TCS Placement: Sample Questions 338 - 339 of 502

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Question 338


Describe in Detail


What are the functions of the Physical layer?


Coordinates the transmission of bit stream over a physical medium.

  • Interface

    Defines the transmission interface between devices and transmission medium.

  • Representation of bits
    • Data consists of stream of bits which are encoded into signals for transmission.
    • Defines type encoding i.e.. . how 0՚s and 1՚s are changed to signal.
  • Data rate

    Defines the rate of transmission- the number of bits per second.

  • Synchronization of bits

    Deals with synchronization of the transmitter and receiver. Sender and receiver are synchronized at bit level.

  • Link configuration

    Connects devices with the medium through point-to-point or multipoint configuration.

  • Topology

    Devices can be connected using following topologies: mesh, star, ring, or bus.

  • Transmission mode

    Defines the direction of transmission between two devices: simplex, half-duplex, or dull duplex.

  • Deals with baseband and broadband transmission.

Question 339


Describe in Detail


When is a system in safe state?


  • If the system can allocate resources to the process in such a way that it can avoid deadlock- system is then in a safe state.
  • The set of dispatch able processes is in a safe state if there exists at least one temporal order in which all processes can be run to completion without resulting in a deadlock.
  • When a process requests an available resource, system must decide if immediate allocation leaves the system in a safe state.
  • System is in safe state if there exists a safe sequence of all processes.
  • A state is safe is the system can allocate resources to each process in some order and still avoids a deadlock.
  • More formally, a system is in a safe state only if there exists a safe sequence.
Given the Image is Defining the Example of Safe State

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