systems that have the standard ATX motherboards.
BMW has the standard OBDII connector under the drivers side dash so generic OBDII cables will work but only with generic OBDII software. Each specific software needs a compatible cable designed expressly for it.Older style 20pin cables are a similar matter.
some have none, especially newer smaller laptops that only have a few usb ports. althought a serial cable to usb connector usually works, the connection is laggier. most computers have one, maybe two. unless you are running multiple devices, one is all you need. this is in reference to a nine pin serial cable. most have a 20pin serial port for visual in/out, but this is not related to a com port. serial ports are identified as COM, usually COM1 or COM3 but each port can only be used by one thing at a time.i know very little about computer anatomy, so while i know this is partially right, someone should add correct me if i am wrong