Physical and Virtual Memory 浙江 陈剑波 1996-11-15 Virtual memory is memory that appears to be allocated to application programs. The operating system uses a portion of the hard disk as virtual memory,swapping data and instructions beween the hard disk and physical memory. Virtual memory makes multitasking possible. In a multitasking session,the memory reqirements of all the programs that might be running in the system at the same time can far exceed the amount of phsical memory that is available. The operating system allocates virtual memory to meet the total memory requirements of each program,and then manages the available phsical memory to meet the actual requirements at vigen point in time. Thus,the amount of virtual memory that is allocated can be much greater than the amount of physical memory installed in the computer. 物理内存和虚拟内存 物理内存包括所有位于计算机内的可写内存。物理内存用于储存诸如操作系统、视频数据及计算机用于运行程序的指令和数据之类的内容。 虚拟内存是表现为分配给应用程序的内存。操作系统使用硬盘的一部分作为虚拟内存，在硬盘和物理内存之间交换数据和指令。 虚拟内存使多任务成为可能。在执行多任务期间，可能在同一时间内在系统中运行的所有程序的内存需求可以远超过可用的物理内存容量。操作系统就分配虚拟内存以满足每个程序的总的内存需求，然后管理可用的物理内存以便及时地在给定的时刻满实际的内存需求。所以，被分配的虚拟内存的容量可以远远大于计算机内安装的物理内存容量。