WINUSB 1.0 — USB driver for DOS, Windows 1.0x/2.xx/3.xx and Windows 95/98/ME

WINUSB is a USB stack written from scratch for MS-DOS 5 / 6, Windows 1.0x, 2.x, 3.0, 3.1 / Windows for Workgroups 3.11 and Windows 95 / 98 / ME:

• Host controllers: UHCI, OHCI, EHCI (USB 2.0), xHCI (USB 3.x)
• Mass storage: Bulk-Only (BOT) and UAS (USB Attached SCSI; with streams on USB 3, without on USB 2), 4K-sector devices, write protection, media change
• HID: keyboard (LEDs, typematic, Pause / PrintScreen), mouse (5 buttons, wheel, horizontal wheel) and absolute pointers (USB tablets, touch screens, graphics tablets, the "usb-tablet" of virtual machines)
• PS/2 keyboard and mouse inside the driver: the mouse in IntelliMouse Explorer mode (wheel, buttons 4 and 5); on Windows 95/98/ME it replaces Windows' own PS/2 mouse driver; the PS/2 keyboard's LEDs follow the lock keys of the USB keyboards too
• Back / forward buttons (4th and 5th mouse buttons, as Alt+Left / Alt+Right) and autoscroll (click the wheel and move the mouse to scroll, with a scroll cursor) on all Windows versions (§3)
• Multi-partition USB disks: every partition (MBR, extended, GPT) gets its own letter; 4 letter slots by default, more when the disks plugged in at boot have more partitions
• Touchpads on every system (DOS, Windows 1.0x–3.11, 95/98/ME): USB and I2C precision touchpads (HID over I2C: ACPI PNP0C50 / ACPI0C50, Intel LPSS and AMD I2C controllers, the HID descriptor address from _DSM, the GpioInt interrupt line), PS/2 touchpads (Synaptics, ELAN) and SMBus touchpads (Synaptics InterTouch / RMI4, ELAN); two-finger scrolling (vertical and horizontal), tap to click, two-finger tap = right click, clickpads, TrackPoint (§4a)
• USB cameras (UVC 1.0–1.5; YUY2, NV12, Motion-JPEG; isochronous and bulk) and WINCAM.EXE: live picture, photos (BMP), video (AVI) (§5a)
• USB Audio 1.0 / 2.0 sound cards, headsets, DACs and USB MIDI output (through WINSOUND.DRV on Windows 3.0 MME / 3.1; §5)
• USB4 / Thunderbolt host support (§4b): host router / NHI driver, software connection manager for USB4 and Thunderbolt 1–3 devices, Intel firmware connection manager (ICM); NVMe disks behind PCIe tunnels (read / write, hot plug, drive letters) and the xHCI controllers of docks, USB3 tunnels (hubs and devices on USB4 links); PCIe hot plug under DOS (bus and BAR assignment)
• USB CD/DVD drives in DOS through MSCDEX (WINUCD.SYS) and on Windows 95/98/ME
• Dynamic drive letters, hot plug and safe removal
• USBTREE.EXE (Windows) and WININFO.EXE (DOS): detailed USB tree and descriptors
• DOS, Windows 1.0x / 2.x, Windows 3.0 Real Mode, Standard Mode and 386 Enhanced Mode (VxD)
• Windows 95 / 98 / ME: Plug and Play device driver (WINUSB.VXD, installed from INF files through Device Manager), USB devices in their own Device Manager classes (USB, Keyboard, Mouse, HID, sound, imaging, Disk drives), and the I/O Supervisor port driver WINUSB.PDR for the disks (32-bit drive letters) (§3b)

WINUSB is one of the four WINDRV packages, each in its own repository and usable alone or together with the others:

Package	What it drives
WINDISK	IDE, SATA AHCI and NVMe disks, IDE/AHCI CD/DVD drives, SD card readers and eMMC
WINUSB	USB host controllers and devices, PS/2 mouse and keyboard, touchpads, USB4 / Thunderbolt
WINAUDIO	HD Audio, AC'97 and the Intel audio DSP (SST / SOF), General MIDI synthesizer
WINUDF	the UDF file system (DVD, Blu-ray, packet-written CDs, UDF disks), read and write

---

Supported systems

System	WINUSB
MS-DOS 5.0 / 6.x	disks, keyboard, mouse (PS/2 path and INT 33h), touchpads, USB CD/DVD (MSCDEX), sound (AUDTEST /USB), USB4 / Thunderbolt (NVMe, docks)
Windows 1.0x	USB keyboard, disks (as letters), mouse (INT 33h) + wheel (cursor-key scrolling)
Windows 2.x (real mode)	USB keyboard, disks (as letters), mouse (INT 33h / "Microsoft Mouse") + wheel (cursor-key scrolling)
Windows/386 2.x	does not work (see "Known limitations")
Windows 3.0 Real Mode	keyboard, mouse, touchpads, disks, camera, beeps (WINBEEP.DRV)
Windows 3.0 Standard / 386 Enhanced Mode	everything (sound with the Multimedia Extensions)
Windows 3.1, WfW 3.11	everything
Windows 95 / 98 / ME	everything, as Plug and Play devices: WINUSB.VXD + the IOS port driver WINUSB.PDR (32-bit drive letters), PS/2 keyboard, mouse and touchpads (§3b)

Repository layout

bin/DOS     DOS: the driver, its 32-bit core, tools, installer and uninstaller (also all
            Windows 1.0x / 2.x need)
bin/WIN3X   Windows 3.0, 3.1 and Windows for Workgroups 3.11
bin/WIN9X   Windows 95, 98 and ME (Plug and Play drivers and their INF files: the folder
            to give to "Have Disk" / "Update Driver")
src         the source code (see "Building")

Files used by several systems are in each of their folders. The installer is run from bin\DOS; it takes the files of the other systems from the folders next to it, so the bin tree has to stay together (copy all of it to a floppy or a directory).

Folder	Files
bin/DOS	AUDTEST.EXE, DSKBENCH.EXE, INSTUSB.EXE, README.TXT, UNINUSB.EXE, WININFO.EXE, WINUCD.SYS, WINUCORE.BIN, WINUSB.SYS
bin/WIN3X	OEMSETUP.INF, USBTREE.EXE, WIN30FIX.COM, WINBEEP.DRV, WINCAM.EXE, WINGRP.EXE, WINMIX.EXE, WINMOUSE.DRV, WINSOUND.DRV, WINUSB.386, WINUSB.TXT, WINWHEEL.EXE
bin/WIN9X	USBTREE.EXE, WIN4G.VXD, WINCAM.EXE, WINDRVCI.DLL, WINGRP.EXE, WINKBD.INF, WINMIX.EXE, WINMOU.INF, WINMOUSE.DRV, WINSOUND.DRV, WINUSB.INF, WINUSB.PDR, WINUSB.TXT, WINUSB.VXD, WINUSBA.INF, WINUSBD.INF, WINUSBH.INF, WINUSBS.INF, WINUSBV.INF, WINWHEEL.EXE

