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How can I extend the memory usage on my 32 bit Windows machine?


The HuygensSoftware for 64 bit Windows (XP, Vista, and 7) can address all available memory.

Generic 32 bit Windows installations limit the user applications to 2 GB of memory. However, on some windows platform there is a possibility to extend the user address space to 3GB by adding the /3GB to the boot options in the boot.ini file. The HuygensSoftware can take full advantage of the extra 1 GB memory space.

Please Note: Wrong modifications of the boot configuration might result with unbootable system. Please exercise caution while committing such changes!!!


See the following articles on Microsoft's support site:

See also demystifying the 3GB switch(external link).

According to the Microsoft support site, the following 32 bit platforms can support 3GB memory user space:
  • Windows 2000 Advanced Server
  • Windows 2000 Datacenter Server
  • Windows 2003 server
  • Windows XP Professional
  • Windows NT Server Enterprise Edition on Intel architecture.

Basically, the way to insert the /3GB switch is to edit the files C:\boot.ini by adding one more boot line option which contains the /3GB flag.

For example, if the original boot.ini is:
[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="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect


you should add one more line that includes the /3GB option, i.e.

[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="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise 3GB" /noexecute=optout /fastdetect /3GB


Please Note: This is an example that should NOT be taken literally. The idea is to add one more line to the list of operating systems, by duplicating the main installation description but adding the /3GB option to it, and giving it a new name.


Please refer to the Microsoft support page on the boot.ini file in: http://support.microsoft.com/kb/314081(external link)

In order to view the boot.ini file on Windows XP you should open C:\ in the file browser, Choose: Tools→Folder Options. In the "Folder Options" window choose the "View" tab. Browse in the "Advanced Settings" list to "Hidden files and folders" and choose "Show hidden files and folders". Click "Apply", and you will find the boot.ini file in directory C:\.

Please make sure that there is enough virtual memory in your system. This is typically configured in: Control Panel → System → Advanced → Performance → Advanced → Virtual Memory → Change.

Keywords: memory boot.ini /3GB
Categories: Faq Platforms, Huygens Faq, Imported Faqs
Platforms: Windows
Related products: HuEss HuPro HuScript FreeSFP