Int 10 Fn 07  - Video - Scroll Down Window                                 [V]

   AH = 07h
   AL = number of lines by which to scroll down (00h=clear entire window)
   BH = attribute used to write blank lines at top of window
   CH,CL = row,column of window's upper left corner
   DH,DL = row,column of window's lower right corner

Note:  affects only the currently active page (see AH=05h)
Warning: some implementations have a bug which destroys BP

See Also: AH=06h,AH=72h,AH=73h,INT 50/AX=0014h