1. Requirements

• Pentium or later processor (TSC), MS-DOS 5.0 / 6.x, HIMEM.SYS, PCI bus
• Windows (optional):
  • 3.0, 3.1, WfW 3.11: everything (sound on Windows 3.0 needs the Multimedia Extensions)
  • 2.x (real mode): USB keyboard and USB disks (the disks appear as drive letters in the MS-DOS Executive). For the mouse WINUSB provides the standard INT 33h DOS mouse interface: DOS programs using INT 33h and Windows set up with the "Microsoft Mouse" driver see the USB mouse; INT 33h survives into real-mode Windows. The wheel works too: Windows and programs written before the wheel know no scroll message, so every wheel notch is turned into cursor (up / down) keystrokes given to the keyboard controller; the MS-DOS Executive list and every program that reacts to the cursor keys scroll. DOS programs that read the wheel themselves get the INT 33h wheel API (CuteMouse, function 11h), which turns the key translation off for them.
  • 1.0x: USB keyboard, USB disks and the mouse wheel (cursor keys); the mouse with a driver that uses INT 33h
  • Windows/386 2.x: no USB service while it runs (V86 mode without VCPI)
  • 95, 98, ME: everything, as Plug and Play drivers (§3b)
• For a USB keyboard / mouse in DOS, Real and Standard Mode: an 8042-compatible keyboard controller

2. Files

File	Folder	Purpose
WINUSB.SYS	DOS	DOS block device driver (CONFIG.SYS)
WINUCORE.BIN	DOS	32-bit driver core (DOS / Standard Mode), in the directory of WINUSB.SYS
WINUCD.SYS	DOS	DOS CD-ROM device WINUCD01 for USB CD/DVD drives (with MSCDEX)
WININFO.EXE	DOS	status, tree, descriptors, safe removal, log
DSKBENCH.EXE	DOS	sequential read benchmark
AUDTEST.EXE	DOS	sound device list, test tone, WAV play / record, MIDI test (AUDTEST /USB)
INSTUSB.EXE	DOS	installer
UNINUSB.EXE	DOS	uninstaller
README.TXT	DOS	this text (code page 437)
WINUSB.386	WIN3X	Windows 386 Enhanced Mode VxD, in the directory of WINUSB.SYS (loaded automatically)
WINMOUSE.DRV	WIN3X, WIN9X	Windows mouse driver: USB + PS/2, wheel, back / forward buttons, tablets
WINWHEEL.EXE	WIN3X, WIN9X	passes the wheel / horizontal wheel to programs, autoscroll
USBTREE.EXE	WIN3X, WIN9X	USB tree, descriptors, disks, log, safe removal, report
WINCAM.EXE	WIN3X, WIN9X	USB camera picture, photos, video
WINSOUND.DRV	WIN3X, WIN9X	MMSYSTEM sound driver (wave, MIDI, aux) for USB Audio devices
WINMIX.EXE	WIN3X, WIN9X	volume levels / recording source
WINBEEP.DRV	WIN3X	Windows 3.0 SOUND driver: beeps and the PLAY / SOUND API in Real Mode too
WIN30FIX.COM	WIN3X	XMS fix for Windows 3.0 Standard Mode with more than 16 MB of memory
OEMSETUP.INF	WIN3X	for installing the mouse driver with Windows Setup
WINGRP.EXE	WIN3X, WIN9X	creates the Program Manager / Start menu group at the next start of Windows
WINUSB.TXT	WIN3X, WIN9X	this text for Notepad ("Read Me" item of the group)
WINUSB.VXD	WIN9X	Windows 95/98/ME Plug and Play VxD (from SYSTEM.INI at boot; DevLoader and USB enumerator)
WINUSB.PDR	WIN9X	I/O Supervisor port driver: USB disks, CD/DVD drives and NVMe (SYSTEM\IOSUBSYS)
WINUSB.INF	WIN9X	host controllers (UHCI / OHCI / EHCI / xHCI / USB4), hubs, other USB devices (Universal Serial Bus controllers)
WINKBD.INF	WIN9X	USB and PS/2 keyboards (Keyboard)
WINMOU.INF	WIN9X	USB and PS/2 mice and touchpads (Mouse)
WINUSBH.INF	WIN9X	tablets, touch screens, other HID devices (Human Interface Devices)
WINUSBA.INF	WIN9X	USB Audio 1.0 / 2.0, USB MIDI (Sound, video and game controllers)
WINUSBV.INF	WIN9X	USB Video Class cameras (Imaging devices)
WINUSBD.INF	WIN9X	USB disks (UAS, BOT) and NVMe namespaces behind tunnels (Disk drives, *IOS)
WINUSBS.INF	WIN9X	Thunderbolt 3 / USB4 NHI, Intel LPSS I2C (System devices)
WINDRVCI.DLL	WIN9X	Windows 95: icons of the USB, HID and Imaging classes (class installer)
WIN4G.VXD	WIN9X	moves PCI resources above 4 GB below 4 GB at boot (see "PCI resources above 4 GB")

3. Installation

Run the installer from DOS (not from inside Windows 3.x), from bin\DOS of this package. The default target is the Windows directory (found from WIN.COM on the PATH, or given with /W:; C:\WINDOWS otherwise); when the target is the Windows directory the generically named OEMSETUP.INF is not copied:

INSTUSB                      installs into the Windows directory (e.g. C:\WINDOWS)
INSTUSB D:\DRV\WIN /W:D:\WIN  another directory and Windows directory
INSTUSB /NOWIN               the DOS driver only (no mouse / wheel / sound settings)
INSTUSB /NOSOUND             WINSOUND.DRV (USB sound) is not installed
INSTUSB /O /R:4              with driver options (everything after /O goes to WINUSB.SYS)
INSTUSB /DOS                 MS-DOS 7 (Windows 95/98): adds WINUSB.SYS to CONFIG.SYS too

INSTUSB finds every Windows installation of the machine (1.0x to 3.11 and 95 / 98 / ME) and sets each up for its version (/W:dir selects one). It

• copies the files and adds DEVICE=C:\WINDOWS\WINUSB.SYS to CONFIG.SYS after the HIMEM.SYS / EMM386 lines and after WINDISK.SYS if present (in every block of a menu CONFIG.SYS that loads HIMEM),
• copies WINMOUSE.DRV to WINDOWS\SYSTEM and sets mouse.drv=winmouse.drv in SYSTEM.INI (the previous mouse driver is saved in the [WINUSB] section),
• adds WINWHEEL.EXE to the load= line of WIN.INI and the [WinWheel] settings,
• for USB sound copies WINSOUND.DRV to WINDOWS\SYSTEM and puts it into the wave=, midi= and aux= keys of the [drivers] section of SYSTEM.INI (a driver already there moves to the first free wave1= … key), and points and selects the "General MIDI" setup of the MIDI Mapper at the WIN synthesizer (WINAUDIO's synthesizer is preferred when it is installed). WINSOUND.DRV is shared with WINAUDIO and removed with the last of the two.
• on Windows 3.0 installs WINBEEP.DRV ([boot] sound.drv=winbeep.drv; the old one is kept in [WINSOUND] OldSound): Windows 3.0's MMSYSTEM.DLL cannot load in Real Mode, so beeps, MessageBeep and the PLAY / SOUND calls (SetVoiceNote …) are played by this driver on the MIDI synthesizer of the sound device; in Standard / Enhanced Mode system sounds go to MMSYSTEM (sndPlaySound).
• adds the WINUSB group (USB Devices, Camera, Volume Control, Disk Info, Read Me) to Program Manager on Windows 3.0 / 3.1 and to the Start menu on Windows 95/98/ME; installing again does not duplicate lines or group items,
• on Windows 1.0x / 2.x sets up only CONFIG.SYS and tells which mouse driver to use.

The original of every changed file is saved once with the .WNU extension (CONFIG.WNU, SYSTEM.WNU, WIN.WNU). Running it again is safe; the old options are kept unless /O is given.

