      • Shift count code: Describes the number of bit shifts in a binary number. Used for tasks like bit manipulation.
      • Gray code: A system where two successive values differ in only one bit. Useful for error detection and analog-to-digital conversion.

    Gray Code Properties

    • Only one bit changes between successive values.
    • Used in Analog to Digital Converters (ADCs) for error detection and reducing power consumption.

    Error-Detecting Codes

    • Parity: An extra bit (parity bit) is added to make the total number of 1s in a message either even or odd.
    • Hamming Code: Uses multiple parity bits to detect and correct single-bit errors.
      • Number of bits n needed for error detection/correction is related to the number of data bits d:
        • 2 ^(n-1)-n+1 <= d <= 2 ^(n-1)-n-1.
      • Example: 4 parity bits are required if you have 5 to 11 data bits.

    Hamming Code Implementation

    • Parity bits are placed at positions 1, 2, 4, 8, and so on, depending on the location of the parity.
    • Data bits fill the remaining locations.

    Alphanumeric Codes

    • Standard BCD Code: Expresses one character using 6 bits.
      • Maximum of 64 characters can be represented.
      • Used in specialized digital systems.
    • EBCDIC (Extended Binary Coded Decimal Interchange Code): Uses 8 bits to represent characters.
    • ASCII (American Standard Code for Information Interchange):
      • Uses 7 bits (128 unique characters) for personal computers, and often 8 bits (with added parity) for communications.
      • Each character is divided into a zone bit and a digit bit.

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    Related Documents

    ch3.pptx

    Description

    This quiz explores various types of digital codes, including weighted, non-weighted, reflective, sequential, and alphanumeric codes. It covers the basics of Binary Coded Decimal (BCD) and error-detecting codes. Test your understanding of how digital data is represented and processed.

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