This is a High Definition Audio aka Azalia codec and controller driver for retro Windows OSes. It supports the motherboard onboard audio for Intel 915 and later chipsets as well as other manufacturers that conform to the HD Audio standard.

It is designed for all versions of Windows with Windows Driver Model (WDM) support which is Windows 98(se)/Me/2000/XP, but only Windows 98 SE and ME are officially supported. The driver may load on Windows 98 First Edition but this is not supported due to known issues with sample rate and but depth conversion not working. Microsoft doesn't recommend the use of WDM audio drivers for this version of Windows.

As Windows 2000/XP already has official HD Audio support through the KB888111 HDA Bus driver update, these versions of Windows will be supported but are not the intended primary target.

Current status of this driver: known to function well in VMware, VirtualBox, Intel, Nvidia, AMD & VIA chipset HD Audio controllers with Realtek and VIA codecs; IDT, Analog Devices, and Cirrus Logic codecs are not well supported yet. Further testing is needed to improve support on all real hardware.

This driver is dependent on the BIOS Pin Configuration defaults for selecting a sensible combination of outputs and there are no overrides yet for buggy BIOSes. You may experience garbled or glitchy audio, possible horrible screeching and popping noises or static, or complete silence, as well as possible hard freezes when the driver is loaded or unloaded.

If you want to use this software in some kind of business critical production application, I would highly recommend using a Sound Blaster Live, CMI8738 or any $2 USB Audio dongle instead. (Seriously, almost all of the cheapest USB Audio 1.0 class adapters work perfectly in 98se/Me.)

Windows 9x may need to be patched to function at all on modern hardware and > 512mb of RAM even when virtualized. For Intel 12th gen and newer this is Mandatory. See JHRobotics' Patcher9x project which now includes Sweetlow's patch for memory resource conflict issues. Or for a prepatched solution, try Windows 98 QuickInstall from Oerg866.

• Install HDA.inf with Device Manager on the HD Audio Controller device.
  • On Windows 98se/Me the device is listed in "Other Devices" as "PCI Card" with class code 0403 (you can run hwinfo /ui to see the vendor /device info on unknown devices).
  • On Windows 2000/XP if you have the official KB888111 update installed, the audio controller will be listed in the "System Devices" section as "Microsoft UAA Bus Device" or similar. Do not install on the HD Audio Codec device (this will have a device ID string that starts with "HDAUDIO") as this will not function.
• If you get a dialog box saying "A file being copied is older than the file currently in use" for ksuser.dll and stream.sys, Always keep the newer file.
• After first installation, wait a few minutes to see if the speaker icon appears in the taskbar (the WDM audio components are installing and loading in the background). You must then restart for audio to work. If the Volume Control still does not appear after a restart, open the Multimedia control panel, click to select the "Show volume control on the taskbar" check box, then click OK and restart the computer again. If the WDM components will not install, try plugging in a USB audio device or see the workaround in issue #62 .

It is recommended but not strictly necessary to install DirectX 8.1 or newer after installing this driver as it contains some improvements to the kernel streaming components. You may also wish to install the WDM Audio Update from Microsoft, which are packages Q242937 and Q269601.

For best sound quality: go to the Multimedia control panel, Click the Advanced Properties button for the Playback device, go to the Performance tab and set Audio Acceleration to Standard (one notch to the left of Full) and Sample Rate Conversion Quality to Best (all the way to the right).

To allow playback of Redbook CD Audio, Digital CD Audio must be enabled:

• On Windows 98SE: go to the Multimedia control panel, the CD Music tab, and check the box for "Enable digital CD audio for this CD-ROM Device"
• On Windows Me/2000/XP: Go to the properties of your CD-ROM drive in Device Manager, the Properties tab, and check the box for "Enable digital CD audio for this CD-ROM Device"

• Only supports 16-bit stereo audio at 22-48khz sample rates (formats up to 96khz 32-bit could technically be added but 9x doesn't make the best choices about resampling)
• Playback only, recording is not supported
• Single audio stream, no hardware mixing
• Audio latency is ~40 ms at best. This is a kernel limit
• Volume control is only implemented for the main mix output
• Jack retasking is not supported, all jacks will be set as outputs if they can be. (Try all outputs, the audio output may only play through the Surround output on your motherboard.)
• Analog CD audio is not mixed into the audio output. Digital Audio Extraction is supported. Enable this as described above.
• DOS Sound Blaster emulation is normally provided by Microsoft's WDM emulator SBEMUL.SYS which only supports 8-bit stereo digital sound and General MIDI but does not emulate OPL. DOSBox can be used to run games with OPL emulation, and there is a patched version of SBEMUL available from SweetLow which will support 16-bit digital sound (high DMA the same as low DMA). The Alpha version of VDMSOUND for Windows 9x also works if you can get it set up.
• May Freeze, crash, fail to start or outputs horrible noises on some real hardware. No guarantees it will work on whatever laptop you may have. There are 22 years of HD Audio hardware out there and it's difficult to prove compatibility.

Source Code from Microsoft's driver samples

and BleskOS used under MIT license.

Code from FreeBSD adapted under BSD license, is credited at the top of the relevant files.

See also Dogbert's open source CMI 8738 driver.

For build instructions, see the file Building.md

The release build of the driver is in the buildfre\i386 folder, the debug build is in buildchk\i386.

• Find and install Sysinternals Debug View. A version that works on Win98 is here https://www.digiater.nl/openvms/decus/vmslt00a/nt/dbgview.htm
• Install the debug version of my driver by using the HDA.sys which is in the objchk\i386 folder. you can just copy this into C:\Windows\System32\Drivers if the driver was already installed
• Disable the HD audio controller device in Device Manager
• Restart
• Open DebugView
• Enable the HD audio controller device
• Watch the debug messages come in, they should explain why the driver is failing to start
• Save the log file from Debug View and post it to an issue or discussion thread here.

Testing and feedback from anyone who can run this driver on real hardware with a kernel debugger installed will be appreciated.

Pull requests or issues may be submitted at the project's GitHub page. Please only send pull requests for code that has been built and tested. We reserve the right to review, rework, or reject any and all pull requests.

Though the vast majority of the code in this project is human written, Generative AI (Large Language Models) have been used for research and debugging help, and writing small amounts of the code (C++ class and interface definitions, some memory safety fixes, one refactoring attempt with Copilot that ended in me manually fixing everything anyway).

I do not intend to make this a completely "Vibe Coded" project; all bugs are the fault and responsibility of the humans that submit the code so if you open a pull request, please prove that you understand what you're adding.

This software is supplied under the MIT License with NO WARRANTY, express or implied. See the MIT LICENSE file for more information. For support, please file an issue on Github or refer to the complaints department of the Sirius Cybernetics Corporation.