http://www.microsoft.com/TechNet/boes/bo/winntas/technote/mscompt.htm (PC Press Internet CD, 03/1996)
| Updated: March 13,1996 |  Go To TechNet Home Page |
ABSTRACT: This document presents information about Windows NT hardware compatibility. Key topics include definitions of terms, advice on minimizing compatibility problems with new hardware, locations of updated drivers and the most recent compatibility lists, and the impact of compatibility on support. Support professionals will find useful troubleshooting information, and a description of the compatibility testing processes.
Introduction
General Compatibility Information
Troubleshooting
The Testing Process
Glossary
Conclusion
People planning Windows NT deployment often ask what simple things they can do to make the process successful. The most beneficial step you can take is running Windows NT on compatible hardware. This document explains what "compatibility" means, how Microsoft evaluates it, and how it impacts you.
Hardware compatibility is a broad topic, and different people may wish to focus on different parts of this document. Everyone should read "General Compatibility Information," and if you make hardware purchasing decisions, be sure to read the subtopic titled "Compatibility and Usability." If you troubleshoot Windows NT, read the "Troubleshooting" section. If you're interested in background information about how and why Microsoft tests hardware, read "The Testing Process." A glossary at the end defines important terms and acronyms.
This section presents general information about hardware compatibility that most people will find useful, such as how Microsoft evaluates compatibility, how compatibility affects Windows NT technical support, and where you can find the most up-to-date compatibility lists and device drivers.
A specific hardware model is compatible with Windows NT if a Windows NT device driver exists that was designed to interact with that hardware model, and Windows NT and the device driver interoperate with the hardware in a stable manner.
Microsoft evaluates hardware compatibility using the Windows NT hardware compatibility tests (HCTs). These tests run on Windows NT and test the interaction between device drivers and hardware. These tests issue the full range of commands available to applications and operating system software, and they stress hardware beyond the level of most real-world situations. For information on the test process, see the section below titled "The Testing Process."
The hardware compatibility list (HCL) supplied with the Windows NT product lists each hardware model that had passed the HCTs when Windows NT was released. Microsoft releases an updated HCL quarterly. For more information on obtaining an updated HCL, see the topic below titled "Driver And HCL Updates."
The current Windows NT 3.51 HCL is organized around the following hardware categories:
Within each category, the HCL lists products alphabetically by manufacturer name, then by official model name and/or number. Remember that the official name is sometimes different from the common name, so some products may not be listed where you expect them. For example, "HP LaserJet 4" comes before "HP LaserJet III."
A model's entry in the HCL may be followed by one or more footnote references. These footnotes document additional setup instructions and known compatibility issues.
Many Windows NT support contacts result from people ignoring the HCL, or assuming that entries on the HCL imply support for other, unlisted hardware. The HCL is a precise list of supported hardware models: if the a particular model is not on the HCL then that model is not supported. A hardware model is supported if it is listed on the HCL, and you are using a Microsoft-supplied driver to control that hardware.
The following examples illustrate correct HCL interpretation:
People sometimes request a list of the hardware that failed the HCTs. If Microsoft made such a list available, OEMs and IHVs whose hardware failed would risk losing sales to competitors whose hardware passed the HCTs, and OEMs and IHVs would be reluctant to test their hardware. Also, the situation would strain relations between Microsoft and hardware manufacturers, which would hinder attempts to investigate and fix interoperability problems. Rather than focus on the small percentage of hardware that fails the HCTs, Microsoft provides a list of the large majority that pass the HCTs. If you want to avoid hardware that failed the HCTs, choose your hardware from the HCL.
People also request lists of hardware that is currently being tested and drivers that are currently being developed. If Microsoft made such a list available, OEMs and IHVs would risk losing sales to competitors whose products passed the tests more quickly. Again, releasing such a list would produce negative incentives for hardware manufacturers to test their products and to work with Microsoft to ensure compatibility. If you want to know whether a hardware product is currently in testing, or a driver is in development, ask the OEM or IHV.
This section explains how unsupported hardware affects the support you receive from the Windows NT support group at Microsoft. Key points include the meaning of "supported" and "unsupported," basic troubleshooting you should receive for unsupported hardware, and the reasons for restricting the support options that are available for unsupported hardware.
A hardware model is "supported" if it is listed on the HCL and you are using a Microsoft-supplied driver to control that hardware. The term "unsupported" does not imply anything about the relative quality of hardware or of third-party drivers. Many unsupported systems and devices work correctly with Windows NT. However, the Windows NT support staff at Microsoft will not offer a full range of support services for problems that are specific to unsupported hardware or drivers.
