Until 4.1.2
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Questions and Answers

Which type of keyboard has no hardware and must be analyzed by software or special hardware?

  • Mechanical keyboard
  • Virtual keyboard
  • Encoded keyboard
  • Non-encoded keyboard (correct)

    • What is the optimal number of input and output lines required to decode a 16 key device for an 8-bit controller?

  • 8 input lines and 8 output lines
  • 6 input lines and 6 output lines
  • 4 input lines and 4 output lines (correct)
  • 2 input lines and 2 output lines

    • What is the name of the process used to identify which key has been pressed in a matrix organization keyboard?

  • Walking zero pattern
  • Column scanning
  • Row scanning (correct)
  • Interrupt-driven detection

    • What is the purpose of latches and decoders in larger keyboards?

    <p>To handle more select and sense lines</p> Signup and view all the answers

    What is the benefit of using a dedicated keyboard controller hardware?

    <p>Reduces processor load</p> Signup and view all the answers

    What is the name of the pattern used to signal an interrupt for key press detection when no keys are pressed?

    <p>All 0s pattern</p> Signup and view all the answers

    What is the main factor that determines the complexity of the processor task when reading from a keyboard?

    <p>The number of keys to be detected</p> Signup and view all the answers

    What is the recommended assignment for the smaller number when selecting the key organization?

    <p>Assign it to the row lines</p> Signup and view all the answers

    What is the name of the process used to read the keyboard when a small number of keys are assigned to each buffer or port line?

    <p>Buffer sensing</p> Signup and view all the answers

    What is the name of the organization used for a keyboard with a larger number of keys, arranged in a row and column fashion?

    <p>Matrix organization</p> Signup and view all the answers

    What is the name of the hardware used to analyze a non-encoded keyboard?

    <p>Special hardware</p> Signup and view all the answers

    What is the name of the process used to identify which key has been pressed in a non-encoded keyboard?

    <p>Row scanning</p> Signup and view all the answers

    Which type of keyboard has no hardware and must be analyzed by software or special hardware?

    <p>Non-encoded keyboard</p> Signup and view all the answers

    What is the optimal number of input and output lines required to decode a 16 key device for an 8-bit controller?

    <p>4 input lines and 4 output lines</p> Signup and view all the answers

    What is the name of the process used to identify which key has been pressed in a matrix organization keyboard?

    <p>Row scanning</p> Signup and view all the answers

    What is the purpose of latches and decoders in larger keyboards?

    <p>To handle more select and sense lines</p> Signup and view all the answers

    What is the benefit of using a dedicated keyboard controller hardware?

    <p>Reduces processor load</p> Signup and view all the answers

    What is the name of the pattern used to signal an interrupt for key press detection when no keys are pressed?

    <p>All 0s pattern</p> Signup and view all the answers

    What is the main factor that determines the complexity of the processor task when reading from a keyboard?

    <p>The number of keys to be detected</p> Signup and view all the answers

    What is the recommended assignment for the smaller number when selecting the key organization?

    <p>Assign it to the row lines</p> Signup and view all the answers

    What is the name of the process used to read the keyboard when a small number of keys are assigned to each buffer or port line?

    <p>Buffer sensing</p> Signup and view all the answers

    What is the name of the organization used for a keyboard with a larger number of keys, arranged in a row and column fashion?

    <p>Matrix organization</p> Signup and view all the answers

    What is the name of the hardware used to analyze a non-encoded keyboard?

    <p>Special hardware</p> Signup and view all the answers

    What is the name of the process used to identify which key has been pressed in a non-encoded keyboard?

    <p>Row scanning</p> Signup and view all the answers

    Which type of keyboard requires hardware analysis by a software routine or by special hardware?

    <p>Non-encoded keyboards</p> Signup and view all the answers

    What is the optimal number of input and output lines for an 8-bit controller to decode a 16 key device?

    <p>4 input lines and 4 output lines</p> Signup and view all the answers

    What is the name for the organization of a keyboard in a row and column fashion with an n by m key layout?

    <p>Matrix organization</p> Signup and view all the answers

    What is the process called to identify which key has been pressed on a keyboard with a matrix organization?

    <p>Row scanning</p> Signup and view all the answers

    What is the name for the hardware used to reduce processor load when detecting a key press?

    <p>Keyboard controller</p> Signup and view all the answers

    What is the recommended assignment for the smaller number when selecting the key organization?

    <p>Row lines</p> Signup and view all the answers

    What is the name for the process of making all the column lines go to '0' volts to reduce processor load?

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

    What is the name for the hardware used to handle more select and sense lines for larger keyboards?

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

    What is the name for a keyboard that has pressure or touch-activated switches arranged in a matrix?

    <p>Non-encoded keyboard</p> Signup and view all the answers

    Which type of keyboard requires hardware to analyze the key press?

    <p>Encoded keyboards</p> Signup and view all the answers

    What is the name for the pattern output to the column lines to identify which key has been pressed?

    <p>Walking zero</p> Signup and view all the answers

    What is the name for the process of assigning one key to each buffer or port line for a small number of keys?

    <p>Direct connection</p> Signup and view all the answers

    Study Notes

    Keyboard Interfacing for Embedded Computer Systems

    • Keyboards are a common method of input to microprocessors from humans, and consist of pressure or touch-activated switches arranged in a matrix.
    • Two basic types of keyboards are available: encoded and non-encoded.
    • Non-encoded keyboards have no hardware and must be analyzed by a software routine or by special hardware.
    • For a small number of keys, we may assign one key to each buffer or port line. To read the keyboard, it is connected directly to a buffer or port.
    • For larger number of keys, the keyboard may be arranged in a row and column fashion, with an n by m key organization, known as a matrix organization.
    • A 16 key device can be decoded with 4 input lines and 4 output lines, which is optimal for an 8-bit controller as this will use one port.
    • To identify which key has been pressed, a "walking zero" pattern is output to the column lines and the row lines are sensed to see if a low voltage is detected, known as "row scanning."
    • Larger keyboards require more select and sense lines, which can be handled using latches or decoders.
    • Detecting a key press is a processor-intensive process, and dedicated keyboard controller hardware is available, which is normally interrupt-driven and has various features built into them.
    • A simple solution to reduce processor load is to make all the column lines go to "0" volts, and if no keys are pressed, all the row lines will present a "1" level, which can be ANDed together to signal an interrupt for key press detection.
    • The complexity of the processor task when reading from a keyboard depends on the number of keys to be detected, the input ports available on the processor, and the amount of processor time dedicated to this task.
    • When selecting the key organization, the smaller number should be assigned to the row lines as we detect a key press through these lines, the status of which is read into a register.

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    Description

    Test your knowledge on keyboard interfacing for embedded computer systems with this informative quiz! From encoded vs non-encoded keyboards to row scanning and key organization, this quiz covers the basics of keyboard interfacing. Whether you're a beginner or an experienced programmer, this quiz will challenge your understanding of how keyboards are used as input devices for microprocessors. Don't miss out on the chance to expand your knowledge on this important topic - take the quiz now!

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