What decides a device to be a pnp or non_pnp device?

Discussion in 'Windows Vista Drivers' started by jun, Nov 19, 2003.

  1. jun

    jun Guest

    I don't know why a device is a pnp device, and another one is a non_pnp
    Is a USB device a pnp device, and a serial port device is not pnp?
    jun, Nov 19, 2003
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  2. If the hardware spec for that device defines some kind of PnP the device is
    a PnP one :)
    Depends. If you are referring to the on-board COM port that it's up to BIOS.
    I.e. if you have ACPI BIOS the COM port is essentially PnP device.

    Kirk Ferdmann, Nov 19, 2003
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  3. "PnP devices" are by definition - "devices which can report their
    identity/part number/hardware resources to the OS by bus-standard means".

    All sane USB devices are PnP, since USB requires the device to implement
    the config descriptors.
    All sane PCI devices are PnP, since PCI requires the device to implement
    the config space.
    Same on 1394, IDE and SCSI.

    As about the serial port - there is a "serial PnP protocol" (set the port
    to some state, and the device must print its PnP ID to the host), which is a
    developed version of MS/Mouse Systems mouse identification and button counting
    protocol :).
    Nevertheless, not all serial devices support this (all mice support a
    primitive subset of it, and all modern modems seem to support it, but lots of
    serial hardware does not support). Thus - non-PnP serial devices.
    Maxim S. Shatskih, Nov 19, 2003
  4. Generally the hardware connectivity to the system will make the call. If
    the interface is a bus (PCI, USB, 1394, SCSI, etc.) for which the Standard
    defines that the hardware enumerate (i.e. identify) itself in some fashion,
    then it most likely is a PnP device; otherwise it is a legacy or non-PnP
    device (i.e. ISA, over IP, etc.).

    As to whether a serial port is PnP or not, it depends upon how it is
    connected to the system. A standard hardware serial port generally is a PnP
    device as it is directly connected to the motherboard and often is reported
    to the system via the BIOS.

    As for serial port extensions (i.e. a Multi-Port Serial adapter), whether it
    is a PnP device or not depends upon how it is enumerated to the system. In
    our case, we have the adapter which may or may not be a PnP device (i.e. if
    it is connected via PCI or over IP), but acts like a bus adapter which in
    turn enumerates the ports to the system, making them PnP devices.
    Del Fredricks, Nov 19, 2003
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