utilizing 4gb memory on 32bit OS

[cRABu]

edit c:\boot.ini

after you will open it with notepad, or some sort it will look somehow like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Home Edition" /PAE /FASTDETECT

 

[cRABu]

If your CPU supports DEP you can olso use /NOEXECUTE=OPTIN instead of /PAE, but this swich is by default enabled by windows, if your cpu supports DEP. I am using Centrino duo core and it supports DEP( in my boot.ini file the nonexecute swich is present by default) BTW what cpu do you have?.

/NOEXECUTE
This option is only available on 32-bit versions of Windows when running on processors supporting no-execute protection. It enables no-execute protection (also known as Data Execution Protection - DEP), which results in the Memory Manager marking pages containing data as no-execute so that they cannot be executed as code. This can be useful for preventing malicious code from exploiting buffer overflow bugs with unexpected program input in order to execute arbitrary code. No-execute protection is always enabled on 64-bit versions of Windows on processors that support no-execute protection. There are several options you can specify with this switch:
/NOEXECUTE=OPTIN Enables DEP for core system images and those specified in the DEP configuration dialog.

 

[tyttebøvs]

im still a little bit confused. i still dont get 'address space' and how it needs to be appointed. with 4 sticks of 1gb each, will the 3.25gb that the computer sees get evenly distributed between all 4 sticks? or is pretty much one stick just dead weight and how do i know which one?

http://dlsvr01.asus.com/pub/ASUS/mb/4GB_Rev1.pdf gives some insight into what is going on in the address space. When running dual channel, the missing ram is shared between the modules.

PAE gives support for DEP in XP/SP2 and in Vista, nothing more. So you cannot use that to go beyond 4G

 

[cRABu]

tyttebøvs
yes you can, you can go up to 64gb.

The x86 processor hardware is augmented with additional address lines used to select the additional memory, so physical address size is increased from 32 bits to 36 bits. This increases maximum physical memory size from 4 GiB to 64 GiB. The 32-bit size of virtual address is not changed, so regular application software continues to use instructions with 32-bit addresses and (in a flat memory model) is limited to 4 gibibytes (GiB). The operating system uses page tables to map this 4 GiB address space onto the 64 GiB of total memory, and the map is usually different for each process. In this way the extra memory is useful even though no single regular application can access it all simultaneously.



there is a lot to read on pae, if you want to learn about it.

 

[tyttebøvs]

You can actually go even higher, depending on the implementation of PAE, but even if the CPU allows for more than 32 to be used, the memory manager in xp and vista doesn't use them. You can go so far as to say Microsoft has crippled the PAE kernel

 

[voyagerfan99]

My XP won't even detect 3 GB. I just bought 2 GB and had 1 gig of 512's and it only detects 2.75

 

[cRABu]

it depends on the memory mapping also. you can use the /PAE as well.

 

[tyttebøvs]

The remapper tends to remap on a boundary, so most often you actually loose more ram by having the remapper enabled on 32bit xp and vista, because still, any ram above 4G is useless

 

[WhiteFireDragon]

if i just settle with windows seeing 3gb with 4x1gb sticks in there, then will each stick run cooler since the heat can spread on all or will only 3 of the sticks heat up?

 

[cRABu]

it doesen't matter how many sticks you use, as long as you are not running at dual channel.

 

[WhiteFireDragon]

well i only have 4 slots so they have to be in dual channel since all 4 sticks will be used. wouldn't i benefit from dual channel mode anyways instead of 4 different sticks?

 

[voyagerfan99]

it doesen't matter how many sticks you use, as long as you are not running at dual channel.

So if I don't run them in Dual-Channel then it'll read all 3 GB's of memory?

And I actually have to use memory remapping in order to even see 2.75 GB of memory, otherwise I only see 2.5 GB with memory remapping off.

 

[cRABu]

i was refering to somethin else about the dual channel stuff. The 32bit architecture is causing your system to only use 2,75 GB instead of 3. The 32bit achitecture is capable of accessing 4gb of ram( IN THEORY) - the amount used for addressing your video card and other stuff.(so in real word only 2,5-3.5gb). There is nothing you can do, only to use the /PAE switch in boot.ini, or to install a 64bit OS. I see you are using Athlon 64, and in this case i recommend using win 64bit. Your applications running at 32 bit will not be influenced by the x64 OS.

 

[Cromewell]

only to use the /PAE switch in boot.ini

Which will not extend the address range beyond 4GB in windows XP for driver compatability.

 

[voyagerfan99]

i was refering to somethin else about the dual channel stuff. The 32bit architecture is causing your system to only use 2,75 GB instead of 3. The 32bit achitecture is capable of accessing 4gb of ram( IN THEORY) - the amount used for addressing your video card and other stuff.(so in real word only 2,5-3.5gb). There is nothing you can do, only to use the /PAE switch in boot.ini, or to install a 64bit OS. I see you are using Athlon 64, and in this case i recommend using win 64bit. Your applications running at 32 bit will not be influenced by the x64 OS.

I have been thinking of getting a copy of XP Pro 64-bit. I just don't have the money for it right now.

NewEgg should still be selling XP after June, right?

 

[cRABu]

i guess so. There is also a copy of Vista that runs on 64 bit.

 

[Crimsonite]

The missing GB or MB of your installed physical memory is being used by Windows to map other hardware such as video RAM and/or even soundcard RAM (ie. XRAM on X-Fi).

 

[WhiteFireDragon]

The missing GB or MB of your installed physical memory is being used by Windows to map other hardware such as video RAM and/or even soundcard RAM (ie. XRAM on X-Fi).

what do you mean by map? so basically is it being put to good use (making comp faster) is mapping memory a waste? i still don't fully understand terms like address or map

 

[Cromewell]

what do you mean by map? so basically is it being put to good use (making comp faster) is mapping memory a waste? i still don't fully understand terms like address or map

I'll try explaining this a different way (it will still say the same thing though).

A 32bit CPU can address 4GB of memory. To be able to use other devices (stuff integrated on the motherboard, add-in cards, video card, etc) some address have to be given to them.

Say your address range looks like this:
<-------------------------------------- Memory ------------------------------------>

Addresses are then taken from the high end of the range and given to devices. So then your address range looks like this:
<---------------------- Memory ---------------------| |----Devices----------------->

Any memory though would be given an address beyond the new limit, cannot be addressed.

Does that make more sense?

 

[royalmarine]

I'll try explaining this a different way (it will still say the same thing though).

A 32bit CPU can address 4GB of memory. To be able to use other devices (stuff integrated on the motherboard, add-in cards, video card, etc) some address have to be given to them.

Say your address range looks like this:
<-------------------------------------- Memory ------------------------------------>

Addresses are then taken from the high end of the range and given to devices. So then your address range looks like this:
<---------------------- Memory ---------------------| |----Devices----------------->

Any memory though would be given an address beyond the new limit, cannot be addressed.

Does that make more sense?

cromewell when you say 32bit cpu do you mean 32bit OS or are you on about an actual 32bit processor?

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