The support engineer determines whether the problem you describe might be related to the unsupported hardware. If so, the engineer sets your expectations that if basic troubleshooting confirms this possibility, then the problem is subject to support restrictions. Having set your expectations, the engineer will try to exceed them by finding a solution.
It does not matter whether the hardware is supported or not if any of the following are true:
If this initial troubleshooting does not identify the problem, and the problem appears to be specific to unsupported hardware, then the support engineer will finish collecting hardware information from you, so that other engineers can correlate that information if future problem reports match yours. Also, the engineer will decide, on a case-by-case basis, what support options to offer. These options might include:
Microsoft may not offer further technical support, because problems that are specific to unsupported hardware consume support resources that could be used more productively.
The HCTs test the interoperability of the operating system, the drivers and the hardware. However, a model's usability may involve factors beyond compatibility, such as exact feature sets and performance relative to other models. Consider the following before purchasing hardware for use with Windows NT:
There are three main categories of device drivers: those supplied with the Windows NT product, those available in the Windows NT Driver Library, and unsupported, third-party drivers. These drivers have different locations and different support policies.
The following table outlines locations of the Windows NT Driver Library (WNTDL) and the current Hardware Compatibility List (HCL):
|
Information Source |
WNTDL location: |
HCL location: |
|---|---|---|
|
Windows NT disks and CD-ROM. |
Not Available |
Hardcopy supplied with boxed product, updates not available |
|
Windows NT CD-ROM. |
\DRVLIB subdirectory. |
Hardcopy supplied with boxed product, updates not available |
|
TechNet |
Supplemental CD: Drivers and Patches (Disk 2). See the file: \SOFTLIB\ WNTDL.TXT . |
Navigate to Enterprise Systems, Windows NT Workstation, Technical Notes |
|
Microsoft Developer Network (MSDN-II) CD-ROM |
Windows NT Workstation CD-ROM, \DRVLIB subdirectory. |
Navigate to Knowledge Base and Bug Lists, Windows NT Kbase, Hardware Related Issues |
|
Internet (Connect via anonymous FTP to ftp.microsoft.com) |
Consult INDEX.TXT in the \SOFTLIB directory to find specific driver file names. Files are located in the MSLFILES subdirectory. |
Consult INDEX.TXT in the SOFTLIB directory to find current HCL file name. File is located in the MSLFILES subdirectory. |
|
World-Wide Web |
Navigate to http://www.microsoft.com, then to Support, BackOffice, Windows NT Server and Workstation, Software Library. |
Navigate to http://www.microsoft.com, then to Support, BackOffice, Windows NT Server and Workstation, Software Library, Miscellaneous Files. |
|
Microsoft Network (MSN) |
Navigate to Categories, Computers and Software, Software, Operating Systems, MS Windows NT Workstation Forum, MS Windows NT Workstation Support Desktop, MS Windows NT Server and Workstation Software Library. |
Navigate to Categories, Computers and Software, Software, Operating Systems, MS Windows NT Workstation Forum, MS Windows NT Workstation Support Desktop, MS Windows NT Server and Workstation Software Library, Miscellaneous Files. |
|
CompuServe |
GO MSL, then search for WNTDL to view the whole WNTDL list or another key word to view specific files. |
GO WINNT, then search Library 1 for Windows NT Hardware Compatibility List. |
|
Microsoft Download Service (MSDL) 206-936-MSDL, 8-1-N, 2400-28.8k baud. |
From the main menu, press F for File index. Select L to list the WNTDL files or E to examine a specific file. |
From the main menu, press F for File index. Search for Windows NT Hardware Compatibility List. |
|
Microsoft Online |
Search for WNTDL in the Software Library database. |
Search for Windows NT Hardware Compatibility List in the Software Library Database. |
This section discusses troubleshooting for hardware-related problems. These include true compatibility problems, related issues such as driver installation and hardware-specific problems unrelated to compatibility, and the effects of operating system updates on compatibility.
This discussion covers the two classes of "true" hardware compatibility problems:
If your problem does not match either of these, then continue to the "Other Hardware Problems," below.
A hardware manufacturer may choose not to write a Windows NT driver for new hardware. This is often the case if the new hardware's target market has little overlap with the Windows NT target market. For example, Windows NT is not a popular PC game platform, so joystick manufacturers have not written drivers for Windows NT.
