GetMaxXY PROC

   Returns the current number of columns X and rows Y in the screen's console window buffer.
   The range of each is 0-255.
   For the default screen 80x25, X=80, and Y=25.
   These values can change while a program is executing if the user modifies the properties of the application window.
   Use in conjunction with the Gotoxy procedure (the maximum argument values when calling Gotoxy are DL=(X-1) and DH=(Y-1).

Call args:   None.

Return args: DL = Current number of columns
             DH = Current number of rows


Example: Locate the cursor in the lower right
         corner of the screen:

      call GetMaxXY
      dec  dl         ;highest column number = X-1
      dec  dh         ;highest row number = Y-1

      call Gotoxy     ;to position the cursor