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=00H, AL=02H
Version
0.9
Brief
Get Selector Increment Value
Input
AX = 0003H
Return
Carry flag = clear (this function always succeeds) AX = selector increment value
Notes
The DPMI functions Allocate LDT Descriptors (Int 31H Function 0000H) and Allocate DOS Memory Block (Int 31H Function 0100H) can allocate an array of contiguous descriptors, but only return a selector for the first descriptor. The value returned by this function can be used to calculate the selectors for subsequent descriptors in the array.
The increment value is always a power of two.
See also
Note
Text based on http://www.delorie.com/djgpp/doc/dpmi/