Uninstall: C:\WINDOWS\UNINUSB removes the CONFIG.SYS line, restores the previous mouse driver, removes WINWHEEL from load= and the [WinWheel] / [WINUSB] sections, the group, WINMOUSE.DRV and the package files (no other file of the Windows directory is touched) (/K keeps the files, /W:dir names the Windows directory). WININFO / DSKBENCH stay when WINDISK is installed in the same directory.

Manual installation:

1. CONFIG.SYS (after WINDISK if that is used too):

   DEVICE=C:\DOS\HIMEM.SYS
   DEVICE=C:\WINDOWS\WINUSB.SYS
   DEVICE=C:\WINDOWS\WINUCD.SYS          (USB CD/DVD drives in DOS)
   

   AUTOEXEC.BAT for USB CD/DVD drives: C:\DOS\MSCDEX.EXE /D:WINUCD01
2. Mouse: Windows Setup → Mouse → Other mouse (requires disk from OEM) → bin\WIN3X, or copy WINMOUSE.DRV to C:\WINDOWS\SYSTEM and set mouse.drv=winmouse.drv in the [boot] section of SYSTEM.INI.
3. Wheel, WIN.INI:

   [windows]
   load=C:\WINDOWS\WINWHEEL.EXE
   
   [WinWheel]
   Lines=3
   Invert=0
   

[WinWheel] settings (WIN.INI):

Key	Default	Meaning
Lines	3	lines scrolled per wheel notch
Invert	0	1: reverse the wheel direction
XButtons	1	buttons 4 and 5 (back / forward) as Alt+Left / Alt+Right; 0: off
AutoScroll	1	a wheel click starts autoscroll in windows with a scroll bar
AutoScrollSpeed	100	autoscroll speed (percent, 10–1000)
NoAutoScroll	IE, Word, Excel, Mozilla, Opera window classes	window classes of programs that handle the wheel click themselves (comma separated)

Autoscroll: a short press of the wheel turns the pointer into a four-way scroll cursor that stays in place; the further the mouse moves away from that point, the faster the window scrolls in that direction (vertically and horizontally). Another click or a key ends it. When the wheel is held and dragged, scrolling ends with the release. In windows without a scroll bar and in the programs of NoAutoScroll the middle button goes to the program.

3b. Windows 95 / 98 / ME

On Windows 9x WINUSB is a Plug and Play driver; CONFIG.SYS gets no line (Windows ME has no CONFIG.SYS). device=winusb.vxd in SYSTEM.INI loads the VxD at boot: the USB host controllers start before the I/O Supervisor, so a Windows booted from a USB stick runs its boot disk on the 32-bit path too. Installation:

1. Run INSTUSB from bin\DOS (in DOS or in a DOS box). It recognizes Windows 9x, copies WINUSB.VXD, WIN4G.VXD, WINDRVCI.DLL, WINMOUSE.DRV, WINSOUND.DRV, WINWHEEL.EXE, USBTREE.EXE, WINCAM.EXE and WINMIX.EXE to WINDOWS\SYSTEM, WINUSB.PDR to WINDOWS\SYSTEM\IOSUBSYS and the INF files to WINDOWS\INF (without their CopyFiles lines: the files are in place already, so Windows does not ask for a disk for each), and sets mouse.drv=winmouse.drv, [drivers] wave= / midi=winsound.drv, device=win4g.vxd and device=winusb.vxd in SYSTEM.INI and load=winwheel.exe in WIN.INI. Files Windows keeps open (an older WINUSB.VXD, say) are replaced at the next boot through WININIT.INI.

2. Device Manager (Control Panel, System): select the USB controller.

   • Windows 95: Remove the "PCI Card" / "PCI Universal Serial Bus" item (Other devices) and Refresh: "New Hardware Found" comes up and "Windows default driver" (WINDRV from the INF database) is chosen. (Windows 95's "Change Driver" list has no USB class before the first installation.)
   • Windows 98 / ME: for the controller with Microsoft's driver under "Universal Serial Bus controllers" (or "PCI Universal Serial Bus" under "Other devices"): Properties, Driver, Update Driver, "Specify a location" / Have Disk, C:\WINDOWS\INF (or bin\WIN9X of this package). Windows 98 and ME find the full driver name ("WINUSB USB 3.x xHCI Host Controller" …) in the INF themselves.

   When the WINDRV driver is chosen, WINUSB.VXD loads and runs at once; a restart is asked for only when files Windows keeps open were replaced. A controller Windows has never seen before is offered the WINDRV driver at boot by itself. Device names are precise on Windows 95 too: the VxD writes "WINUSB USB 3.x xHCI Host Controller", "USB 2.0 EHCI", "USB 1.x UHCI / OHCI", "USB4 Host Interface", "USB4/Thunderbolt 3 (NHI)" and "NVMe Controller" into the devnode by the PCI class code; USB devices show their product names, disks appear as "USB 3.x UAS Disk" / "USB Mass Storage (BOT) Disk" / "NVMe Namespace Disk".

3. Once the VxD runs it creates a devnode for every USB device it finds; Windows installs them silently or with "New Hardware Found" and puts each into its class: keyboards under "Keyboard", mice under "Mouse", tablets and other HID devices under "Human Interface Devices", sound cards and MIDI under "Sound, video and game controllers", cameras under "Imaging devices", disks under "Disk drives" (with letters), hubs and the rest under "Universal Serial Bus controllers". The classes Windows 95 lacks are installed by the INF, their icons come from WINDRVCI.DLL.

4. PS/2 mouse: once a WINUSB controller runs, the PS/2 mouse devnode installed with Windows' own driver (VMOUSE + MSMOUSE.VXD) is turned into a WINUSB one ("WINUSB PS/2 Mouse (IntelliMouse Explorer, 5 buttons)"); from the next boot on WINUSB.VXD drives the mouse (until then it takes it over when WINMOUSE.DRV starts). The wheel, the back / forward buttons and autoscroll work with the PS/2 mouse too, and Synaptics / ELAN touchpads switch to their own protocols (§4a). /NOPS2 (the Options value of the controller devnode) turns this off.

How it works:

