XP 32 bit Memory

[John Callaway]

How much memory can XP 32 bit OS handle? I want to have Dell build a
dual boot Laptop with both Windows 7 OS & XP 32 bit OS on it. I would
like to have 8 Gig of ram if it XP 32 will handle it.

JPC

 

[John John - MVP]

Windows XP 32-bit supports a maximum of 4GB of RAM but due to address
space requirement for hardware addressing you will not be able to use
the full 4GB, depending on the hardware installed in the machine the
available RAM could be anywheres between 2.75 to 3.5GB.

John

 

[Ken Blake, MVP]

How much memory can XP 32 bit OS handle? I want to have Dell build a
dual boot Laptop with both Windows 7 OS & XP 32 bit OS on it. I would
like to have 8 Gig of ram if it XP 32 will handle it.

It will not handle it. Neither will Windows 7 (unless it's 64-bit
Windows 7). Moreover, it's very likely considerably more than you can
make effective use of in either operating system.

Here's the scoop:

All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.

But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

 

[Roy Smith]

How much memory can XP 32 bit OS handle? I want to have Dell build a
dual boot Laptop with both Windows 7 OS & XP 32 bit OS on it. I would
like to have 8 Gig of ram if it XP 32 will handle it.

The most a 32 bit version of Windows can have is 4 GB. That said it is
unlikely that you'll ever see more that 3.2 GB of free memory. This is
because all of your devices attached to your PC take up memory address
spaces for things they need to work (i.e. drivers, etc).

 

[John Callaway]

The most a 32 bit version of Windows can have is 4 GB. That said it is
unlikely that you'll ever see more that 3.2 GB of free memory. This is
because all of your devices attached to your PC take up memory address
spaces for things they need to work (i.e. drivers, etc).

OK. I get it. I'll only get 3 gig for ram.
Now what do you think of the idea of a dual boot for XP 32 and windows
7 on the same laptop? Having XP 32 the default OS and using windows 7
when I choose, using a 64 bit processor around 3 gHrtz? I'm wondering
about driver compatibility etc and using XP 32 bit OS with a 64 bit
processor.

JPC

 

[Roy Smith]

In message <#[email protected]>, Roy Smith

Is this why many netbooks have a maximum of 2G?

No that's a hardware limitation and has nothing to do with Windows RAM
size limit.

 

[Klaus Jorgensen]

John Callaway formulated the question :

OK. I get it. I'll only get 3 gig for ram.

Use the remaining 5Gb as a RAM drive for temporary files etc.
http://www.trap17.com/index.php/4gb-Xp-32bits_t67548.html

 

[Victor Haberkorn]

How much memory can XP 32 bit OS handle? I want to have Dell build a
dual boot Laptop with both Windows 7 OS & XP 32 bit OS on it. I would
like to have 8 Gig of ram if it XP 32 will handle it.

JPC

32 bits' OS only suport 3,25 Gig. More than that you have to install a 64 bits.

 

[Ken Blake, MVP]

32 bits' OS only suport 3,25 Gig.

Sorry, that's not correct. The number is variable. Here's the way it
works:

All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.

But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

 

[John Callaway]

In message <[email protected]>, "Ken Blake,

All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.

But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

[]
Since the hardware presumably doesn't need much, presumably the RAM
_beyond_ the hardware address _could_ be used, if someone were to write
a suitable "memory manager" (as used to be done in the early days of DOS
to get round the "640k" limit (and even a little around 1M, IIRR).
Unless the hardware uses incomplete address decoding, that is.

If such a manager were to be written, of course, only software that knew
about it could use it (like DOS software that either knew about being
"loaded high" or didn't), so there probably would be insufficient
usefulness for it to be worth anybody's while, since software houses
would be unlikely to cater for it.

That won't happen on NT operating systems, the kernel will simply not
allow it.

