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The correct CHOICE is (b) Automatic BUFFERING

The best explanation: Bounded CAPACITY and Unbounded capacity QUEUES are referred to as Automatic buffering. Buffer capacity of the Bounded capacity queue is finite length and buffer capacity of the Unbounded queue is infinite.

Right OPTION is (b) is REFERRED to as a message system with no buffering

For EXPLANATION: The Zero capacity queue is referred to as a message system with no buffering. Zero capacity queue has maximum capacity of Zero; thus message queue does not have any WAITING message in it.

The correct answer is (B) the sender BLOCKS until the receiver receives the message

Best EXPLANATION: In the Zero capacity queue the sender blocks until the receiver receives the message. Zero capacity queue has maximum capacity of Zero; thus message queue does not have any WAITING message in it.

Right option is (b) the sending PROCESS sends the message and resumes operation

The explanation: In the non blocking SEND, the sending process sends the message and resumes operation. Sending process doesn’t CARE about reception. It is also KNOWN as asynchronous send.

Right option is (C) there is a mailbox to help communication between P and Q

Easiest EXPLANATION - In indirect communication between processes P and Q there is a mailbox to help communication between P and Q. A mailbox can be viewed abstractly as an OBJECT into which messages can be placed by processes and from which messages can be removed.

Correct OPTION is (b) A communication link is ASSOCIATED with exactly two processes

Easiest EXPLANATION - For direct communication, a communication link is associated with exactly two processes. ONE communication link must exist between a pair of processes.

The correct answer is (a) COMMUNICATION link

The explanation: The link between two PROCESSES P and Q to send and receive messages is called communication link. Two processes P and Q WANT to communicate with each other; there should be a communication link that must exist between these two processes so that both processes can ABLE to send and receive messages using that link.

The correct option is (c) can be FIXED or variable sized

Explanation: Messages sent by a process can be fixed or variable size. If the message size of the process is fixed then system LEVEL implementation is straightforward but it makes the TASK of PROGRAMMING more DIFFICULT. If the message size of the process is variable then system level implementation is more complex but it makes the task of programming simpler.

Correct choice is (d) receive & SEND message

Explanation: TWO OPERATIONS provided by the IPC facility are receive and send messages. Exchange of data takes place in cooperating processes.

The correct choice is (a) communicate with each other without SHARING the same address space

The best EXPLANATION: MESSAGE Passing system ALLOWS processes to communicate with each other without sharing the same address space.

Right answer is (b) ALLOWS processes to communicate and synchronize their actions

Explanation: Interprocess Communication allows processes to communicate and synchronize their actions. Interprocess Communication (IPC) mechanism is used by COOPERATING processes to EXCHANGE data and information.

There are two models of IPC:

 → SHARED Memory

 → Message PASSING

Correct choice is (b) Zombie

Explanation: The CHILD PROCESS completes execution, but the PARENT KEEPS executing, then the child process is known as Zombie. When a child process terminates, its resources get deallocated but its entry in the Process CONTROL Block (PCB) remains there until its parent calls wait system call.

The correct ANSWER is (a) be a duplicate of the PARENT PROCESS

To explain I would say: The child process can be a duplicate of the parent process. The child process created by FORK consists of a copy of the address SPACE of the parent process.

Right option is (c) Zero, A NONZERO integer

The explanation is: In Unix, the RETURN value of the fork SYSTEM CALL is Zero for the child PROCESS and Non-zero value for parent process. A fork system call returns the PID of a newly created (child) process to the parent and returns Zero to that newly created (child) process.

The CORRECT option is (C) Process IDENTIFIER

The explanation: In UNIX, each process is identified by its Process Identifier or PID. The PID PROVIDES unique value to each process in the system so that each process can be identified uniquely.

Right ANSWER is (C) Normally or abnormally

The explanation is: Cascading termination refers to termination of all CHILD processes if the PARENT process terminates Normally or Abnormally. Some systems don’t allow child processes to exist if the parent process has terminated. Cascading termination is normally initiated by the OPERATING system.

Right answer is (a) wait

To explain I would say: A parent process calling wait system CALL will be suspended until children PROCESSES terminate. A parameter is passed to wait system call which will obtain exit status of child as WELL as wait system call returns PID of terminated process.

Correct answer is (c) overloading the SYSTEM by creating a lot of sub-processes

To explain I would SAY: Restricting the child process to a subset of the parent’s resources prevents any process from overloading the system by creating a lot of sub-processes. A process creates a child process, child process requires CERTAIN resources to complete its task. A child process can DEMAND required resources directly from the system, but by doing this system will be overloaded. So to avoid overloading of the system, the parent process SHARES its resources among children.

Correct ANSWER is (d) all of the mentioned

Easy explanation - A monitor is a module that ENCAPSULATES shared data structures, procedures that operate on shared data structure, SYNCHRONIZATION between concurrent PROCEDURE invocation.

Right CHOICE is (a) priority inversion

The best explanation: When a HIGH priority TASK is indirectly preempted by a MEDIUM priority task effectively inverting the relative priority of the two tasks, the scenario is CALLED priority inversion.

Correct choice is (c) both mutex LOCKS and binary semaphores

The best I can explain: Mutual EXCLUSION can be provided by both mutex locks and binary semaphore. Mutex is a short FORM of Mutual Exclusion. Binary semaphore also PROVIDES a mechanism for mutual exclusion. Binary semaphore BEHAVES similar to mutex locks.

Right CHOICE is (a) that can not drop below ZERO

Explanation: A semaphore is a shared integer variable that can not drop below zero. In binary semaphore, if the value of the semaphore variable is zero that means there is a process that uses a CRITICAL RESOURCE and no other process can access the same critical resource until it is released. In COUNTING semaphore, if the value of the semaphore variable is zero that means there is no resource available.