• WINUSB.VXD is loaded from SYSTEM.INI at boot (init order 15000000h, before the I/O Supervisor) and starts the USB host controllers at once; without that line CONFIGMG loads it dynamically. Either way CONFIGMG calls it for every WINDRV controller with DevLoader=WINUSB.VXD (PNP_NEW_DEVNODE); the VxD registers with CM_Register_Device_Driver, takes the resources at CONFIG_START, starts the controller, and lets go of it at CONFIG_STOP / REMOVE (Disable / Remove in Device Manager work; after suspend it is started again at CONFIG_APM). Several controllers run in one core and are started together (UHCI / OHCI next to EHCI, xHCI port routing).
• The VxD is the enumerator of the controller devnode (CM_Register_Enumerator): USB devices become child devnodes with the id WINUSB\VID_xxxx&PID_yyyy\<controller><port path> (hardware / compatible ids WINUSB\HID, WINUSB\HUB, WINUSB\STORAGE, WINUSB\AUDIO, WINUSB\VIDEO, WINUSB\DEVICE); the devnode of a removed device is deleted with CM_Remove_SubTree (at appy time), and a device plugged into the same port again gets the same devnode (and letter).
• Disks: WINUSBD.INF gives the disk devnodes DevLoader=*IOS and PortDriver=WINUSB.PDR. The IOS loads WINUSB.PDR (DRP / ILB registration, AEP_INITIALIZE per devnode, AEP_DEVICE_INQUIRY, AEP_CONFIG_DCB); the port driver passes read / write / verify requests to the core through the service table of WINUSB.VXD (device 3D34h) and completes them at once. Partitions are recognized by the disk TSD and the IOS gives the letters; there is no "MS-DOS compatibility mode" / RMM.
• Booting from USB: a USB disk the BIOS offers through INT 13h (boot disk 80h included) is found by WINUSB (size and the BPBs of the DOS drives); once the controller runs, WINUSB does its INT 13h transfers, the I/O Supervisor finds the disk at WINUSB.PDR and moves C: to the 32-bit path (Windows 95 and ME, tried with QEMU xHCI / UHCI). The boot disk is not removed at shutdown; other USB disks stay removable. When WINUSB is installed while Windows runs, the boot disk moves to the 32-bit path at the next boot.
• Shutdown and MS-DOS mode: when Windows shuts down or restarts in MS-DOS mode the USB controllers are handed back to the BIOS (EHCI / xHCI ownership with the SMI on ownership change, the BIOS register state of UHCI / OHCI restored), so a USB keyboard works in DOS again without a new POST. A Windows booted from a USB stick cannot reach its disk through the BIOS on the "It's now safe..." screen and in "Restart in MS-DOS mode" ("Restart" is fine).
• CD/DVD: USB CD/DVD drives (BOT / UAS, SCSI device type 5) get a SCSI bus DCB from WINUSB.PDR; CDFS reads them in 32 bits, disc change and Eject work (Windows 95/98/ME). In DOS they work through WINUCD.SYS and MSCDEX.
• Removable disks without FAT partitions (a UDF-formatted stick, say) are reported as removable drives, so they get a letter on Windows 98 / ME (for WINUDF).
• NVMe: the NVMe controllers of the mainboard run with WINDISK's driver on Windows 9x; WINUSB offers only the NVMe disks behind a Thunderbolt / USB4 tunnel, as WINUSB\NVME\... devnodes.
• Options: the INF writes an empty Options value into the software key of the controller devnode; WINUSB.SYS options such as /D /POLL /NOTB … go there (Regedit: HKLM\System\CurrentControlSet\Services\Class\USB\000n\Options) and are read at the first CONFIG_START. When it is empty, Options= of the [WINUSB] section of SYSTEM.INI is used — at boot only: VMM does not offer that service after Windows has started, so a controller installed while Windows runs gets the SYSTEM.INI options at the next boot. With /D the VxD and the PDR log to port 0E9h (QEMU -debugcon) and COM1 if there is one.
• The DOS driver on Windows 9x: with INSTUSB /DOS, WINUSB.SYS goes into CONFIG.SYS too (keyboard, mouse and disks in Windows 95/98 "DOS mode"). On MS-DOS 7 the DOS driver gives no drive letters by default (/DOSDISK makes it do so) and does not load the VxD through SIS when Windows starts: Windows' Plug and Play VxD and port driver take the disks, the DOS core lets go of the hardware.
• Thunderbolt / USB4: when the NHI devnode is given to WINUSB.VXD the tunnels are set up as in DOS; the xHCI / NVMe functions behind a tunnel are driven by WINUSB directly (the PCI enumerator of Windows 9x knows nothing of PCIe hot plug; these devices do not appear in Device Manager separately).
• Limits: USB sound / MIDI and cameras are used through WINSOUND.DRV and WINCAM as on DOS / 3.x (no DirectSound / VFW interface). In QEMU, DOS boxes close ("must be run in MS-DOS mode") while SeaBIOS uses a USB keyboard or mouse it saw at boot: SeaBIOS's USB HID code in the timer interrupt cannot run in V86 mode. That is specific to QEMU.

Options

Option	Meaning
/R:n	drive letters reserved for USB disks (20 at most). By default at least 4, more when the removable disks plugged in at boot have more FAT partitions (plus one spare); WINUSB then waits for the USB devices at boot
/WIN	USB only in Windows 386 Enhanced Mode (off in DOS)
/NOMSC	no mass storage
/NOHID	no keyboard / mouse
/NOKBC	no 8042 injection in DOS
/NOVXD	do not load the VxD in Enhanced Mode
/V, /D, /COM1	log options
/S	the driver log goes to the screen too (diagnosis on machines without a serial port)
/POLL	no controller interrupts, polling only (for IRQ problems)
/NORELOC	do not move PCI resources from above 4 GB at boot
/ALL4G	move every device below 4 GB at boot, not only the WINDRV devices
/NOPS2	leave the PS/2 mouse to DOS / the BIOS and Windows' own driver
/NOXHCI, /NOEHCI, /NOOHCI, /NOUHCI	leave controllers of that kind to the BIOS
/NOROUTE	do not route the EHCI ports to xHCI on Intel 7 / 8 / 9 series
/NOI2C	no I2C touchpads / touch screens (§4a)
/NOTP	PS/2 touchpads stay in their mouse mode, no SMBus (§4a)
/NOSMB	touchpads on PS/2 only, not on SMBus (§4a)
/NOTB	no USB4 / Thunderbolt host support (§4b)
/NOTBPCIE	no PCIe tunnels (no NVMe and dock xHCI, USB3 only)
/NOTBUSB	no USB3 tunnels on USB4 links
/PCIHP	watch every hot-plug capable PCIe port, Thunderbolt or not (ExpressCard, PCIe slots)
/NVME, /NONVME	NVMe controllers behind tunnels: also take over the one the BIOS started / never use them
/DOSDISK	MS-DOS 7: drive letters from the DOS driver too

4. How it works

• DOS and Standard Mode: the USB stack is polled from the timer (INT 08h) and DOS idle (INT 28h) interrupts, only at safe moments (DOS not inside a function, no BIOS disk call in progress). USB interrupts that come at an unsafe moment are masked in the PIC and served at the next safe poll.
• Keyboard: in DOS / Standard Mode the keystrokes are injected into the 8042 with command D2h (every program sees a PS/2 keyboard); in Enhanced Mode with VKD_Force_Keys.
• Mouse: in DOS, once a DOS mouse driver opens the BIOS PS/2 interface, IntelliMouse 4-byte packets are injected with D3h. In Standard Mode WINMOUSE.DRV reads the motion from the driver's mailbox; in Enhanced Mode the VxD calls WINMOUSE.DRV directly. A real PS/2 mouse works next to the USB mouse in every mode (with the wheel in Standard Mode).
• Tablets / touch screens: devices with absolute X / Y in their HID report descriptor (Generic Desktop Pointer / Mouse and Digitizer collections: pen, touch screen, digitizer; tip switch = left, barrel / eraser = right) move the Windows pointer straight to the screen position (WINMOUSE.DRV absolute mode; Enhanced and Standard Mode). In DOS the absolute position becomes relative PS/2 motion.
• Letters: /R:n slots are reserved (at least 4 by default, more with the partitions found at boot); a device is matched by serial number / VID / PID / partition and gets the same letter when it comes back. Removal is reported to DOS as a media change. On multi-partition disks (MBR primary and extended partitions, GPT) every partition gets its own slot. On Windows 95/98/ME Windows gives the letters; all partitions appear.
• PS/2 mouse: WINUSB drives the auxiliary port of the 8042 itself (in DOS through the BIOS's INT 15h C2h interface, in Windows 3.x Enhanced Mode and Windows 9x with IRQ 12): IntelliMouse Explorer mode (4-byte packets, wheel, buttons 4 and 5). On Windows 9x the VxD answers the INT 15h C2h calls so that Windows' mouse drivers do not program the mouse again through the BIOS.
• xHCI: on Intel 7 / 8 series the EHCI ports are routed to xHCI; burst / streams at USB 3 speed. EHCI: low / full-speed devices go to the companion UHCI / OHCI or to the hub's TT.
• Several keyboards: NumLock / CapsLock / ScrollLock LEDs are kept the same on all USB keyboards and the PS/2 keyboard; modifier keys (Shift, Ctrl, Alt) are shared (Shift held on one keyboard is not released by a Shift released on another).