John

Ken Blake,
I do appreciate all the info on this matter. I recently
purchased a Dell laptop with W7 OS. I could not install some older
programs on it, so I tried to install XP 32 bit OS on a partition
that I resized with W7. The CD/DVD drive would not fully load the
install disc. I returned the computer. I have since done some research
and found out that if I have XP 32 Bit OS on the computer and then
load W 7 on it, it seems to go better. So I intend to buy another Dell
with W 7 OS, then resize the partition, making room for XP 32 bit OS
on the other partition. I will then Ghost the W 7 partition using
Norton. I will then load XP 32 bit OS over the W 7 OS providing the
CD/DVD will read the XP install disc. Then Ghost the W 7 OS on the
other partition. I have downloaded EasyBC boot loader utility to have
the option to dual boot to which OS I want on boot up.
Ken, am I on the right track?

John P. Callaway

 

[Ken Blake, MVP]

Ken Blake,
I do appreciate all the info on this matter. I recently
purchased a Dell laptop with W7 OS. I could not install some older
programs on it, so I tried to install XP 32 bit OS on a partition
that I resized with W7. The CD/DVD drive would not fully load the
install disc. I returned the computer. I have since done some research
and found out that if I have XP 32 Bit OS on the computer and then
load W 7 on it, it seems to go better. So I intend to buy another Dell
with W 7 OS, then resize the partition, making room for XP 32 bit OS
on the other partition. I will then Ghost the W 7 partition using
Norton. I will then load XP 32 bit OS over the W 7 OS providing the
CD/DVD will read the XP install disc. Then Ghost the W 7 OS on the
other partition. I have downloaded EasyBC boot loader utility to have
the option to dual boot to which OS I want on boot up.
Ken, am I on the right track?

Sorry, although I'd like to help if I could, I've never had any
interest in dual-booting and know next to nothing about it.

Perhaps someone else here can answer your question.

 

[Tim Meddick]

Absolutely no need for "3rd-party boot loaders" as Win7 will easily cope with
multi-booting Windows NT-based OSs (although, personally, I have had some problems
getting the NT bootloader to boot MS-DOS-based Windows...).

==

Cheers, Tim Meddick, Peckham, London.

In message <[email protected]>, "Ken Blake,
[]
All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.

But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.
[]
Since the hardware presumably doesn't need much, presumably the RAM
_beyond_ the hardware address _could_ be used, if someone were to write
a suitable "memory manager" (as used to be done in the early days of DOS
to get round the "640k" limit (and even a little around 1M, IIRR).
Unless the hardware uses incomplete address decoding, that is.

If such a manager were to be written, of course, only software that knew
about it could use it (like DOS software that either knew about being
"loaded high" or didn't), so there probably would be insufficient
usefulness for it to be worth anybody's while, since software houses
would be unlikely to cater for it.

That won't happen on NT operating systems, the kernel will simply not
allow it.

John

Ken Blake,
I do appreciate all the info on this matter. I recently
purchased a Dell laptop with W7 OS. I could not install some older
programs on it, so I tried to install XP 32 bit OS on a partition
that I resized with W7. The CD/DVD drive would not fully load the
install disc. I returned the computer. I have since done some research
and found out that if I have XP 32 Bit OS on the computer and then
load W 7 on it, it seems to go better. So I intend to buy another Dell
with W 7 OS, then resize the partition, making room for XP 32 bit OS
on the other partition. I will then Ghost the W 7 partition using
Norton. I will then load XP 32 bit OS over the W 7 OS providing the
CD/DVD will read the XP install disc. Then Ghost the W 7 OS on the
other partition. I have downloaded EasyBC boot loader utility to have
the option to dual boot to which OS I want on boot up.
Ken, am I on the right track?

John P. Callaway

 

[John John - MVP]

In message <[email protected]>, "Ken Blake,

All 32-bit client versions of Windows (not just Vista/XP/7) have a 4GB
address space (64-bit versions can use much more). That's the
theoretical upper limit beyond which you can not go.

But you can't use the entire 4GB of address space. Even though you
have a 4GB address space, you can only use *around* 3.1GB of RAM.
That's because some of that space is used by hardware and is not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but can
range from as little as 2GB to as much as 3.5GB. It's usually around
3.1GB.

Note that the hardware is using the address *space*, not the actual
RAM itself. If you have a greater amount of RAM, the rest of the RAM
goes unused because there is no address space to map it to.