The correct OPTION is (c) semaphore

Easy EXPLANATION - Semaphore is a synchronization TOOL. Semaphore is a mechanism which synchronizes or controls access of threads on CRITICAL resources. There are two types of semaphores i) Binary Semaphore ii) COUNTING Semaphore.

Correct answer is (a) mutual exclusion

The best I can explain: If a process is executing in its critical section, then no other processes can be executed in their critical section. This condition is called Mutual Exclusion. Critical section of the process is SHARED between MULTIPLE processes. If this section is executed by more than one or all of them concurrently then the OUTCOME of this is not as PER DESIRED outcome. For this reason the critical section of the process should not be executed concurrently.

Right option is (b) race CONDITION

The explanation: When several processes access the same data concurrently and the OUTCOME of the EXECUTION depends on the PARTICULAR order in which access TAKES place is called race condition.

Right ANSWER is (c) SCHEDULER process

The BEST I can explain: Scheduler process does not interrupt a RUNNING process. Scheduler process selects an available process from a POOL of available processes and allocates CPU to it.

Right CHOICE is (d) context switch time

To explain: The context of a PROCESS in the PCB of a process does not CONTAIN context switch time. When switching CPU from one process to another, the current context of the process NEEDS to be saved. It includes values of the CPU registers, process states, memory-management information.

The correct answer is (b) READY state

Easy explanation - Suppose that a PROCESS is in “Blocked” state waiting for some I/O service. When the service is completed, it goes to the ready state. Process never goes directly to the RUNNING state from the waiting state. Only PROCESSES which are in ready state go to the running state whenever CPU allocated by operating system.

The CORRECT option is (b) Ready state

Easiest explanation - In a time-sharing operating system, when the time SLOT given to a process is completed, the process goes from the RUNNING state to the Ready State. In a time-sharing operating system unit time is defined for sharing CPU, it is called a time QUANTUM or time slice. If a process takes less than 1 time quantum, then the process itself RELEASES the CPU.

Correct choice is (a) block

The BEST EXPLANATION: The only state TRANSITION that is INITIATED by the USER process itself is block. Whenever a user process initiates an I/O request it goes into block state unless and until the I/O request is not completed.

Correct OPTION is (c) The FREQUENCY of their EXECUTION

To explain I would say: The primary DISTINCTION between the short-term scheduler and the long-term scheduler is the frequency of their execution. The short-term scheduler EXECUTES frequently while the long-term scheduler executes much less frequently.

Correct answer is (b) It SELECTS which PROCESS has to be EXECUTED next and ALLOCATES CPU

To EXPLAIN: A short-term scheduler selects a process which has to be executed next and allocates CPU. Short-term scheduler selects a process from the ready queue. It selects processes frequently.

The correct option is (c) It selects which process to remove from memory by swapping

Easy explanation - A medium-term SCHEDULER selects which process to remove from memory by swapping. The medium-term scheduler SWAPPED out the process and LATER swapped in. Swapping helps to free up memory.

Correct option is (c) empty, LITTLE

For explanation: If all processes are I/O bound, the READY QUEUE will almost empty and the short-term SCHEDULER will have a little to do. I/O bound processes spend more time doing I/O than computation.

Right OPTION is (a) It selects processes which have to be brought into the ready queue

For explanation: A long-term scheduler selects processes which have to be brought into the ready queue. When processes enter the SYSTEM, they are put in the JOB queue. Long-term scheduler selects processes from the job queue and puts them in the ready queue. It is ALSO known as Job Scheduler.

The CORRECT option is (a) It is removed from all queues

For EXPLANATION: When a process terminates, it removes from all queues. All allocated resources to that particular process are deallocated and all those resources are returned BACK to OS.

The correct choice is (a) It is placed in an I/O QUEUE

Explanation: When the process issues an I/O request it is placed in an I/O queue. I/O is a resource and it should be used effectively and every process should get access to it. There might be multiple processes which requested for I/O. DEPENDING on scheduling algorithm I/O is ALLOCATED to any PARTICULAR process and after completing I/O operation, I/O access is RETURNED to the OS.

Right answer is (b) PCB QUEUE

For explanation: PCB queue does not belong to QUEUES for processes. PCB is a PROCESS control block which CONTAINS information related to process. Each process is represented by PCB.

Right answer is (a) only one task at a TIME

The explanation: A SINGLE THREAD of control allows the PROCESS to perform only one task at a time. In the case of multi-core, multiple threads can be run simultaneously and can perform multiple tasks at a time.

Correct ANSWER is (d) the number of processes in memory

Best explanation: Multiprogramming means the number of processes are in the ready states. To increase utilization of CPU, Multiprogramming is ONE of the most important abilities of OS. Generally, a single process cannot use CPU or I/O at all TIME, whenever CPU or I/O is AVAILABLE ANOTHER process can use it. By doing this CPU utilization is increased.

The CORRECT choice is (c) PROCESS Table

Easy EXPLANATION - The entry of all the PCBS of the CURRENT processes is in Process Table. The Process Table has the status of each and every process that is created in OS along with their PIDs.

The correct ANSWER is (b) DATA Structure

To explain I WOULD say: A Process Control BLOCK (PCB) is a data structure. It contains information related to a process such as Process State, Program Counter, CPU Register, etc. Process Control Block is also known as Task Control Block.

The correct CHOICE is (B) OLD

The best I can explain: There is no process state such as old. When a process is created then the process is in New state. When the process gets the CPU for its execution then the process is in Running state. When the process is waiting for an external EVENT then the process is in a Waiting state.