Editing Windows Driver Model (section)

== Device drivers for different Windows operating systems ==
The WDM framework was developed by Microsoft to simplify the communication between the operating system and drivers inside the kernel. In Windows operating systems, drivers are implemented as [[Dynamic Link Libraries]] .DLL or .SYS files. WDM compliant drivers must follow rules of design, initialisation, plug-and-play, power management and memory allocation. In practice WDM driver programmers reuse large pieces of code when building new [[Object-oriented programming|object-oriented]] drivers. This means that drivers in the WDM stack may contain residual functionality, which is not documented in specifications.<ref name="Penkler" /> Drivers that have passed the Microsoft quality test are digitally signed by Microsoft. The [[WHQL Testing|Microsoft Hardware Compatibility Tests]] and the Driver Development Kit include reliability and stress tests.<ref>{{Cite book|title=Service Availability: Third International Service Availability Symposium, ISAS 2006, Helsinki, Finland, May 15-16, 2006, Revised Selected Papers|editor1= Dave Penkler |editor2=Manfred Reitenspiess |editor3=Francis Tam |publisher=Springer Science & Business Media |year=2006|isbn=9783540687245|pages=132}}</ref>

A device driver that is not designed for a specific hardware component may allow another device to function. This is because the basic functionality of a hardware device class is similar. The functionality of the video card class, for example, allows the Microsoft Basic Display Adapter driver to work with a wide variety of video cards. However, installing the wrong driver for a device will mean that the full functionality of the device can not be used, and may result in poor performance and the destabilization of the Windows operating system. Hardware device vendors may release updated device drivers for particular Windows operating systems, to improve performance, add functionality or fix [[Software bug|bugs]]. If a device is not working as expected the latest device drivers should be downloaded from the vendor website and installed.<ref name=":2">{{Cite book|title=Microsoft Specialist Guide to Microsoft Windows 10 (Exam 70-697, Configuring Windows Devices)|author1=Byron Wright |author2=Leon Plesniarski |publisher=Cengage Learning |year=2016|isbn=9781285868578|pages=96}}</ref>

Device drivers are designed for particular Windows operating system versions, and device drivers for a previous version of Windows may not work correctly or at all with other versions. Because many device drivers run in kernel mode installing drivers for a previous operating system version may destabilise the Windows operating system. Migrating a computer to a higher version of a Windows operating system therefore requires that new device drivers are installed for all hardware components. Finding up to date device drivers and installing them for [[Windows 10]] has introduced complications into the migration process.<ref name=":2" />

Common device driver compatibility issues include: a [[32-bit]] device driver is required for a 32-bit Windows operating system, and a [[64-bit]] device driver is required for a 64-bit Windows operating system. 64-bit device drivers must be signed by Microsoft, because they run in kernel mode and have unrestricted access to the computer hardware. For operating systems prior to Windows 10 Microsoft allowed vendors to sign their 64-bit drivers themselves, assuming vendors had undertaken compatibility tests. However, Windows 10 64-bit drivers now need to be signed by Microsoft. Therefore, device vendors have to submit their drivers to Microsoft for testing and approval. The driver installation package includes all files in the .inf directory, and all files in the package need to be installed, otherwise the installation of the device driver may fail. For operating system versions before Windows 10 not all files necessary for the driver installation were included in the package, as this requirement was not consistently enforced. Some device driver installers have a user interface [[GUI]], often requiring user configuration input. The absence of a user interface does not mean that the installation of the device driver is not successful. Besides, Windows 10 device drivers are not allowed to include a user interface. The [[Network Driver Interface Specification]] (NDIS) 10.x is used for network devices by the Windows 10 operating system. Network device drivers for [[Windows XP]] use NDIS 5.x and may work with subsequent Windows operating systems, but for performance reasons network device drivers should implement NDIS 6.0 or higher.<ref name=":2" />