Note: This API calls are shared between DOS and Win16 personality.

DPMI is a shared interface for DOS applications to access Intel 80286+ CPUs services. DOS DMPI host provides core services for protected mode applications. Multitasking OS with DOS support also provides DMPI in most cases. Windows standard and extended mode kernel is a DPMI client app. Standard and extended mode kernel differs minimally and shares common codebase. Standard Windows kernel works under DOSX extender. DOSX is a specialized version of 16-bit DPMI Extender (but it is standard DPMI host). Standard mode is just DPMI client, exnhanced mode is DPMI client running under Virtual Machime Manager (really, multitasker which allow to run many DOS sessions). Both modes shares DPMI interface for kernel communication. The OS/2 virtual DOS Protected Mode Interface (VDPMI) device driver provides Version 0.9 DPMI support for virtual DOS machines. Win16 (up to Windows ME) provides Version 0.9 DPMI support.

DPMI host often merged with DPMI extender. Usually DPMI extender provide DPMI host standard services and DOS translation or True DPMI services.

2021/08/05 12:15 · prokushev

Int 31H, AH=0AH, AL=00H




Get Vendor-Specific API Entry Point


AX = 0A00H
DS:(E)SI = selector:offset of ASCIIZ (null-terminated) string which identifies the DPMI host vendor


if function successful
Carry flag = clear
ES:(E)DI = selector:offset of extended API entry point
and DS, FS, GS, EAX, EBX, ECX, EDX, ESI, and EBP may be modified.

if function unsuccessful
Carry flag = set
AX = error code
8001H	unsupported function (extension not found)


Returns an address which can be called to use host-specific extensions to the standard set of DPMI functions. DPMI 1.0 clients should avoid use of this function.

The null-terminated string specifies the host-specific vendor name or some other unique identifier to obtain a specific extension entry point. The string comparison used to look up the API entry point is case-sensitive.

Clients must use a FAR CALL to reach the extended API entry point.

All extended API parameters are specified by the vendor.

DPMI 1.0 clients should use Int 2FH Function 168AH in preference to this function. DPMI 1.0 hosts support this function solely for backward compatibility with DPMI 0.9 clients.

See also


Process manager INT 2FH 1680H, 1687H
Memory manager
Misc INT 2FH 1686H, 168AH
2021/08/13 16:23 · prokushev

en/docs/dpmi/api/int31/0a/00.txt · Last modified: 2021/08/27 08:22 by prokushev