Hello everyone,

I have been working on a project to add IntelliMouse-style scroll wheel support to Windows 3.1 in 386 enhanced mode. The idea is to have a VxD (WHEELVXD.386) that hooks IRQ12 (or uses I/O trapping on port 0x60) to parse PS/2 packets, detect the wheel via the standard rate sequence (200 → 100 → 80 Hz), and accumulate wheel deltas. A companion patch to the DDK mouse driver (MOUSE.DRV) exports WheelSupported and GetWheelDelta that forward calls to the VxD.

What is working so far:
- The VxD compiles without errors (MASM 5.10B, link386, addhdr).
- Windows 3.1 boots normally with device=WHEELVXD.386 in SYSTEM.INI.
- MOUSE.DRV exports the two functions (GetProcAddress returns valid addresses).

The problem:
- Calling INT 2Fh, AX=1684h, BX=0xE5E5 returns ES:DI = 0 (NULL). The VxD API entry point is not found.
- Consequently, WheelSupported and GetWheelDelta always return 0.

What I have tried:
- Direct IRQ12 hooking (via VPICD_Virtualize_IRQ) – Windows boots but the entry point still not found.
- I/O trapping with Install_IO_Handler on port 0x60 – same result.
- Removing all memory allocation (_PageAllocate) to isolate the issue – still no entry point.
- Verified the device ID in Declare_Virtual_Device matches 0xE5E5.
- Verified the VxD is in SYSTEM directory and the .386 file passes addhdr.

My suspicion:
- The VxD may be failing initialization silently (e.g., _PageAllocate returns error, or I/O handler installation fails), causing Windows to load it but not register its device ID correctly.
- Or the device ID 0xE5E5 might conflict with something else, though I chose it arbitrarily.

What I am asking for:
If anyone here has experience with Windows 3.1 VxD development, I would be very grateful if you could take a look at the code and point out what I am missing or doing wrong. The full source code (including build scripts and test programs) is available on GitHub:

github.com/qv1145145/Windows-3.1-PS-2-Mouse-Wheel-Support/

Any insights, suggestions, or even a small fix would be highly appreciated. I am happy to provide additional details if needed.

Thank you in advance for your time and help!