4a. Touchpads

Notebook touchpads come on three kinds of connection; WINUSB knows all three and feeds the fingers to the same gesture engine. It works on every system: DOS (with /USB), every mode of Windows 1.0x–3.11 and Windows 95/98/ME.

Gesture	Event
one finger	pointer (8 counts per millimetre; Windows' mouse speed and acceleration apply)
two fingers up / down	wheel (one notch per 2.5 mm; fingers down → page down)
two fingers left / right	horizontal wheel
short tap	left click; two fingers: right click; three fingers: middle click
touchpad button / clickpad	left click; right click while two fingers touch
TrackPoint	pointer; scrolling while the middle button is held, a middle click on its own

• USB and I2C precision touchpads (Windows Precision Touchpad) are recognized by the "Touch Pad" collection of their HID report descriptor and switched from mouse mode to touchpad mode (Input Mode = 3, surface and button reporting on). Contacts marked as a palm (Confidence = 0) are ignored; touchpads that send one report per contact (hybrid reporting) are supported; the touch time comes from the touchpad's own time stamp (Scan Time).

• I2C (HID over I2C): the devices are read from the ACPI tables (DSDT and SSDTs): for every device whose _HID / _CID is PNP0C50 or ACPI0C50, its I2cSerialBus addresses (alternatives in several resource templates included), the I2C controller that resource names, the HID descriptor address function 1 of _DSM returns for the HID over I2C UUID (a constant, a Name or a field; a helper method call is resolved too) and its GpioInt line. Controllers: Intel LPSS (as PCI functions, or the "ACPI mode" seen only in ACPI: INT33C2/3, INT3432/3, 80860F41, 808622C1, INT3446/7, 80865AAC...; powered up through PSAT as its _PS0 does) and AMD (AMD0010, AMDI0010, AMDI0510; always ACPI devices). When the GpioInt pad can be read (Intel GPIO communities, Bay Trail / Cherry Trail, AMD AMDI0030) and the device really drives the line at its reset, the input register is read only while the line is asserted; otherwise it is polled (8 ms in Enhanced Mode and Windows 9x, at the timer rate in DOS and Standard Mode). Without an ACPI device the usual touchpad addresses and descriptor registers are tried on the LPSS PCI functions. I2C touch screens and mice work the same way (absolute / relative pointers).

• PS/2 touchpads (ACPI ids SYN..., ETD..., LEN0... with the compatible id PNP0F13): the device on the 8042's auxiliary port is queried and a known touchpad is switched to its absolute protocol:

  • Synaptics: identify (E8 00 ×4, E9 → 47h), "sliced" queries (capabilities, model, resolution, maximum / minimum coordinates), absolute mode with W (F3 14h), advanced gesture mode (position of the second finger), clickpads, middle button, TrackPoint packets of the pass-through port (W = 3). The finger count comes from W (0: two, 1: three fingers).
  • ELAN: signature (E6 ×3, E9 → 3Ch 03h C8h), hardware versions 2, 3 and 4 from the firmware version; register writes through F8 custom commands; the multi-finger head / motion / status packets of version 4, the two-finger packets of versions 2 and 3, CRC packets, clickpads, TrackPoint packets.

  In Windows 3.x Enhanced Mode and Windows 95/98/ME the VxD takes IRQ 12 itself (as for the PS/2 mouse). In DOS (/USB) WINUSB.SYS collects the touchpad's bytes on IRQ 12, the core decodes them and hands the motion as ready PS/2 packets to the callback the DOS mouse driver registered with the BIOS (INT 15h C207h); INT 33h and WINMOUSE.DRV in Standard Mode get the motion through the mailbox (WINMOUSE then leaves the 8042 alone). The DOS driver's mouse calls through the BIOS (reset, rate...) reach the touchpad; once they are over, the touchpad is programmed again, and also when only broken packets come (someone reset it behind our back). The touchpad goes back to its mouse mode when Windows starts. ALPS and old touchpads (the first forms of the absolute protocols) stay in mouse mode.

• SMBus touchpads: Synaptics InterTouch (capability bit) and ELAN touchpads with an SMBus side (bus field of the resolution query) are found through PS/2 and moved to the SMBus host of Intel chipsets (i801, 00:1F.3 / 00:1F.4, 32-byte block buffer); the PS/2 side goes quiet. Synaptics RMI4 (address 2Ch): version byte (FDh), the 8-entry address map, from the page description table F01 (device control, interrupt status), F11 or F12 (2D sensor; F12's register descriptors, sensor size) and F30 / F3A (buttons); the interrupt status is polled. ELAN (address 15h): hello packet, enable, absolute mode, range and resolution; reports are read when the touchpad's Host Notify arrives (the host's slave status register is polled). A touchpad that does not answer on SMBus stays on PS/2; /NOSMB never tries SMBus. SMBus is used in Windows 3.x Enhanced Mode and Windows 95/98/ME; in DOS and Standard Mode the touchpad stays on the interrupt-driven PS/2 path (SMBus could only be polled at the timer rate there).

• A touchpad in its own mouse mode has no two-finger scrolling, which is why WINUSB uses the touchpad modes. /NOTP leaves PS/2 and SMBus touchpads in mouse mode, /NOI2C turns the I2C support off.

4b. USB4 / Thunderbolt

WINUSB finds the NHI (Native Host Interface) of a Thunderbolt / USB4 host controller (PCI class 08/80 and the known device ids on Intel; class 0C/03/40 on USB4, AMD and ASMedia included) and drives its ring-0 control channel by polling. There are two connection managers; the host says at start which one applies:

• Firmware CM (ICM): Falcon / Alpine / Titan / Maple Ridge, and Ice Lake+ controllers in "Thunderbolt firmware" mode. The driver tells the firmware "driver ready" and approves the devices that connect (security level None or User Authorization); the firmware sets up the tunnels, this driver starts the PCIe functions.
• Software CM: USB4 hosts (Intel Ice Lake+ in "native" / "software" mode, AMD, ASMedia) and Thunderbolt 1–3 on Apple machines. The driver enumerates the host router and the routers plugged in (USB4 or Thunderbolt) itself, powers them up (USB4 ROUTER_CS, Intel link controller), writes the hop tables and sets up the tunnels: a PCIe tunnel for every device (the device's PCIe up adapter <-> a free PCIe down adapter of the host) and, on USB4 links, a USB3 tunnel (bandwidth requested from the host adapter). Daisy chains are followed up to a depth of 6. Tunnels the BIOS set up at boot (booting from a Thunderbolt disk) are left alone.

Once a tunnel is up, the device's PCIe functions appear behind the hot-plug capable PCIe port of the host. DOS has no PCIe hot-plug service, so WINUSB does it itself: from the bus range and memory window the BIOS reserved for that port it assigns windows to the bridges (the dock's PCIe switch) and BARs to the end functions, then starts the NVMe controllers (nvme.c, the same driver as in WINDISK; namespaces get letters in the /R:n slots) and the xHCI controllers of docks. When a device is pulled out its functions are removed and the letters freed. On Thunderbolt 3 docks USB is the dock's xHCI over PCIe; on USB4 devices the USB3 tunnel comes out as a hub on a port of the host's own xHCI.

