该程序是用汇编语言编写的，采用COM 文件格式。主要设计思想为：把目录当作N个结点的二叉树， 采用二叉树的先序遍历完成对盘上目录的搜索、定位，即从根目录开始用INT21H的 4EH号子功能搜索匹配目录（CL=10H）并判断搜索的结果是否为目录，若是则进入此目录，删除文件后继续搜索下一级子目录。若不是则用INT21H的4FH号子功能搜索下一个匹配目录， 并在判断为真后进入目录删除文件，如此一级一级地纵向深入子目录删除文件，直到完成此目录的最后一级子目录的文件删除（遍历左子树）。然后用INT21的4FH号横向搜索此目录的上一级子目录中的匹配目录（遍历右子树），接着再纵向删除文件，如此循环下去，直到完成整棵树的遍历。此时根目录下的所有需要删除的文件已全部被删除。程序通过递归调用目录定位及删除文件子程序实现上述算法，即SEARCHDIR子程序，因此这段子程序是整个程序的核心。-the program is written in assembly language, using COM files. The main design ideas : put directory as N nodes of a binary tree using binary tree preorder completion of the plate directory search, positioning, from the root directory started INT21H 4EH, the son of matching directory search function (CL = 10H), and to judge whether the outcome of the search for the directory, if yes, it may enter this directory, delete files after a search under subdirectory. If they are used, INT21H son has the search function under a matching directory and judgment entered for the really delete the file directory, so a vertical depth to a subdirectory delete the file until completion of this directory a subdirectory of the final document deleted (traverse left subtree). Then the INT21 has its horizontal s