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. Windows in Standard Mode provides DPMI services only for Windows Applications, not DOS sessions.

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

Int 31H, AH=02H, AL=01H

Version

0.9

Brief

Set Real Mode Interrupt Vector

Input

AX = 0201H
BL = interrupt number
CX:DX = segment:offset of real mode interrupt handler

Return

Carry flag = clear (this function always succeeds)

Notes

The address passed in CX must be a real mode segment address, not a selector. Consequently, the interrupt handler must either reside in DOS memory (i.e. below the 1 MB boundary) or the client must allocate a real mode callback address. See Int 31H Functions 0100H and 0303H.

If the interrupt being hooked is a hardware interrupt, the memory that the interrupt handler uses must be locked.

See also

AH=25

Note

Text based on http://www.delorie.com/djgpp/doc/dpmi/

DPMI
Process manager	INT 2FH 1680H, 1687H
Signals
Memory manager
Misc	INT 2FH 1686H, 168AH
Devices