BIOS settings: Thunderbolt / USB4 on; security level No Security or User Authorization (Secure Connect needs a stored key, this driver stores none); "Thunderbolt PCIe reservation" / "PCIe hot-plug resource reservation" (bus and memory reservation) on — if no window is reserved the driver logs it and the device cannot start. Firmware or software mode does not matter.

Not supported: DisplayPort tunnels (display output), host-to-host (XDomain) links, NVM upgrades, link bonding (one lane is used; still enough for NVMe on 20 / 40 Gb/s links).

WININFO /B lists the host, routers, adapters (with lane state), tunnels and the devices the firmware CM reports. /D gives a detailed log. This code follows the hardware specifications (USB4, Intel NHI / ICM); QEMU has no Thunderbolt emulation, so only the PCIe hot-plug / NVMe path (q35 pcie-root-port + device_add nvme, /PCIHP) was verified in the emulator — for the first tries on real Thunderbolt / USB4 hardware take a log with /D /S.

Real hardware notes (Intel / AMD / others)

• BIOS handoff: before the driver starts, all USB controllers are taken from the BIOS (legacy USB, SMM): USBLEGSUP on UHCI, ownership change on OHCI, the BIOS / OS semaphore on EHCI / xHCI, and the SMIs are turned off. When the BIOS does not let go, the controller is taken anyway. On Intel 7 / 8 / 9 series the EHCI → xHCI port routing is done after that. When Windows exits or restarts in MS-DOS mode the controllers are handed back.
• xHCI: the register space is mapped with the extended capabilities (Intel: 8000h). After an Intel reset 1 ms is waited, CNR is waited for at start, scratchpad buffers are allocated. Etron EJ168 / EJ188 and Fresco Logic FL1000 / FL1009 have broken streams, so UAS disks use Bulk-Only there. Renesas uPD720201 / 202 cards without a firmware ROM need a firmware loader; the log says so.
• EHCI: the AMD SB600 / SB700 (A12) and VIA VT6212 fixes are applied. The AMD-8111 EHCI (broken) is not used; its ports work through OHCI. Intel's integrated hub (RMH) and the AMD / VIA companion OHCI / UHCI controllers are supported.
• Interrupts: an IRQ is used only when no other PCI device uses it and the ELCR shows it level triggered (PCI). On shared lines (common on real boards, e.g. the same IRQ as the GPU, NVMe or network card) the controller is polled and its INTx output turned off, so another device's interrupt cannot turn into a storm. The interrupt output is turned on after the real-mode handler is installed (at the first poll). When a line keeps firing with interrupts that are not ours, the driver drops it and polls.
• Troubleshooting: for a hang at boot, see the last line with /S; then narrow the controller or the step down with /NOXHCI, /NOEHCI, /NOROUTE, /POLL.

5. USB Audio and MIDI

• Devices: USB Audio Class 1.0 (older USB 1.1 sound cards, headsets) and 2.0 (USB 2.0 audio interfaces, DACs); isochronous transfers on UHCI, OHCI, EHCI (high speed: iTD; full-speed devices behind hubs: siTD split transactions) and xHCI. Every audio function becomes a sound device.
• Format: the device's best setting is chosen (2 channels, 16 / 24 / 32 bit, preferably 48 kHz, else 44.1 / 96 kHz …); programs can use any PCM format (8 / 16 / 24 / 32 bit, float, 1–8 channels, 2–192 kHz); conversion and mixing of up to 16 streams are done in software (polyphase sinc sample rate converter).
• Synchronization: asynchronous devices are followed through their feedback endpoint; adaptive and synchronous devices are fed at the nominal rate.
• Volume: with a Feature Unit the master and recording volume are set in the device (dB scale, mute included), otherwise in software. With a Selector Unit the recording source (mic / line / CD / aux) can be chosen.
• Recording: USB microphones and the inputs of sound cards.
• USB MIDI: devices with a MIDI Streaming interface (USB-MIDI cables, keyboards, modules) appear as a separate MIDI output in Windows (short messages and SysEx).
• Synthesizer: the 32-voice General MIDI synthesizer of WINAUDIO plays on USB sound devices too ("WIN USB GM Synth").
• Hot plug: programs using a removed device do not hang (their buffers complete), the device stays in the list as "unplugged"; the same device plugged in again gets the same device number and settings. MMSYSTEM reads the number of devices only at start, so WINSOUND.DRV keeps room for up to 2 USB sound devices plugged in while Windows runs ("WIN USB Audio 1/2"); a device plugged in later is bound to those. WINMIX updates its list live.
• DOS: AUDTEST /USB plays and records in DOS too (WINSOUND.DRV uses the same path in Standard Mode). In Standard Mode and DOS packets are scheduled 150 ms ahead, in Enhanced Mode 40 ms.

5a. USB cameras and WINCAM

• Devices: USB Video Class 1.0–1.5 cameras (web cameras, notebook cameras, capture devices); formats YUY2, NV12 (uncompressed) and Motion-JPEG; isochronous (USB 1.1 / 2.0 / 3.x, high-bandwidth endpoints included) and bulk transfers. Frame size and rate come from the device's descriptors and are agreed with probe / commit. Frames up to 640×480 YUY2 (larger sizes with MJPEG, e.g. 1280×720) are kept.
• Frames are collected in two buffers; incomplete / broken frames (lost packets, JPEG without EOI) are dropped. Programs fetch the newest frame in pieces through the INT 2Fh API (WINF_CAM_*).
• WINCAM.EXE (Windows 3.0 Real / Standard / Enhanced, 3.1, 95/98/ME): camera and picture size selection, live picture (scaled to the window; with a 6×6×6 palette on 256-colour displays, dithered to the VGA colours on 16-colour displays), Photo (24-bit BMP), Record (AVI: MJPG losslessly from a Motion-JPEG camera, with the missing Huffman tables added; uncompressed 24-bit frames from YUY2 / NV12), Folder... (directory of the files, WIN.INI [WINCAM] Folder=). File names PHOTOnnn.BMP, VIDEOnnn.AVI. In Real Mode YUY2 frames are processed line by line when memory is short. Command line: WINCAM [/MODE n] [/SNAP] [/REC seconds] [/QUIT].
• WININFO /C (DOS): cameras and picture sizes; WININFO /C n file writes a frame to a file.

6. Tools

WININFO            status, disks, letters, USB tree
WININFO /T         USB tree with all ports
WININFO /B         Thunderbolt / USB4: host, routers, adapters, tunnels (§4b)
WININFO /D id      device descriptors (device / config / interface / endpoint / SS companion /
                   UAS pipe / IAD / HID / BOS)
WININFO /E id      safe removal (SMARTDRV and the DOS buffers are flushed first)
WININFO /LU        WINUSB event log
WININFO /P         partitions and file systems of the disks
WININFO /C [n file]  USB cameras; with n a frame to a file
DSKBENCH E: /M:32        read from drive E:
DSKBENCH /U:0 /M:64 /N   raw read from WINUSB disk 0

USBTREE: on the left a lined tree of controllers / ports / devices (coloured marks by device type) and a "Disks and partitions" item, on the right details and descriptors; Refresh, Safe remove, Log, Save (full report; with the file dialog when COMMDLG is there), Auto refresh (every 2 seconds, on change). With WINDISK loaded the disk view shows its disks, CD/DVD drives and SD cards too, with partitions and file systems.

