Correct Answer: For load-time dynamic linking: Load module to be loaded is read into memory Any reference to a target external module causes that module to be loaded and the references are updated to a relative address from the start base address of the application module With run-time dynamic loading: Some of the linking is postponed until actual reference during execution Then the correct module is loaded and linked
3. In the context of memory management, what are placement and replacement algorithms?
Correct Answer: Placement algorithms determine where in available real-memory to load a program Common methods are first-fit, next-fit, best-fit Replacement algorithms are used when memory is full, and one process (or part of a process) needs to be swapped out to accommodate a new program The replacement algorithm determines which are the partitions to be swapped out
Correct Answer: We encounter cycle stealing in the context of Direct Memory Access (DMA) Either the DMA controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarily suspend operation The latter technique is called cycle stealing Note that cycle stealing can be done only at specific break points in an instruction cycle
5. What is the resident set and working set of a process?
Correct Answer: Resident set is that portion of the process image that is actually in real-memory at a particular instant Working set is that subset of resident set that is actually needed for execution (Relate this to the variable-window size method for swapping techniques)
Correct Answer: Windows NT uses protection mechanism called rings provides by the process to implement separation between the user mode and kernel mode
Correct Answer: Virtual memory is hardware technique where the system appears to have more memory that it actually does This is done by time-sharing, the physical memory and storage parts of the memory one disk when they are not actively being used