1. Potential Advantages of a 64-bit Operating System
A 64-bit architecture offers several benefits. The primary advantage is the ability to make use of additional computer memory. A computer running a 32-bit Windows operating system is limited to using a maximum of 4 GB of RAM. Such a limitation does not exist with 64-bit architecture. Windows 7 and 64-bit Windows Vista have a maximum memory limit of between 8 and 192 GB, depending on the operating system edition (Home, Professional, Enterprise). For more information about memory limitations for different versions of Windows, refer to the Memory Limits for Windows Releases document on the Microsoft web site.
A 64-bit architecture provides performance improvements for users running applications on 64-bit hardware because the operating system can take advantage of more physical memory than a 32-bit system is capable of doing. More available memory can increase system performance by eliminating the need to swap processes in and out of page files stored on hard drives, which is a much slower memory storage device than physical memory and cache.
In addition to increased physical memory, additional registers on a 64-bit processor can increase execution speed of applications by as much as 20 percent.
2. Considerations Before Switching to a 64-bit Operating System
Although there are benefits to using a 64-bit operating system, it might not be feasible or optimal to make the transition to a 64-bit system if much of the current software available is intended for use on 32-bit systems. A move to a 64-bit architecture means running a different Windows kernel and thus any driver installed must be compatible with the 64-bit architecture. The majority of National Instruments software and drivers are 64-bit compatible. However, it is important to understand the difference between compatibility with a 64-bit operating system and native 64-bit support that can take full advantage of the architecture and available memory.
In order to clarify the difference, National Instrument drivers can be broken down into two different components: User-Mode and Kernel-Mode. The architecture of the Kernel-Mode component of the driver matches the architecture of the operating system. The architecture of the User-Mode component of the driver does not have to match the operating system. Therefore, any software running in User-Mode can be developed as 32-bit or 64-bit. The Kernel-Mode component of most National Instruments drivers is capable of running on either a 64-bit or 32-bit operating system. Although, only certain National Instruments drivers have a 64-bit User-Mode component to the driver. Therefore, even though a driver can operate on a 64-bit version of Windows, the driver might not fully take advantage of the 64-bit architecture.
When a driver uses a different User-Mode architecture than Kernel-Mode architecture, a software layer converts the 32-bit architecture to 64-bit. This conversion requires processing time and resources. Windows 7 and Windows Vista provide this software layer in a subsystem called Windows-on-Windows (WOW64) included in the operating system. This subsystem allows 32-bit applications to run on the 64-bit environment at the expense of performance.
3. Windows-on-Windows 64-bit (WOW64)
The Windows-on-Windows subsystem is designed to allow the conversion of 32-bit Windows applications to the 64-bit environment. This subsystem handles many of the structural changes that must take place because of differences in the operating system architectures. The primary purpose of WOW64 is to create a 32-bit environment that provides the interfaces required to allow 32-bit Windows applications to run unmodified on the 64-bit system. Even though this is a relatively light-weight layer within the Windows operating system, it can cause some performance degradation. Therefore, it is more efficient to use 32-bit applications on a 32-bit operating system, as this does not require the Windows-on-Windows conversion.
4. National Instruments 64-bit Support and Recommendations
Most National Instruments drivers support both 32-bit and 64-bit architectures. Additionally, beginning with the release of LabVIEW 2009, separate 32-bit and 64-bit software versions are available. These separate versions only are available for the English version of LabVIEW Base, Full, or Professional software and do not include modules or toolkits, with the exception of the NI Vision module. LabVIEW 2009 64-bit is not compatible with other National Instrument software products such as LabVIEW RT, LabVIEW FPGA, NI TestStand, and LabVIEW toolkits. National Instruments plans to continue to monitor demand and prioritize this migration for other products in the future. In addition to LabVIEW 2009, 64-bit versions are available for the following software: NI-VISA, NI-GPIB, NI-DAQmx, and NI-IMAQ.
To see a complete list of compatible software, refer to National Instruments Product Compatibility for Microsoft Windows 7.
Use the following illustration to determine the best Windows architecture to optimize the performance of your applications.
You can download the 64-bit version of LabVIEW 2009 via the Service Resource Center on the National Instruments web site.