[]
Since the hardware presumably doesn't need much, presumably the RAM
_beyond_ the hardware address _could_ be used, if someone were to write
a suitable "memory manager" (as used to be done in the early days of DOS
to get round the "640k" limit (and even a little around 1M, IIRR).
Unless the hardware uses incomplete address decoding, that is.

If such a manager were to be written, of course, only software that knew
about it could use it (like DOS software that either knew about being
"loaded high" or didn't), so there probably would be insufficient
usefulness for it to be worth anybody's while, since software houses
would be unlikely to cater for it.

That won't happen on NT operating systems, the kernel will simply not
allow it.

John

 

[dennis]

That won't happen on NT operating systems, the kernel will simply not
allow it.

There is built-in support in the kernel for an application to map
unmanaged memory.

 

[John John - MVP]

There is built-in support in the kernel for an application to map
unmanaged memory.

AWE, only for the applications own use, you can't develop a memory
manager around this, the kernel will not allow this to manage other
processes' memory. On 32-bit systems AWE will only be able to access
RAM above the 4GB barrier if the operating system is PAE capable, 32-bit
XP can't do it. Few applications are AWE capable, this is mostly
reserved for large database programs and other such applications.

John

 

[dennis]

AWE, only for the applications own use, you can't develop a memory
manager around this, the kernel will not allow this to manage other
processes' memory. On 32-bit systems AWE will only be able to access
RAM above the 4GB barrier if the operating system is PAE capable, 32-bit
XP can't do it. Few applications are AWE capable, this is mostly
reserved for large database programs and other such applications.

I'm not talking about AWE, but about mapping "device" space (physical
memory). That way you can use memory above 4G also in 32bit XP.

XP supports PAE. Its own memory manager just doesn't allow access to
memory above 4G.

 

[John John - MVP]

I'm not talking about AWE, but about mapping "device" space (physical
memory). That way you can use memory above 4G also in 32bit XP.

XP supports PAE. Its own memory manager just doesn't allow access to
memory above 4G.

XP supports PAE for DEP only, drivers and applications can't access the
memory above the 4GB barrier. From what I understand memory above the
4GB barrier was available with PAE when XP was released but too many
drivers were misbehaving and causing BSODs so Microsoft decided to put
an end to this in SP1.

I know that a certain RAM disk can apparently make use of the memory
above the 4GB barrier, I guess this is what you mean by "device space".
Although the RAM drive can map the space for use as temporary storage
for other applications the other applications still cannot use this for
their process space, the memory manager does not permit any applications
to directly manage other processes' space. Other than snake oil memory
memory optimizers there are no third party memory managers for NT
operating systems.

John

 

[dennis]

John John - MVP wrote:

I know that a certain RAM disk can apparently make use of the memory
above the 4GB barrier, I guess this is what you mean by "device space".

With device space I mean this:
http://msdn.microsoft.com/en-us/library/ms801998.aspx

And yes, some ram-disks uses that to use memory above 4G.

Although the RAM drive can map the space for use as temporary storage
for other applications the other applications still cannot use this for
their process space

True, you need a bit more to use that kind of memory for other than data
storage.

 

[dennis]

When I suggested a memory manager, I wasn't talking about going beyond
the 4G limit, I was talking about accessing the RAM within the 4G but
beyond where hardware sits on some machines, i. e. using non-contiguous
memory.

That is a hardware problem that you cannot solve with software. That is
why the memory remapping function were invented.

 

[John John - MVP]

John John - MVP wrote:



With device space I mean this:
http://msdn.microsoft.com/en-us/library/ms801998.aspx

Thanks for the link. In one of his blogs Mark Russinovich said that
"...problematic client driver ecosystem led to the decision for client
SKUs to ignore physical memory that resides above 4GB, even though they
can theoretically address it." My understanding about this is that
while (some of) the server versions can do this the whole point of
limiting memory access below 4GB on clients with PAE was to specifically
prevent drivers from playing in the upper memory arena. So now I'm not
sure what to think...

http://blogs.technet.com/markrussinovich/archive/2008/07/21/3092070.aspx
Mark's Blog : Pushing the Limits of Windows: Physical Memory

John