熟悉DOS编程环境：编写一个DOS环境的汇编语言程序，要求从键盘输入一串字符，并逆序显示，遇到英文字母的时候全部转换为大写字母。-Familiar with DOS programming environment: an assembly language program written in DOS environment required to enter a string of characters from the keyboard, and the reverse shows alphabetical encountered when all uppercase letters.