说明：  在指定的位置，用指定的颜色，显示一个用0结束的字符串。（dh）=行号（取值范围0~24），（dl）=列号（取值范围0~79），（cl）=颜色，ds:si指向字符串的首地址，无返回。在屏幕的8行3列用绿色显示data段中的字符串‘Welcome to masm!’,0
(In the specified location, display a string with 0 in the specified color. (dh) = line number (range of values 0-24), (dl) = column number (range of values 0-79), (cl) = color, ds: Si points to the first address of the string, no return. In the 8 row and 3 column of the screen, use green to display the string in the data segment "Welcome to MASM!", 0)