PCI resources above 4 GB

With "Above 4G Decoding" enabled in the BIOS setup, the firmware may place the registers of some devices (64-bit BARs) and bridge windows above 4 GB, where 32-bit DOS and Windows cannot reach them. At boot, before Windows and its drivers look at the machine, the DOS driver (WINUSB.SYS; whichever WINDRV DOS driver loads first does it for all) moves those resources of the devices WINDRV drives into free PCI space below 4 GB: USB controllers (UHCI / OHCI / EHCI / xHCI / USB4), audio (HD Audio, AC'97, Intel audio DSP), disk controllers (IDE, SATA, RAID, NVMe), SD controllers, Intel LPSS I2C and Thunderbolt NHI. When such a device sits behind a bridge with a prefetchable window above 4 GB, the whole tree below that bridge (nested bridges and the BARs behind them, largest first) is placed again. Graphics cards and all other devices stay where the firmware put them (the log says pci 01:00.0 BAR above 4G left in place (not a WINDRV device; /ALL4G moves it)), so "Above 4G" only affects the drivers' own devices. /ALL4G moves every device and bridge window (a large BAR that does not fit is shrunk with Resizable BAR), /NORELOC turns the pass off (a device's BAR is then moved alone when its driver starts it). The free space is computed from TOLUD..PCIEXBAR on Intel Core chipsets, TOP_MEM..FEC00000 on AMD, and every BAR, window and ACPI MCFG range in the system. Each move is logged as pci 00:14.0 BAR 4000000000 -> 9f000000 (64K).

On Windows 95 / 98 / ME the same is done by WIN4G.VXD: the INF files (and the installer) copy it to SYSTEM\ and add device=win4g.vxd to the [386Enh] section of SYSTEM.INI. This small static VxD does the move at every boot, before the Plug and Play PCI enumeration and before all device drivers (Sys_Critical_Init), so the devices come below 4 GB on Windows ME too, which has no CONFIG.SYS driver. One restart is needed after the first installation. All4G=1 in the [WIN4G] section of SYSTEM.INI moves all devices (like /ALL4G); Debug=1 (port E9h) or Debug=COM1 log what it does.

Architecture

            DOS / Real / Standard Mode                386 Enhanced Mode
   +-----------------------------------+   +-----------------------------------+
   | DOS, programs, Windows (real /    |   | Windows VMs (system VM + DOS)     |
   | standard mode, DOSX)              |   |                                   |
   +-----------------+-----------------+   +-----------------+-----------------+
                     | block / character device requests, INT 2Fh API
   +-----------------v-----------------+   +-----------------v-----------------+
   | WINUSB.SYS     (16-bit DOS driver)   |-->| WINUSB.386     (VxD, ring 0)          |
   |  - drive letters, INT 2Fh API     |   |  - the same 32-bit core code      |
   |  - 8042 injection (kbd / mouse)   |   |  - VPICD, VKD, WINMOUSE, VMM      |
   +-----------------+-----------------+   +-----------------------------------+
                     | switch to protected mode (directly in real mode, VCPI under EMM386)
   +-----------------v-----------------+
   | WINUCORE.BIN   (32-bit core in an   |
   | XMS block, with paging)           |
   +-----------------------------------+

• The DOS driver is loaded by CONFIG.SYS, puts the 32-bit core into XMS memory and switches the processor to protected mode for a moment on every request.
• The VxD is loaded automatically when Windows 386 Enhanced Mode starts (INT 2Fh / 1605h); SYSTEM.INI needs no line. The DOS core lets go of the hardware, the VxD (compiled from the same sources) takes it over, and the DOS core takes it back when Windows exits.
• In DOS, Real and Standard Mode the core is polled from the timer (INT 08h) and DOS idle (INT 28h) interrupts, only at safe moments (DOS not inside a function, no BIOS disk call in progress). In Enhanced Mode the VxD runs every 10 ms.
• Windows 95 / 98 / ME use the Plug and Play VxD built from the same core instead.
• An exception in the core writes WINUSB CORE EXCEPTION ... on a red background in the first screen line and stops; a photo of that line is enough to locate the fault.
• API: INT 2Fh, AH=D4h (see src/inc/winapi.h).

Building

Needed: Open Watcom v2 (wcc, wcc386, wrc, wlink), NASM and Python 3.

export WATCOM=/opt/watcom          # the Open Watcom installation
cd src
./build.sh                         # objects in ../obj, the files sorted into ../bin/DOS,
                                   # ../bin/WIN3X and ../bin/WIN9X (src/bin-layout.txt)

src/buildtools holds the build helpers: fixvxd.py (turns the LE file of wlink into the form the Windows 3.1 VMM expects), oslayout.py (sorts the output by system), genserv.py (VxD service numbers from the DDK INC files; src/inc/vxdsvc.inc comes ready made), genicons.py (program icons) and mkdisk.py (disk images for tests).

Source files and documents are stored with CRLF line ends; .gitattributes keeps them so.

Source tree

Directory	Contents
src/core	the 32-bit core (all systems): PCI, ACPI, block layer, UHCI / OHCI / EHCI / xHCI, hubs, HID, precision touchpads (ptp.c), PS/2 touchpads (ps2tp.c, 8042: kbc.c), SMBus touchpads (smbtp.c), HID over I2C (i2c.c, DesignWare I2C dwi2c.c, GPIO gpio.c), mass storage, USB Audio, UVC, sound engine and synthesizer, NVMe, USB4 / Thunderbolt (nhi.c, tbt.c, icm.c), PCIe hot plug
src/inc	shared headers (winapi.h: API and control block), VxD service numbers
src/dos	DOS: WINUSB.SYS (NASM), the DOS platform layer of the core, WINUCD.SYS, WIN30FIX.COM
src/vxd	Windows 3.x Enhanced Mode and Windows 95/98/ME: the VxD platform layer and entries, PS/2 mouse (ps2.c), Plug and Play, WIN4G.VXD
src/pdr	Windows 95/98/ME: the I/O Supervisor port driver WINUSB.PDR
src/inf	Windows 95/98/ME: the INF files
src/win	Windows (16-bit, 3.x and 9x): WINMOUSE.DRV, WINWHEEL, USBTREE, WINCAM, WINSOUND.DRV, WINBEEP.DRV, WINMIX, WINGRP, WINDRVCI.DLL
src/tools	DOS programs: installer / uninstaller (winsetup.c), WININFO, DSKBENCH, AUDTEST; generators of cursors and GPIO tables
src/tests	host tests of the touchpad code (host/tp), the usb-redir device emulator (qemu/uredir.py)
src/buildtools	build helpers (Python)

Tests

src/tests/host/tp/run.sh (a second or two) runs the touchpad code on Linux against device models: Synaptics (absolute mode, W, advanced gesture mode, clickpad, TrackPoint) and ELAN v4 PS/2 touchpads; RMI4 (F01, F12 register descriptors, F3A) and ELAN behind an i801 SMBus model; a HID over I2C touchpad with _DSM and GpioInt in ACPI; the ACPI scan (constant and named _DSM results, the Switch form, alternative addresses). Each checks the pointer, two-finger scrolling, taps and buttons. src/tests/qemu/uredir.py emulates USB devices QEMU lacks (UVC cameras, a precision touchpad) through usb-redir.

