要求按Q键返回操作系统，按其他键开始顺序显示256种ASCII字符。显示方法是每按一次键在屏幕左上右下的斜线上显示一串相同字符，下一次换下一个相邻字符（即从ASCII值0开始，每次值递增1）。并且要求每隔5秒屏幕上角显示一个笑脸字符，该笑脸字符交替变脸。-Requested by the Q key to return to the operating system, according to other key sequence shows the beginning of 256 kinds of ASCII characters. Shows that every time is key right on the screen left of the slash to show the same string of characters, off an adjacent next character (ASCII value 0 from the beginning of each incremental value of 1). And ask every 5 seconds the screen corner displays a smiley face characters, the characters alternately smiling face.