DOS Protected Mode Interface

DOS Protected Mode Interface, short DPMI, is an API for developing DOS-based applications that are more than the so-called " conventional memory " of 640 KB ( 655,360 bytes, see also UMB ) use directly without detours via bank switching, XMS, EMS and the like.

Details

The DPMI API exists as 16 - and 32 -bit API and hides all the technical details of the protected-mode programming of the newer Intel processors (from the Intel 80286 ) prior to the application program. Usually the DPMI API is provided by a supplied external auxiliary program called DOS - Extender. Thus, use (such as a DOS program ) functions of the protected mode real mode program, by calling the corresponding DPMI functions. The DOS extender then switches to protected mode, performs the desired function, switch back to real mode, and returns control to the application program.

On Windows, DPMI is provided directly by the operating system. The DOS extender detect this case and then reduced to the pass through of appropriate calls.

DOS extender implementations

Well-known DOS - Extender:

  • In Borland compilers (among Borland Pascal 7.0 ) used RTM.EXE (16 - bit) and RTM32.EXE (32- bit only in Turbo C )
  • DOS4GW.EXE (supplied with Watcom C / C , very popular until 1995, then set development, now obsolete )
  • PMODE / W
  • Causeway
  • DOS/32A ( to DOS4GW.EXE compatible, last version 9.12 of 2006)
  • CWSDPMI (part of DJGPP, there referred to as go32. )
  • PMODE / DJ
  • WDOSX
  • HDPMI16 (16 - bit) and HDPMI32 (32 -bit ) from the HX DOS Extender
  • TNT DOS - Extender SDK Phar Lap
  • 386 | DOS - Extender SDK Phar Lap
  • Emx by Eberhard Mattes
  • Programming
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