Int 10 Fn A00C  - Ati Mach64 Bios - Set Sleep Mode                         [p]

   AX = A00Ch
   CL = new state
       00h normal operation
       01h standby
       02h suspend
       03h off

Return: AH = status
       00h successful
       01h failed

Note:  CL bit 2 affects values written to video card's ports

See Also: AX=A000h,AX=A00Dh,AX=4F00h,AX=4F10h/BL=01h