If the hardware is capable of addressing more than 4GB via bank
switching or direct 64 bit addressing, some suitable software should be
able to use the upper memory without interfering with Windows claims on
the lower 4GB... assuming that Windows agrees to let it.
Chuck Norcutt
Mike Lazzari wrote:
>> Yes, XP only addressable to 2GB, as I memtioned below I have assigned 2.5GB
>>> as RAMDISK with Vsuite Ramdisk, the software can access to the hidden
>>> memory.
> I've thought about setting up a RAMdisk as I had on my old 8086 but
> don't see much benefit. In that box I had a big RAMdisk card full of
> memory which originally cost over $2k. Maybe I'm wrong about the current
> systems and should try a RAMdisk.
>
> First of all I thought that windows32bit could address something like
> 3.2gb? At least that's what my computer reports depending on switches
> set in boot.ini. I believe it reserves some of that memory for its own
> use, e.g. addressing the video. Maybe that's where you get the +/-2gb
> _usable_ memory. In any event the memory between the usable amount and
> the addressable 3.2gb would not be available for a RAMdisk. Or at least
> it would be counter productive as it reduces the usable amount addressed
> directly by windows for apps. Perhaps it would be beneficial if you had
> more that 4gb installed on a 32bit system.
>
> Secondly, How does windows address the RAMdisk? I assumed that it would
> have to page it in/out in blocks using available memory? If so this
> would increase the memory windows reserves and further reducing direct
> access memory used for apps. Also this paging would be a bottleneck
> slowing the RAMdisk memory. True, still much faster than a swap to hard
> disk but wouldn't it be faster to just let windows use the memory and
> paging block for apps? It seems to me that with 4gb of RAM on a 32bit
> system a RAMdisk would have to be smaller than 1gb and that seems hardly
> worthwhile. But my presumptions may easily be way out of date.
>
> Mike
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