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1) 2) The OS can be viewed as a resource allocator 3)Multiprogramming always involves the use of multiprocessors 4) The OS masks the details of the system software from the programmer for using the system. The program counter is a register that contains the memory address of the operand to be loaded 5) Cache memory is managed by the operating system 6) Sequential processing and parallel processing are the two main approaches to handling multiple interrupts. 7) Interrupts are provided primarily as a way to improve memory utilization. 8) System calls are synchronous and interrupts are asynchronous. 9) Signal handlers reside in the user space. 10)Signals must be handled by the operating systems and cannot be ignored. 11 )--In a two-level memory hierarchy the hit ratio is defined as the fraction of all memory accesses found in the slower memory. 12) A micro-kernel operating system is implemented as a single process with all elements sharing the same address space. 13) Both multi-programmed batch processing and time sharing use multithreading. The phrase "control is passed to a job" means that the processor is now fetching and executing instructions from the monitor program 15) The principle objective of time sharing is to maximize processor use. Part 2. Short answers (70%) 1. (20%) Answer the following questions. a) The main objectives of an operating system are Convenience, and b) The main resources managed by the operating system are /'O devices