在计算机系统中，为了提高主存利用率，往往把辅助存储器（如磁盘）作为主存储器的扩充，使多道运行的作业的全部逻辑地址空间总和可以超出主存的绝对地址空间。-in computer systems, in order to raise the utilization rate of main memory, often auxiliary memory (such as disk) as a main memory expansion. Multi-channel operation so that the operations of all logical address space can exceed the sum of the absolute main memory address space.