DOS ain't dead

INT 15.87 in protected mode (Developers)

posted by Rugxulo , Usono, 01.09.2011, 04:31

> No, that's not possible. As Japheth pointed out, a DPMI host running as
> VCPI client needs to switch to V86, it mustn't switch to RM instead. (A
> DPMI host running stand-alone (from RM and without VCPI) could switch
> either to RM or to V86, but in the latter case it would need to set up and
> manage the V86 environment itself.)

Right, which I meant CWSDPMI does not do (for whatever reason). I don't know how others fare, e.g. HDPMI32.

(old post on comp.os.msdos.djgpp, 05 Jun 1997):

>>> (Eric Lange): I noticed in the DPMI 0.9 spec that this is
>>> only an OPTION for DPMI servers, but they can also run in real mode.
>
>> (Charles Sandmann): CWSDPMI actually does BOTH. If you are running
>> under HIMEM (or bare) CWSDPMI will leave the machine in real mode when
>> running DOS (since I didn't want to bother writing a V86 monitor). If
>> you are running under an EMM, CWSDPMI uses the V86 provided.

Also, Prashant's pmode overview site says this (feel free to disagree):

> ... the time taken by the CPU to switch from protected mode to real
> mode is considerable and greatly slows down the program. By running the
> program in V86 mode, the program is actually executed faster.

Complete thread:

• INT 15.87 in protected mode - Laaca, 29.08.2011, 14:11
  • INT 15.87 in protected mode - Rugxulo, 29.08.2011, 23:28
    • INT 15.87 in protected mode - Japheth, 30.08.2011, 05:27
      • INT 15.87 in protected mode - Rugxulo, 30.08.2011, 05:37
      • INT 15.87 in protected mode - Laaca, 30.08.2011, 07:22
        • INT 15.87 in protected mode - Japheth, 30.08.2011, 08:47
          • INT 15.87 in protected mode - Rugxulo, 31.08.2011, 01:30
            • INT 15.87 in protected mode - Laaca, 31.08.2011, 07:33
              • INT 15.87 in protected mode - Rugxulo, 31.08.2011, 21:27
                • INT 15.87 in protected mode - Laaca, 02.09.2011, 07:10
                  • INT 15.87 in protected mode - marcov, 02.09.2011, 09:58
                    • INT 15.87 in protected mode - Rugxulo, 03.09.2011, 21:49
                      • INT 15.87 in protected mode - DOS386, 04.09.2011, 12:43
            • INT 15.87 in protected mode - Japheth, 31.08.2011, 10:11
              • INT 15.87 in protected mode - Rugxulo, 31.08.2011, 21:25
                • INT 15.87 in protected mode - ecm, 01.09.2011, 02:17
                  • INT 15.87 in protected mode - Rugxulo, 01.09.2011, 04:31
                    • INT 15.87 in protected mode - Rugxulo, 01.09.2011, 05:00
  • INT 15.87 in protected mode - RayeR, 07.09.2011, 10:28
    • INT 15.87 in protected mode - Laaca, 07.09.2011, 12:28
      • INT 15.87 in protected mode - RayeR, 07.09.2011, 21:05
        • INT 15.87 in protected mode - Laaca, 08.09.2011, 07:33
          • INT 15.87 in protected mode - bretjohn, 08.09.2011, 18:19
            • INT 15.87 in protected mode - Laaca, 08.09.2011, 22:39
              • INT 15.87 in protected mode - Rugxulo, 08.09.2011, 22:50
          • INT 15.87 in protected mode - RayeR, 08.09.2011, 22:27
            • INT 15.87 in protected mode - bretjohn, 09.09.2011, 00:31
              • INT 15.87 in protected mode - RayeR, 09.09.2011, 01:51
                • INT 15.87 in protected mode - bretjohn, 09.09.2011, 20:09
                • INT 15.87 in protected mode - bretjohn, 09.09.2011, 23:17