If your device model is not on the HCL and does not emulate a device on the HCL, then Microsoft does not have a driver that is designed to support your model. The IHV may have a driver which Microsoft has not yet tested, but otherwise the device is not supported.
Windows NT runs correctly on most of the Intel x86, DEC Alpha, MIPS, and PReP-compliant PowerPC systems, even if they are not listed on the HCL. However, if you encounter problems using an unsupported system Microsoft may not be able to provide a solution. In addition, Windows NT has not been ported to some platforms, such as the Motorola 68000-series processors and PowerPC-based systems that are not PReP-compliant, such as the PowerPC Macintosh systems.
If there is no driver for your hardware, can should request future drivers from both the manufacturer and Microsoft. Although most device drivers originate from IHVs, Microsoft writes most printer drivers, and Microsoft may write other drivers if support for a device significantly impacts Windows NT sales.
These include any hardware-specific problems that affect multiple units of the same model, and are not attributable to hardware or software misconfiguration, hardware damage or defect, or software corruption. These problems may be caused by hardware or software design flaws, or by an ambiguous specification.
If you encounter interoperability problems that are specific to supported hardware, contact Microsoft. If the problem is specific to unsupported hardware then Microsoft may be able to provide basic troubleshooting, and the manufacturer may be able to help as well.
Despite efforts to ensure the accuracy of the HCL, a model might appear on the HCL when it should not. If you notice HCL errors, including typographic errors, please report them to Microsoft by sending e-mail to the alias, NTHCTEXT@MICROSOFT.COM.
This discussion presents hardware-specific problems that are not hardware compatibility problems, as well as device driver installation problems.
Most hardware-specific problems are not compatibility problems. Instead, they result from hardware or software misconfiguration, or from hardware damage or defect, or from driver corruption or manual editing of the Windows NT registry.
You should suspect that the problem is not related to hardware compatibility if the problem is specific to one hardware unit, and other units of the same make and model are functioning correctly. If one unit is failing while the others work correctly, the focus of your troubleshooting on differences between the failing unit and the working ones. Swapping hardware is often a good test, and comparing software configurations is also helpful.
Although true hardware compatibility problems affect multiple units of the same make and model, not all problems that affect multiple units are hardware compatibility problems. For example, if you receive a shipment of adapters which are all pre-configured for a particular IO base address, and the Windows NT driver defaults to a different base address, and the driver cannot identify or change the hardware configuration, then the driver and hardware will not work together. The problem will affect all of the adapters, but it is not a compatibility problem.
Drivers from the WNTDL may encounter the following installation problems:
If your device is not listed in a setup dialog, but the model is listed on the HCL, then you may have overlooked its entry in the setup dialog. Remember that the lists contain official, trademarked model names, which may be different from common model names.
Otherwise, if the driver is available in the \DRVLIB directory of your Windows NT CD-ROM, choose the option titled "<Other> Requires disk from manufacturer" and then direct the setup program to the appropriate subdirectory inside the \DRVLIB directory.
If the driver is not available in the \DRVLIB directory, or you are installing Windows NT from floppy disks:
Also, your model may emulate another model, in which case you should choose the emulated model in the setup dialog. For example, several supported network adapters emulate the Novell/Eagle Technology NE2000 adapter and use that driver. Footnotes in the HCL identify these supported emulations.
Upgrading Windows NT from one version to another, or installing service packs, can affect hardware compatibility. This typically affects devices more than systems.
Operating system updates rarely introduce problems for supported, uniprocessor, Intel x86-based systems. However, there is considerable variability in symmetric multiprocessing systems and in non-Intel systems. Microsoft requires that OEMs send these systems to Microsoft for testing, and Microsoft ensures that these systems are retested with operating system updates.
If an IHV creates a new device that requires a completely new device driver, the driver developer often designs the driver for the next release of Windows NT, rather than for the current release. New drivers can take months to develop and test, and designing drivers for the next release of Windows NT lets the new driver take advantage of feature enhancements and bug fixes that have occurred since the last release. However, if the IHV releases a new model in a model line that already has a driver, then the IHV often updates the current-version driver and makes that updated driver available. Such drivers will run on the current Windows NT release, but it may require the most recent service pack.
Note
Completely new drivers are rarely backdated to work with earlier versions of the operating system. For example, a driver written for Windows NT 3.51 is unlikely to work with Windows NT 3.5 or 3.1. If you need support for that hardware on systems currently running Windows NT 3.5 or 3.1, you will usually need to upgrade Windows NT.
