DOS ain't dead

DOS and 4 GB of memory (Users)

posted by Rugxulo , Usono, 31.07.2008, 20:00

> I'm surprised the HIMEM.SYS even sees above 2 GB, and I was able to use HX
> DOS-extender to run Win32 apps like PIFAST 4.3, and utilize above & beyond
> 3 GB of memory.
>
> What is the closes anyone on this board has gotten to utilizing the full 4
> GB on their DOS systems?

Not nearly that much because I only have 1 GB RAM on this laptop.
Yesterday I did use about 850 MB in testing paq8o8z (although it didn't barely help more than 133 MB did).

> Can 16-bit apps be tweaked to see > 2 GB. Specifically, I'm wanting to
> create a RAMDISK over 2 GB in FAT16, utilizing 64-kb clustersize.

XMSv3 supports really large amounts of RAM, so you can use SHSURDRV (386 version) to make a really big RAM disk. It comes w/ NASM src.

XMSv2 is the 16-bit variant, and I think that usually maxes out at 64 MB (even though a 286 can only max. handle 16 MB). So not sure what you mean by "16-bit apps", but in general, you probably want 386+.

> What about PAE -extensions in DOS to utilize > 4 GB memory on a 64-bit
> CPU?

Untested by me, but there is a DOS/32A PAE hack (usable by OpenWatcom/DOS/32-bit, e.g. LE/LX format only):


[2007-01-14]: dos32a_PAE_update.zip - by Charles Hyde - updated PAE patch

> All thoughts & comments on this much appreciated!

CWSDPMI r5 limits you to 512 MB. As you've noticed, HDPMI32 doesn't have such limitations. I think CWSDPMI r6 (beta) is better for large RAM. It can use 4 MB pages, which is faster, and it won't swap out on you as soon either (once 512k page tables are used low). And as far as DJGPP's libc goes, I think it has 2 GB signed pointer issues, so you may have to use sbrk() directly instead of indirectly via malloc(). In other words, CWS has suggested call sbrk() twice in succession for 1.5 GB each time if you want to alloc 3 GB. (PMODE/DJ can alloc 2 GB okay too, supposedly, but it's considered not as good.)

Complete thread:

• DOS and 4 GB of memory - Zyzzle, 31.07.2008, 00:35 (Users)
  • DOS and 4 GB of memory - marcov, 31.07.2008, 10:56
    • DOS and 4 GB of memory - ecm, 31.07.2008, 16:32
    • DOS and 4 GB of memory - RayeR, 31.07.2008, 23:23
      • DOS and 4 GB of memory - marcov, 01.08.2008, 12:39
        • DOS and 4 GB of memory - Zyzzle, 01.08.2008, 23:37
          • DOS and 4 GB of memory - Rugxulo, 02.08.2008, 08:12
            • DOS and 4 GB of memory - RayeR, 03.08.2008, 00:59
              • DOS and 4 GB of memory - Japheth, 03.08.2008, 06:15
                • DOS and 4 GB of memory - Rugxulo, 06.08.2008, 01:11
                  • DOS and 4 GB of memory - Japheth, 06.08.2008, 07:15
                    • DOS and 4 GB of memory - Rugxulo, 07.08.2008, 05:37
                      • DOS and 4 GB of memory - Japheth, 07.08.2008, 10:08
                  • DOS and 4 GB of memory - RayeR, 06.08.2008, 15:09
  • DOS and 4 GB of memory - Steve, 31.07.2008, 13:00
  • DOS and 4 GB of memory - Rugxulo, 31.07.2008, 20:00
    • DOS and 4 GB of memory (CWSDPMI) - Rugxulo, 01.08.2008, 05:01
      • DOS and 4 GB of memory (CWSDPMI) - RayeR, 11.08.2008, 17:28
        • DOS and 4 GB of memory (CWSDPMI) - Rugxulo, 12.08.2008, 07:20
          • DOS and 4 GB of memory (CWSDPMI) - RayeR, 12.08.2008, 11:43
            • DOS and 4 GB of memory (CWSDPMI) - Rugxulo, 14.08.2008, 04:28
    • DOS and 4 GB of memory - Zyzzle, 04.08.2008, 00:13
      • DOS and 4 GB of memory - rr, 04.08.2008, 09:26
        • DOS and 4 GB of memory - Rugxulo, 04.08.2008, 23:19