This article was previously published under Q133159
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This article contains questions and answers about Plug and Play support in
- Q. What is the difference between detection and enumeration in
A. Detection is the process Windows uses during its search for
legacy, or non-Plug and Play, devices on a computer. Detection is
used during Windows Setup and any time you use the Add New
Hardware Wizard to search for new hardware installed in your
computer. Detection does not run each time you start Windows.
During the detection process, Windows creates a file called
Detlog.txt in the root directory of the boot drive. This file
exists primarily as a troubleshooting tool.
Enumeration is the process Windows uses to identify Plug and Play
devices in your computer, including those devices on Plug and Play
busses such as ISAPNP, PCI, and PCMCIA (PC card) devices.
Enumeration occurs each time Windows starts and whenever Windows
receives notification that a change has occurred in the
computer's hardware configuration, such as when you remove a PCMCIA
- Q. What is Plug and Play?
A. Plug and Play is both a design philosophy and a set of personal
computer architecture specifications with the goal of making the
personal computer, add-in hardware devices, drivers, and the
operating system work together automatically without user
intervention. In order to achieve this goal, all the components
must be Plug and Play. The components of a Plug and Play system
Depending on whether any of these components are Plug and Play or
not, the level of ease of use and dynamic operation varies. At the
lowest level, where all three components are legacy, or non-Plug
and Play, the system lacks any dynamic operation and is difficult
to use since card jumpers and switches need to be manually set and
drivers manually loaded.
- A Plug and Play operating system
- A Plug and Play Basic Input Output System (BIOS)
- Plug and Play hardware devices with drivers
At the next level, when a Plug and Play operating system (such as
Windows) is used with legacy hardware, the system supports
dynamic operation of PCMCIA devices and is relatively easy to use.
Ease of use is enhanced during hardware setup by the Device Wizard
(which helps to detect, identify, and configure devices),
consistent user interface of device property sheets, and
availability of device information through the registry and Device
Manager. Additional ease of use is achieved due to automatic
loading of drivers using the Device Installer, and due to smart
software that reacts to configuration changes to give dynamic
hardware event messages.
At the highest level, where all three components are Plug and Play,
installing new devices is as easy as plugging them in and turning
on the computer. Hardware setup is completely silent and
transparent, and you do not need to modify expansion card jumper
settings, or even modify operating system configuration files.
Also, due to the Plug and Play BIOS, the system supports full
dynamic operation, including hot docking, APM 1.1 power management,
automatic configuration of boot devices, and programming of
- Q. There is a device installed in my computer for which I do not want
Windows to load drivers or allocate resources. How do I
A. You can use Device Manager to cause Windows not to load drivers
or allocate resources for a device. To do so, follow these steps:
- Click the Start button, point to Settings, and then click
- Double-click the System icon.
- On the Device Manager tab, click the device you want, and then
- On the General tab, click the Original Configuration (Current)
check box to clear it, and then click OK (Windows 95),
or click Disable in this hardware profile. (Windows 95 OEM Service Release 2 (OSR2) and Windows 98).
- Q. When I installed Windows on my laptop computer, it did not
detect or install support for my PCMCIA modem. Why?
A. Windows automatically identifies, configures, and installs Plug
and Play devices, including PCMCIA cards. This requires that 32-bit
PCMCIA support be installed, which is disabled by default. To
enable this feature, please see the "To enable 32-bit PC card
support" topic in Windows Help.
- Q. How can I tell if Windows recognizes my PCMCIA card correctly?
A. To determine whether a PCMCIA card is recognized correctly, use the
- Listen for the insertion tones (beeps) when you insert the card.
- Look for the PC card icon on the taskbar.
- Check the PC card icon in Control Panel.
NOTE: If the PC Card Wizard was not already invoked, it will start.
- Q. I installed Windows on my laptop computer, but Advanced Power
Management (APM) does not seem to be installed. What can I do?
A. To determine whether APM is installed, check to see if a Suspend
command appears on the Start menu. If not, check to see if a Power
icon appears in Control Panel. If there is a Power icon, APM is
installed. To make the Suspend command available on the Start menu,
double-click the Power icon in Control Panel, then click "Always
show Suspend command on Start menu." If APM still does not work,
follow these steps:
If APM is not installed, you must reinstall Windows to install
APM support. If APM is not automatically detected on your computer,
it is not guaranteed to work.
- Use the right mouse button to click My Computer, then click
Properties on the menu that appears.
- On the Device Manager tab, double-click System Devices.
- If Advanced Power Management is not listed under System Devices,
APM is not installed. Stop here.
- If Advanced Power Management is listed under System Devices,
click it, and then click Properties.
- On the Settings tab, click Enable Power Management if it is not
selected, and then click OK.
NOTE: Even if the Suspend command appears on the Start menu, you
may not have full APM support. Please contact your computer
manufacturer for details about your computer's APM implementation
if certain APM features do not work.
- Q. My computer uses a dual-port PCI E/IDE controller but the secondary
port is not displayed in Device Manager. Why?
A. By default, the secondary port is not displayed if no device is
attached to it. The secondary port may also not be displayed for
the following reasons:
- The controller has real-mode drivers loaded and they are
required in order to access the secondary port.
- The controller is not directly supported in Windows.
- The manufacturer or vendor has disabled the secondary port internally.
- Q. When I insert my laptop computer in its docking station, or remove
it from the docking station, Windows does not recognize the
A. Windows recognizes the docking state for some of the more
popular laptop computers equipped with a Plug and Play BIOS. If
Windows does not recognize the docking state for your computer,
you must manually establish docked and undocked profiles and choose
which profile you want to load during Windows startup.
Article ID: 133159 - Last Review: January 19, 2007 - Revision: 2.1
- Microsoft Windows Millennium Edition
- Microsoft Windows 98 Second Edition
- Microsoft Windows 98 Standard Edition
- Microsoft Windows 95
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