VxDs are Windows Virtual Device Drivers.  A VxD runs at CPU privilege
level 0 and thus has access to protected-mode CPU operations.

The following list provides the VxD ID numbers that can be used in
INT 2fH 1684H (get device entry address) calls.  Documentation on the API
services provided by VxDs can be hard to find (some info can be gleaned
from DDK source code files).  In most cases, a fn number is passed in
AX and most VxDs support fn 0000H to mean "get installed state/query
version".

0000H (Undef)    Can be used if VxD does not provide an API

0001H (VMM)      Virtual Machine Manager
0002H (Debug)    Win386 Debug Device

0003H (VPICD)    Virtual PIC (Programmable Interrupt Controller) Device
0004H (VMAD)     Virtual DMA (direct memory access) Device
0005H (VTD)      Virtual Timer Device
0006H (V86MMGR)  Virtual-86 Mode Memory Manager Device
0007H (PageSwap) Demand Paging Swap Device services
0008H (Parity)   handles Parity errors
0009H (Reboot)   handles virtual reboots
000aH (VDD)      Virtual Display Device
000bH (VSD)      Virtual Sound Device
000cH (VMD)      Virtual Mouse Device
000dH (VKD)      Virtual Keyboard Device
000eH (VCD)      Virtual COMM Device
000fH (VPD)      Virtual Printer Device

0010H (BlockDev) formerly Virtual Hard Disk Device (VHD)
0011H (VMCPD)    Virtual Math Coprocessor Device
0012H (EBIOS)    PS/2 Extended BIOS
0013H (BIOSXlat) BIOS protected mode translation
0014H (VNETBIOS) Virtual NetBIOS
0015H (DOSMGR)   Virtual MS-DOS Manager
0016H (WINLOAD)
0017H (SHELL)
0018H (VMPoll)
0019H (VPROD)
001aH (DOSNET)
001bH (VFD)      Virtual Floppy Device
001cH (LoadHi)   Global EMM Import
001dH (WINDEBUG)
001eH (TSRLoad)  TSR instance utility
001fH (BIOSHook) BIOS Interrupt hooker VxD

0020H (INT13)    Virtual INT 13H (BIOS Disk I/O) Device
0021H (PageFile) Demand Paging Swap Device services
0022H (SCSI)
0023H (MCA_POS)  Microchannel Architecture Programmable Option Select
0024H (SCSIFD)   SCSI FastDisk
0025H (VPEND)    Virtual Pen Device
0026H (APM)      Advanced Power Management

0200H (Novell IPX)
0202H (Win386 Soft-ICE/W Debugger)
0442H (VTDAPI)
0445H (VSBD)     Virtual SoundBlaster Device
1020H (VCV)      MS C/C++ 7. CodeView
28c0H (VXD.386)  Generic Virtual Device

IDs 0000H-1f00H are reserved for Microsoft VxDs (Virtual Devices). To
have Microsoft assign you a VxD ID of your very own, send Compuserve
email to INTERNET:[email protected].

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Some Published VxD IDs