利用交互式命令实现树型目录结构和文件管理,同时利用位示图表示外存的分配情况，新建文件时分配必要的空间，模拟文件分配表记录文件在外存上的存储方式-Using interactive command tree directory structure and file management, at the same time use the distribution diagrams of CRT said, the new file space allocated when necessary, simulate the file allocation table record files stored on the CRT