Assignment1PartASoln

Assignment1PartASoln - CSCI 5103 (Fall 2010) Answers to...

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CSCI 5103 (Fall 2010) Answers to Assignment 1 Questions and Grading Criteria Part A ( 100 points) Due September 15, 2010 This part of the assignment must be done individually . Problem 1 (20 points): Which of the following instructions should be allowed only in the privileged (kernel) mode? a) Disable all interrupts. Only in privileged mode b) Read the time-of-the-day clock. Can be executed in user mode c) Set the time-of-the day clock. Only in privileged mode d) Change the base-bound register values Only in privileged mode e) Set a timer. Hardware times can only be set in the privileged mode f)Turn off timer interrupt. Only in privileged mode g) Read from kernel memory. Only in privileged mode h) Write to kernel memory. Only in privileged mode i)Fetch an instruction from kernel memory Only in privileged mode j)Switch from user to monitor mode. In user model trap instruction can be executed for mode switching Problem 2 (15 points): What are the key differences between traps, system calls, exceptions, and interrupts? A trap is caused by the program and is synchronous with it. It is caused due to some error condition detected by the processor because of an operation executed by the program code. Examples: divide by zero, illegal memory reference, page-fault. Such errors are also commonly referred to as exceptions. A
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Assignment1PartASoln - CSCI 5103 (Fall 2010) Answers to...

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