Answer all the questions below. Q.1.1 Discuss the main difficulty that a programmer must overcome in writing an operating (10) system for a real-time environment. Q.1.2 Explain the function of the Page Map Table in all the memory allocation schemes that (10) make use of it. Explain your answer by describing how the PMT is referenced by other pertinent tables in each scheme. Q.1.3 Differentiate between multiprogramming and multiprocessing. (10) Q.1.4 Early versions of UNIX were available only with a command-driven interface. In more recent years, graphical user interfaces became popular. Explain why these GUls made an impact on the popularity of this operating system. Q.1.5 Discuss the following. Q.1.5.1 The cause of thrashing. Q.1.5.2 How does the system detect thrashing? (5) Q.1.5.3 Once it detects thrashing, what can the system do to eliminate this problem? (5) (5) Q.1.6 Consider a system with 13 dedicated devices of the same type and all jobs currently running on this system require a maximum of three devices to complete their execution but they each run for long periods of time with just two devices and request the remaining one only at the very end of the run. Assume that the job stream is endless and that your operating system's device allocation policy is a very conservative one. No job will be started unless all the required drives have been allocated to it for the entire duration of its run. Q.1.6.1 What is the maximum number of jobs that can be in progress at once? Explain your answer. Q.1.6.2 Explain the minimum and maximum numbers of devices that may be idle as a result of this policy. Q.1.6.3 Under what circumstances would an additional job would be started? Q.1.7 Discuss the essential properties of the following types of operating systems. Q.1.7.1 Batch. Q.1.7.2 Interactive. Q.1.7.3 Time sharing. Q.1.7.4 Real time. Q.1.7.5 Distributed