Q6. Choose the best answer for each question in this section. . (Marks for each part : 2) 1. In what way is an operating system like a government? a- It seldom functions correctly. b- It creates an environment within which other programs can do useful work. c- It performs most useful functions by itself. d- It is always concerned primarily with the individual's needs. 2. Which of the following is the only gateway between user space and kernel space? a- User interface. b- System call. c- Operating system. d- Hardware drivers. 3. Assume the shared buffer is implemented as a circular array with two logical pointers: in and out. The variable in points to the next free position in the buffer; out points to the first full position in the buffer. Which of the following is true? a- The buffer is empty when in == out; the buffer is full when (( in +1)% BUFFER SIZE) == out; b- The buffer is full when in == out; the buffer is empty when ( (in +1)% BUFFER SIZE) == out; c- All the elements of the buffer can be used; d- Both ' a ' and ' e ' 4. The list of processes waiting to execute on a CPU is called a(n) a- Standby queue b- Device queue c- Ready queue d- Interrupt queue 5. Which of the following critical-section problem's requirements ensures programs will cooperatively determine what process will next enter its critical section? a- Mutual exclusion b- Progress c- Bounded waiting d- None of the above 7. External fragmentation is a- when there is some unused memory that cannot be allocated to a process. b- when the amount of available memory is less than the size of a process. c- when a process is broken up into smaller parts for memory allocation. d- when there is enough total memory space to satisfy a request but the available spaces are no contiguous. 8. In polling I/O, the main inefficiency comes from a- the hardware controller when it notifies the CPU that the device is ready for service. b- the basic polling operation that may be comprised of several CPU instructions. c- polling when it is attempted repeatedly yet rarely finds a device ready for service. d- the slow data transfer rate between a device and the host. 9. In a blocking I/O (system call), the execution of a process is suspended a- until the process is woken up by some other process. b- until a fixed amount of time has elapsed. c- the kernel raises the priority of that process. d- the I/O has completed. 10. File's is a unique tag identifies the file within the file system. a- type b- location c- identifier d- name