QEMU + SeaBIOS (with your own DOS 6.22 / Windows disk images) was used to verify: UHCI / OHCI / EHCI (+ companion) / xHCI enumeration, BOT and UAS read / write, hot plug and letter reassignment, the USB keyboard in DOS / Standard / Enhanced Mode, the USB mouse + wheel (Standard and Enhanced), the PS/2 mouse, WININFO, USBTREE (safe removal included), DSKBENCH, working together with WINDISK, returning from Windows to DOS, INSTUSB / UNINUSB (SYSTEM.INI and WIN.INI byte for byte the same as the originals after uninstalling), stability over many boots in a row, the USB tablet (Standard and Enhanced Mode), USB Audio 1.0 playback and the synthesizer on UHCI / OHCI / xHCI in DOS and Windows (QEMU usb-audio, output recorded with -audiodev wav and analysed), hot removal / plugging, installation / removal together with WINAUDIO; USBTREE, WINMIX, WINWHEEL and WINBEEP (beep frequencies measured) in Windows 3.0 Real / Standard / Enhanced Mode; LED and modifier sync on three keyboards (PS/2 + 2 USB), motion of three mice; re-plugging a USB stick with and without safe removal (same letter, data intact); a USB sound device plugged in while Windows runs; 11 picture modes of an emulated UVC camera (full and high-speed isochronous, bulk; YUY2 160×120 … 640×480, MJPEG 320×240 … 1280×720, NV12) in DOS and with WINCAM in Windows 3.0 Real / Enhanced and 3.1 as photos and video; motion, taps, two-finger scrolling and the button on an emulated USB touchpad (one and several contacts per report; DOS and Windows 3.1); the USB keyboard on Windows 1.01, 2.03 and 2.11; Windows 95 RTM, 98 FE and ME with the INF files (xHCI, USB mouse / keyboard / tablet / sound / disk at boot and hot plugged, the PS/2 mouse taken over, class icons, booting from a USB stick, USB CD/DVD).

Known limitations

• Real hardware: the drivers were verified in QEMU and by code review. The fixes for particular Intel / AMD hardware were written from the Linux drivers and the datasheets.
• Windows/386 2.x switches the processor to V86 mode without offering VCPI; while it runs the 32-bit core cannot be entered and the driver serves no requests. The real-mode Windows 2.x (WIN86.COM / WIN.COM) works.
• DOS file systems: DOS 5 / 6 read only FAT12 / FAT16 (2 GB per partition at most); FAT32, NTFS, exFAT ... partitions get no drive letter.
• SeaBIOS (QEMU only): when SeaBIOS uses a USB keyboard or mouse at boot, its USB polling in SMM can stop the machine while Windows 2.x starts, and DOS boxes of Windows 95/98/ME close. Real BIOSes hand the controllers over properly (BIOS / OS semaphore, SMIs off).
• WfW 3.11 was not tried on real hardware.
• In DOS / Standard Mode the polling runs at the timer rate (about 18 Hz); mouse motion comes in coarser steps than in Enhanced Mode. A USB mouse in DOS needs a DOS mouse driver that works in PS/2 (INT 15h C2h) mode, or WINUSB's own INT 33h service.
• The wheel and buttons 4 / 5 of a PS/2 mouse depend on its IntelliMouse (Explorer) mode; other mice work with 3 buttons.
• USB disks the BIOS offers through INT 13h must not be used through the BIOS once WINUSB has taken them over; DOS sees them under WINUSB's letters.
• Without an 8042, the USB keyboard / mouse does not work in DOS / Standard Mode.
• Intel 7 series (Panther Point) xHCI: some boards may hang on restart after Ctrl+Alt+Del (a known chipset erratum); use /NOROUTE then.
• USB4 / Thunderbolt: the NHI, the connection managers and the tunnels were not tried on real hardware yet (QEMU does not emulate them); the PCIe hot plug + NVMe path was verified in QEMU (§4b). No DisplayPort tunnels and no host-to-host links. xHCI controllers the firmware offers on PCI work.
• USB Audio: QEMU offers only a full-speed UAC1 playback device, so USB Audio 2.0, high-speed (EHCI iTD) and behind-a-hub (siTD) transfers, recording and feedback were not tried on a real device. Devices with implicit feedback are fed at the nominal rate.
• Touchpads: the USB path was tested with an emulated touchpad in QEMU; the I2C, PS/2 (Synaptics, ELAN) and SMBus (RMI4, ELAN) paths against device models on Linux; not tried on a real notebook (QEMU does not emulate these touchpads). The SMBus of AMD chipsets (no Host Notify) is not used: those touchpads work on PS/2. Touchpads that give a plain Interrupt () instead of GpioInt are polled. The scroll direction is fixed (fingers down → page down). ALPS and old touchpads that have no touchpad mode work as ordinary mice. In DOS a touchpad works with a DOS mouse driver that uses the BIOS's INT 15h C2h interface (CTMOUSE, MOUSE.COM) or with WINUSB's INT 33h service.
• Cameras: not tried with a real camera (an emulated camera through usb-redir). The frame rate depends on the processor: MJPEG decoding and colour conversion run in 16-bit Windows code. Sound (the camera's microphone) works separately as USB Audio and is not recorded into the AVI. H.264 cameras and uncompressed sizes above 640×480 are not supported; in Windows 3.0 Real Mode 640×480 NV12 does not fit into memory.
• Windows 95 / 98 / ME: USB sound / MIDI and cameras only through WINSOUND.DRV and WINCAM (no DirectSound / VFW). A Windows booted from a USB stick cannot reach that disk through the BIOS after shutdown ("It's now safe..." screen, "Restart in MS-DOS mode").

Version history

1.0 (5 October 2026) — first release.

1.0 update (14 October 2026):

• Windows 95 / 98 / ME: a separate INF and class for every device kind (USB controllers, HID, sound, imaging, disks, system devices), type and speed in the device names (UHCI / OHCI / EHCI / xHCI / USB4, USB 1.1 / 2.0 / 3.x hubs, USB Audio 1.0 / 2.0), icons of the classes Windows 95 lacks (WINDRVCI.DLL), the IOS port driver WINUSB.PDR, booting from USB.
• PS/2 keyboard and mouse inside the driver (Windows' PS/2 mouse driver disabled, LEDs follow the USB lock keys), back / forward buttons, autoscroll with a wheel click; all partitions of USB disks, 4 letter slots by default, more with the partitions found at boot.
• Touchpads on every system: HID over I2C from ACPI (PNP0C50 / ACPI0C50, _DSM descriptor address, GpioInt, Intel LPSS ACPI mode and AMD I2C controllers), PS/2 Synaptics and ELAN touchpads (absolute protocols, clickpads, TrackPoint; in DOS too), Synaptics InterTouch (RMI4) and ELAN on SMBus; /NOTP, /NOSMB.
• USB CD/DVD drives in DOS (WINUCD.SYS, MSCDEX device WINUCD01); USB sticks without FAT partitions get a letter on Windows 98 / ME as removable drives.
• The USB controllers are handed back to the BIOS when Windows shuts down and restarts in MS-DOS mode (EHCI / xHCI ownership SMI, the BIOS state of UHCI / OHCI restored): the USB keyboard works in DOS without a new POST.
• PCI resources above 4 GB: the boot-time move applies only to WINDRV's devices (/ALL4G for all), WIN4G.VXD on Windows 9x.
• Windows 95 stability fixes: the DDB reference of the port driver (fatal exception 0E, Explorer / MSGSRV32 closing), the SYSTEM.INI service when installing while Windows runs.
• Installer: Start menu groups on Windows 95/98/ME, "Read Me" items, no duplicate entries when installing again; the package is split into bin/DOS, bin/WIN3X and bin/WIN9X.