Programming Guide for 64-bit Windows

Microsoft has released 64-bit versions of the Windows operating system. 64-bit Windows was designed with compatibility in mind. Developers can ensure that their existing 32-bit applications run well under 64-bit Windows or take advantage of the benefits of 64-bit Windows by migrating their applications.

Benefits of 64-bit Windows

A 64-bit operating system supports far more physical memory than a 32-bit operating system. For example, most 32-bit Windows systems support a maximum of 4 gigabytes of physical memory, with up to 3 gigabytes of address space for each process, while 64-bit Windows supports up to 2 terabytes of physical memory with 8 terabytes of address space for each process. The increased physical memory includes the following benefits for applications:

  • Each application can support more users. All or part of each application must be replicated for each user, which requires additional memory.
  • Each application has better performance. Increased physical memory allows more applications to run simultaneously and remain completely resident in the system's main memory. This reduces or eliminates the performance penalty of swapping pages to and from disk.
  • Each application has more memory for data storage and manipulation. Databases can store more of their data in the physical memory of the system. Data access is faster because disk reads are not necessary.
  • Applications can manipulate large amounts of data easily and more reliably. Video composition for motion picture work requires 64-bit Windows for this reason. Modeling for scientific and financial applications benefits greatly from memory-resident data structures that are not possible on 32-bit Windows.

There are also important benefits for businesses:

  • Increased productivity. Knowledge workers can spend their time thinking and producing, rather than waiting for the software to finish its tasks.
  • Lower cost of ownership. Each server can support larger numbers of users and applications, so your business will require fewer servers. This translates directly into less management overhead—one of the highest costs in any computing environment.
  • New application opportunities. New applications can be designed without the barriers imposed by 32-bit Windows. New graphics applications will make work easier and more enjoyable. Data-intensive tasks that are impossible today can be done with 64-bit Windows.

In this Section