INT 15H 5300H: Installation Check

 Expects: AX    5300H
          BX    0000H (power device ID = System BIOS)
 Returns: AH    86H = APM not installed (and CF=CY)
                APM major version number, in BCD (if CF=NC)
          AL    APM minor version number, in BCD
          BX    504dH (BH='P' and BL='M')
          CX    flags: bit 0: 1 = 16-bit protected-mode interface supported
                       bit 1: 1 = 32-bit protected-mode interface supported
                       bit 2: 1 = CPU Idle calls slow the CPU clock speed
                       bit 3: 1 = BIOS power management is disabled
                        4-15: (reserved)
    Info: This function checks to see whether the BIOS supports APM and
          obtains the version of the APM spec that is supported.

       AX the version number is in BCD; e.g., 0312H is version 3.12

       BX See INT 15H 5305H (CPU Busy) for info on bit 3.

See Also: APM API
          About APM