Is there a legal way to force Windows XP 32bit to use all my memory?

[TYPICALHUMAN]

I'm looking for a trick that allows me to make use of available RAM. I've read on wikipedia that Windows 2000: Advanced Server can access 8 Gigabytes / Windows 2000 Datacenter Server 32GB. How?

 

[getochkn]

32bit's can't access more than 4GB. The math just doesn't work.

 

[TYPICALHUMAN]

Is there a logical explanation to why Windows Server can?

 

[bigpinkdragon286]

It's not a legality issue. It's just that, with 32-bit addresses, you simply can't address more than 4 GB. There are hacks and workarounds, but the simplest solution is actually to move to a 64-bit version of Windows. This still doesn't mean your software will use more than 2 GB. That's not just up to the platform you're running on, it's also up to how the software is written.

If for some reason, you must stick with XP, a 64-bit version of it was available. I'm not sure if you can still find copies available for purchase however.

 

[rgd1101]

https://technet.microsoft.com/en-us/library/cc961558.aspx
Up to 8 GB main memory on Intel PAE Systems

 

[ko888]

The original releases of Windows XP and Windows XP SP1 used PAE (Physical Address Extension) mode to allow RAM to extend beyond the 4 GB address limit. However, it led to compatibility problems with 3rd party drivers which led Microsoft to remove this capability in Windows XP Service Pack 2.

It wasn't removed from the server versions of the OS.

 

[bigpinkdragon286]

To further expound on what others have said, a quote from Microsoft:

"How graphics cards and other devices affect memory limits

Devices have to map their memory below 4 GB for compatibility with non-PAE-aware Windows releases. Therefore, if the system has 4GB of RAM, some of it is either disabled or is remapped above 4GB by the BIOS. If the memory is remapped, X64 Windows can use this memory. X86 client versions of Windows don’t support physical memory above the 4GB mark, so they can’t access these remapped regions. Any X64 Windows or X86 Server release can.

X86 client versions with PAE enabled do have a usable 37-bit (128 GB) physical address space. The limit that these versions impose is the highest permitted physical RAM address, not the size of the IO space. That means PAE-aware drivers can actually use physical space above 4 GB if they want. For example, drivers could map the "lost" memory regions located above 4 GB and expose this memory as a RAM disk."

 

[damric]

RAM Disk software can work around this.

 

[iamacow]

ANY 32bit app cannot address more than 4GB at once. There are work arounds in some apps to address more, but its still 4GB blocks.

 

[TYPICALHUMAN]

Thanks for your help!

 

[damric]

RAM Disk software can work around this.

See this on using RAM Disk as a memory extender.

http://www.asrock.com/feature/xfast/xfastram/index.asp

 

[damric]

Do go try this:

Take 32bit OS, 8GB of RAM. Set 4GB as RAM Disk. Set RAM Disk to Ready Boost.

This is not as good as 64bit, but it will utilize that RAM to speed up your system by giving you a faster disk cache.

It works. I've done it on plenty of older machines.

 

[getochkn]

And it does not allow the OS nor any programs to access more than 4GB of RAM, which is what the post is about, not making a RAM Disk.

 

[damric]

And it does not allow the OS nor any programs to access more than 4GB of RAM, which is what the post is about, not making a RAM Disk.

The OP isn't about a specific program addressing more than 4GB of RAM.

The OP is about utilizing more than 4GB of RAM on a 32bit OS, which a RAM Disk CAN DO, and plenty of us have done it.

Otherwise your answer is not wrong, you just aren't answering the right question. I'll put you a half star on the board anyway for effort

 

[BrianVS]

The Intel Pentium Pro manual for OS developers has good explanations of using more than 4GBytes of Physical memory, which is handled by the hardware. Use of "Segment Registers" allow single instructions to access memory in different regions, "kind of like" segment registers allow 16-bit real mode code to go beyond the 64KByte "tiny memory" model. The 4GByte limit for a Pentium Pro and newer is "kind of like" using the tiny memory model for an OS. I've never messed with this in XP, and with PharLap DOS- 4GBytes is more than enough for me. BUT- did have to get into this stuff when loading interrupt vector tables and mapping graphics card memory into FORTRAN common blocks via "Create and Map Physical Device page" 20 years ago.

I'm not sure what XP would do if you modified machine register CR4 while it's running... (HUMOR!)

 

[Dave_110]

32-bit processors just can't count that high so they can't address memory location past about 3.2 gig. In the simplest of terms. If you have only 4 bits, 1111 (decimal15), you can't count to 11111 ( decimal 31).

 

[BrianVS]

The address space on Pentium Pro and newer 32-bit processors is "segmented" using the ES,SS,CS,DS,FS,GS (from my old memory) Segment Registers to extend beyond the 32-bit program counter and data addresses. Addresses are used in 4GByte segments, but multiple segments can be used within one program. The machine specific CR4 register is used to enable more than 32-bits of physical address to be placed on the hardware address lines. Back to the 16-bit 8086 was able to address 1MByte of memory, which would require 20-bit addresses.