In this chapter you will learn about the following: Characteristics of users that every software engineer should understand; various ways of working with users to ensure that a software system has both the required functionality and the required usability; some basic principles for the design of simple graphical user interfaces (GUIs), involving windows, menus, icons and pop-up dialogs; how to evaluate user interfaces; how to implement basic GUIs in Java. | Module 8: Memory Management Background Logical versus Physical Address Space Swapping Contiguous Allocation Paging Segmentation Segmentation with Paging Operating System Concepts Background Program must be brought into memory and placed within a process for it to be executed. Input queue – collection of processes on the disk that are waiting to be brought into memory for execution. User programs go through several steps before being executed. Operating System Concepts Binding of Instructions and Data to Memory Compile time: If memory location known a priori, absolute code can be generated; must recompile code if starting location changes. Load time: Must generate relocatable code if memory location is not known at compile time. Execution time: Binding delayed until run time if the process can be moved during its execution from one memory segment to another. Need hardware support for address maps (., base and limit registers). Address binding of instructions and data to memory . | Module 8: Memory Management Background Logical versus Physical Address Space Swapping Contiguous Allocation Paging Segmentation Segmentation with Paging Operating System Concepts Background Program must be brought into memory and placed within a process for it to be executed. Input queue – collection of processes on the disk that are waiting to be brought into memory for execution. User programs go through several steps before being executed. Operating System Concepts Binding of Instructions and Data to Memory Compile time: If memory location known a priori, absolute code can be generated; must recompile code if starting location changes. Load time: Must generate relocatable code if memory location is not known at compile time. Execution time: Binding delayed until run time if the process can be moved during its execution from one memory segment to another. Need hardware support for address maps (., base and limit registers). Address binding of instructions and data to memory addresses can happen at three different stages. Operating System Concepts Dynamic Loading Routine is not loaded until it is called Better memory-space utilization; unused routine is never loaded. Useful when large amounts of code are needed to handle infrequently occurring cases. No special support from the operating system is required implemented through program design. Operating System Concepts Dynamic Linking Linking postponed until execution time. Small piece of code, stub, used to locate the appropriate memory-resident library routine. Stub replaces itself with the address of the routine, and executes the routine. Operating system needed to check if routine is in processes’ memory address. Operating System Concepts Overlays Keep in memory only those instructions and data that are needed at any given time. Needed when process is larger than amount of memory allocated to it. Implemented by user, no special support needed from operating system, programming design of overlay structure is .
