Format of ACPI Firmware ACPI Control Structure

Offset  Size    Description     (Table M076)
 00h  4 BYTEs  signature "FACS"
 04h   DWORD   length of entire structure in bytes (>= 40h)
 08h   DWORD   value of system's hardware signature at last boot
 0Ch   DWORD   real-mode ACPI OS waking vector
       if nonzero, control is transferred to this address on next BIOS
         POST
 10h   DWORD   global lock (see #M077)
 14h 44 BYTEs  reserved (0)

Note:  this structure is located on a 64-byte boundary anywhere in the
     first 4GB of memory

See Also: #M069
Bitfields for ACPI Embedded Controller Arbitration Structure:
Bit(s) Description (Table M077)
 0 request for Global Lock ownership is pending
 1 Global Lock is currently owned
 2-31  reserved

See Also: #M076