Int 15 Fn 5300  - Advanced Power Management V1.0+ - Installation Check     [p]

   AX = 5300h
   BX = device ID of system BIOS (0000h)

Return: CF clear if successful
       AH = major version (BCD)
       AL = minor version (BCD)
       BX = 504Dh ("PM")
       CX = flags (see #0398)
   CF set on error
       AH = error code (06h,09h,86h) (see #0399)
BUG:   early versions of the Award Modular BIOS with built-in APM support
     reportedly do not set BX on return

Bitfields for APM flags:
Bit(s) Description (Table 0398)
 0 16-bit protected mode interface supported
 1 32-bit protected mode interface supported
 2 CPU idle call reduces processor speed
 3 BIOS power management disabled
 4 BIOS power management disengaged (APM v1.1)
 5-7   reserved

(Table 0399)
Values for APM error code:
 01h   power management functionality disabled
 02h   interface connection already in effect
 03h   interface not connected
 04h   real-mode interface not connected
 05h   16-bit protected-mode interface already connected
 06h   16-bit protected-mode interface not supported
 07h   32-bit protected-mode interface already connected
 08h   32-bit protected-mode interface not supported
 09h   unrecognized device ID
 0Ah   invalid parameter value in CX
 0Bh   (APM v1.1) interface not engaged
 0Ch   (APM v1.2) function not supported
 0Dh   (APM v1.2) Resume Timer disabled
 0Eh-1Fh reserved for other interface and general errors
 20h-3Fh reserved for CPU errors
 40h-5Fh reserved for device errors
 60h   can't enter requested state
 61h-7Fh reserved for other system errors
 80h   no power management events pending
 81h-85h reserved for other power management event errors
 86h   APM not present
 87h-9Fh reserved for other power management event errors
 A0h-FEh reserved
 FFh   undefined