INT 15 - Advanced Power Management v1.1 - OEM APM INSTALLATION CHECK
AX = 5380h
BH = 7Fh
Return: CF clear if successful
BX = OEM identifier
all other registers OEM-defined
---Intel SL Enhanced Option BIOS---
BX = 534Ch ('SL')
CL = 4Fh ('O')
AL = version (10h = 1.0)
---HP APM BIOS---
BX = 4850h ('HP')
CX = version (0001h)
CF set on error
AH = error code (03h) (see #00473)
SeeAlso: AX=5380h/BH=00h