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[OM] Windoze & Memory [was question for Doctor Monitor, if he exists]

Subject: [OM] Windoze & Memory [was question for Doctor Monitor, if he exists]
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 14 Aug 2009 21:45:31 -0700
khen lim wrote:
> That's where I get most confused, Chuck. I read with great delight about 
> Windows' ability to access beyond the first 2GB via your Microsoft MSDN link 
> but I keep getting folks over here telling me no, Windows only reads 2GB and 
> nothing more. 

So I have this silly question. Who do you know in Malaysia who knows 
more about windoze than MS? If you can't even trust MS to know how their 
memory management options work, isn't it time to change OSs?

> The thing is you mentioned about modifying the boot.ini file so that Windows 
> can and will identify GB #3 and #4 and then assign them to applications. 

There are two separate control options.

"The */3GB* switch makes a full 3 GB of virtual address space available 
to applications and reduces the amount available to the system to 1 GB. 
... the amount of address space available to applications can be 
adjusted by setting the */USERVA* switch in Boot.ini to a value between 
2048 and 3072, which increases the amount of address space available to 
the system."

And indeed, Windows Task Manager on this machine recognizes 3GB of memory.
> That would be good but what does one write to modify this file? 

I have no boot.ini in Vista. The entires are in the Registry. I just 
don't remember what I used, although I'm sure I didn't modify the 
Registry directly. I seem to recall some program/utility. I know I found 
everything I needed on the web.
------------------
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002
SystemStartOptions
/3GB /USERVA=3072
------------------

This is all for real, I've done it and had it working since shortly 
after buying this machine. It did indeed speed up PS.

> Secondly with computers these days using unified or shared memory 
> architecture (with graphics adaptor), would GB #3 and #4 be assigned instead 
> to such devices to use so that the first 2GB can be left to the operating 
> system. 

You are on the right track, but the wrong memory amount. Windoze can 
address 4GB. However, as you say, many hardware devices use part of that 
4GB address space to map their own memory. The graphics card is usually 
the largest, which is one reason not to use a huge memory gamers card 
for an image editing system. Add a SCSI card, lose some memory. MS says 
a common amount of memory address space used by various hardware is 
7-800MB, leaving 3.2-3.3GB for Windoze to use.

That's why my system only has 3GB of physical memory on the motherboard. 
It was considerably cheaper at the time than 4GB, and the practical 
difference is small. Most of the top GB would be mapped out by various 
hardware drivers, and never used.

> I'm confused as you can see.
>   

Perhaps a little less so by now?

Moose
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