Table of Contents

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.

2021/08/05 10:15 · prokushev · 0 Comments

Int 31H, AH=05H, AL=02H

Version

0.9

Brief

Free Memory Block

Input

AX = 0502H
SI:DI = memory block handle

Return

if function successful
Carry flag = clear

if function unsuccessful
Carry flag = set
AX = error code
8023H	invalid handle

Notes

This call will correctly free all of the possible page types that can occur in a memory block: committed pages, uncommitted pages, and mapped pages (see Appendix A: Glossary).

No descriptors are freed by this call. It is the client's responsibility to free any descriptors that it previously allocated to map the memory block. Descriptors should be freed before linear memory blocks.

See also

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
2021/08/13 14:23 · prokushev · 0 Comments