On Wed, Jan 8, 2014 at 8:48 AM, Bernd Blaauw <bbla...@home.nl> wrote:
> dmccunney schreef op 8-1-2014 12:43:
>
>> I did not miss his point.  I suggested a technique he could use to
>> soak up *some* of his system memory.  I'm quite aware DOS and DOS apps
>> can't use *all* of it, and that 4GB is the most he can use..
>
> DOS drivers work within a single 4GB memory section, and lots of stuff
> gets taken out of it by memory-mapped hardware. For example my current
> machine only seems to find 1506MB in DOS and ReactOS. Perhaps system
> memory for integrated graphics takes away quite a bit of the 1st 4GB area.

Likely.  And Intel x86 uses a segmented architecture, and 4GB is the
size of a segment on a 32 bit x86 chip.  Accessing memory beyond that
requires more complex programming.  I certainly can't see anyone
expending the effort for a 16 bit OS.

I think you're correct about the integrated graphics grabbing a chunk
of the first segment.

>> I have a 2GB partition allocated to FreeDOS on the machine where it
>> lives, and I'm not coming close to using all of it.  I could put the
>> entire FreeDOS drive on a ramdisk if the machine had that much ram to
>> spare.
>
> I don't know what to fill up DOS systems with either, not using them
> exclusively enough I'm afraid.

The machine FreeDOS is on here is an ancient Fujitsu Lifebook p2110
notebook, with an 867mhz Transmeta Crusoe CPU, 256MB RAM (and the CPU
grabs 16MB off the top for code morphing), and a 40GB IDE4 HD.
FreeDOS is on a 2GB FAT32 filesystem.

I allocate a ramdisk and copy various things to it on startup, then
adjust the PATH to make the ramdisk first, plus setting TEMP and TMP
to point to it, and allocate a disk cache.  FreeDOS flies.  The
machines multiboots Win2K Pro, Ubuntu, and Puppy Linux as well.  They
walk slowly or crawl, depending upon exactly what I'm doing.

If I had enough RAM, I could run FreeDOS entirely from a ramdisk, but
the Lifebook *can't* be expanded that much.

Ubuntu tries to run ram resident if enough is available.  I had a
weird problem on my desktop with an older mobo, which would
occasionally forget a drive existed.  I was in Ubuntu, trying to do
updates, and they were failing because the filesystem to update wasn't
there.  The drive where Ubuntu was had dropped out.  Because Ubuntu
was essentially running in RAM, I could shut down and fiddle.  I can
only imagine what Windows reaction would have been.  :-}

> Bernd
______
Dennis

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