Int 49 Fn 15  - Ti Professional Pc - Crt - Set Protected Status Area       [V]

   AH = 15h
   CL = row at which to start status area, or 00h to cancel
   CH = 00h

Return: nothing
Desc:  set a protected area of the screen which will not be affected by TTY
     writes or the scrolls they may generate

Notes: AH=00h,04h,05h,0Bh,0Ch,0Dh,0Fh are documented as NOPs
   the current cursor position must be above the status area in order to
     set the protected area

See Also: AH=01h,AH=02h