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

DOSX is a specialized version of DPMI. Windows standard and extended mode kernel is a DPMI client app. Standard and extended mode kernel differs minimally and shares common codebase. Standard mode is just DPMI client, exnhanced mode is DPMI client running under Virtual Machime Manager. 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 provides Version 1.0 DPMI support, but reported as 0.9.

2021/08/05 12:15 · prokushev

Int 2FH, AH=16H, AL=8AH




Get Vendor-Specific API Entry Point


AX = 168AH
DS:(E)SI = selector:offset of ASCIIZ (null-terminated) string identifying the DPMI host vendor


if function successful
AL = 0
ES:(E)DI = extended API entry point
and DS, FS, GS, EAX, EBX, ECX, EDX, ESI, and EBP are preserved.
if function unsuccessful
AL = unchanged (8AH)


Returns an address which can be called to use host-specific extensions to the standard set of DPMI functions. This function is available only in protected mode.

The ASCIIZ string specifies a host 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 this function in preference to Int 31H Function 0A00H. This method of API extension is preferable to the Int 31H extension as it avoids the creation of a long (and consequently slow) chain of Int 31H handlers which would slow down time-critical DPMI functions. Note that although this function was not documented for DPMI 0.9, it will work under any DPMI 0.9 host.

See also


en/docs/dpmi/api/int2f/16/8a.txt · Last modified: 2021/09/02 16:59 by prokushev