[Freedos-user] DPMI with 4 GB

[Roberto Waldteufel]

Hi All,   No I am not using Himem.Sys or Himem.exe. I am writing for 32-bit protected mode, so I need DPMI for the flat memory model, which in theory should enable the use of all 4 GB of RAM on my system, not just extra high memory in the real mode. No such real mode high memory manager is needed under CWSDPMI.   I don't think the motherboard is the cause of the trouble - I had this computer custom built by Dell with 4 x 1 GB chips. It came with Windows XP (Home) preinstalled, which demands over 2 GB just for Windows, leaving my applications only about 1.75 GB to use, which is my main reason for wanting to write for the DOS platform so as to have all of the 4 GB available, but the CWSDPMI server only seems to recognise 2 GB, which is at least a small improvement over Windows as I gain about about 250 MB extra RAM. However, Windows is so bloated it actually uses the other 2.25 GB of RAM, whereas Freedos is nice and lean and doesn't need such an excessive amount of memory for its own use - it's just that the DPMI server doesn't see more than 2 GB of physical RAM. However, the fact that Windows can access the remaining RAM for its own use proves that the motherboard must be able to cope with the full 4 GB of physical RAM.   Yes I did try DPMIONE (for which high end real mode memory IS needed - I used the himem.sys file to load himem.exe and emm386 for this) instead of CWSDPMI but I found this even worse, with only 64 MB of RAM visible to my applications under this DPMI server! I have not tried DOS32A yet, but will look into this.   Best Wishes,   Roberto