INT 15 - Advanced Power Management Specification - INSTALLATION CHECK
AX = 5300h
BX = 0000h (device ID of system BIOS)
Return: CF clear if successful
AH = major version (BCD)
AL = minor version (BCD)
BX = 504Dh ("PM")
CX = flags
bit 0: 16-bit protected mode interface supported
bit 1: 32-bit protected mode interface supported
bit 2: CPU idle call reduces processor speed
bit 3: BIOS power management disabled
bits 4-7 reserved
CF set on error
AH = error code (86h) (see below)

Values for 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-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


155300BX0000 - Advanced Power Management Specification - INSTALLATION CHECK