Some people may be interested in the Windows NT compatibility testing process itself. For those people, this section discusses general topics such as driver development and testing motivations, testing time frames, and test logistics, as well as topics specific to the System HCTs, such as the difference between mandatory and optional HCTs.
Much of the testing process information is relevant to both system and devices. This includes topics such as what motivates driver development, who runs the HCTs, and how long testing takes. This section also describes the logistics of compatibility testing, which affect hardware compatibility with other operating systems as well as Windows NT.
Most of the time, customers make IHVs and OEMs aware of their compatibility needs and the manufacturers respond by developing drivers or testing systems. In addition, Microsoft lobbies IHVs and OEMs on behalf of customers who request support for their hardware.
Drivers for adapters and devices are usually a collaborative project between an IHV and Microsoft. The degree of participation by each party varies, and sometimes the IHV or Microsoft writes a driver without the other's help. Microsoft provides technical support for any driver that ships in Windows NT, or is available on the WNTDL.
OEMs frequently run the HCTs at their sites on Intel-based uniprocessor systems, and send the encrypted test results to Microsoft for confirmation. Roughly 70% of computer systems are tested this way. In the other 30% of cases, including all symmetric multiprocessor systems and all non-Intel based systems, the manufacturer sends hardware to Microsoft, and the Windows NT HCT team runs the tests and sends results to the manufacturer. All device testing occurs at Microsoft.
Hardware sent to Microsoft often remains at Microsoft. This hardware is used for testing the current version of Windows NT, and for investigating problem reports. Also, the HCT team uses this hardware to test future versions of Windows NT.
Several factors affect the length of time between the release of new hardware and its appearance on the HCL.
New systems in existing system model lines are easier to test than completely new model lines or completely new platforms. For example, testing new Intel-based, EISA-bus systems is relatively quick, because the tests already exist. However, between the releases of Windows NT 3.5 and 3.51, testing new PowerPC systems and PCMCIA-capable systems took longer because of the overhead of creating tests for these newly-supported technologies.
Similarly, device testing is usually faster when an IHV releases a new model in an existing, supported line than when an IHV releases a completely new model line.
If an OEM submits passing test results for a new model in a currently-supported line, the OEM will generally receive a customer-ready confirmation letter from the HCT team at Microsoft within three weeks. If the OEM sends the new system to Microsoft, it may take slightly longer because of shipping and setup time. If an IHV creates a new model line, and they make Windows NT driver development a high priority, the new driver may be available within a month of the adapter/device release.
The flexibility and variety of today's hardware creates compatibility testing challenges faced by all operating system vendors. This discussion describes the challenges and how Microsoft meets them.
Many systems and devices can be configured in different ways, and each configuration could, theoretically, introduce a compatibility problem. Microsoft, OEMs, and IHVs meet this challenge by testing several configurations of each system and device, emphasizing the most common configurations.
Also, the variety of hardware combinations is staggering. For example, at the time of this writing Windows NT 3.51 supports 112 different SCSI host adapters, 103 SCSI tape units, 52 SCSI CD-ROM drives, and 21 SCSI hard disks. There are over 12.5 million combinations of these four devices alone, without considering the devices' individual configurations or firmware revisions, or other potentially relevant variables, such as in which of the 3400 supported systems the SCSI devices might be installed.
OEMs, IHVs, and Microsoft maximize coverage by testing the most commonly-sold combinations. Also, when an OEM sends a system to Microsoft, the Windows NT HCT team tests that system with a variety of devices. Also, Microsoft tests each SCSI peripheral with the most common SCSI host adapters, and tests each host adapter with the most common SCSI peripherals.
Some parts of the System HCT are mandatory, other parts are optional.
The mandatory tests exercise the minimum hardware required to run Windows NT, and the optional tests exercise optional hardware. This lets OEMs run the HCTs on systems that do not include built-in, optional hardware. Also, it lets OEMs focus on functionality that their customers request. For example, if an OEM markets a system as a file and print server, and expects few customers to use multimedia hardware on these systems, the OEM can choose to skip the optional multimedia HCT. The OEM has this option even if the optional hardware is built into the system.
Mandatory tests include:
Optional tests include:
If you intend to purchase systems which include optional hardware that you intend to use with Windows NT, you may wish to confirm that the optional hardware is on the HCL. Otherwise, that hardware may not have been tested.
People too often overlook hardware compatibility when they plan Windows NT rollouts, when they purchase hardware, and when they contact Microsoft for technical support. Understanding compatibility testing can help make your rollouts easier and your troubleshooting less frustrating and more productive.
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