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What is a Swap file

A “Swap file”, “paging file” or “Virtual Memory” refers to storage space on hard drives that Windows allocates for itself and other applications to use when actual physical memory (RAM) is no longer available.

Windows generates a file (pagefile.sys in XP for example) and reserves storage space.

With the implementation of a swap file, developers had the freedom to write applications without as much fear of the physical RAM limitation, Windows itself had the ability to “swap” parts of inactive data that were loaded into RAM, off to the hard drive to make room for whatever application was demanding the extra memory allocation.

Over the past decade of software and hardware evolution, the needs and characteristics of the swap file have changed quite significantly.

Windows for Workgroups (Win 3.11) – Aspects of DOS still prevailed and the Windows O/S of the day had severe memory management limitations. Programming of applications overcame the 640k DOS limitation and page into extended/expanded physical memory was still being mastered. Although virtually no applications as such required the use of this swapping scheme yet, the Operating system itself made use of it to a certain degree.

Windows 95 made a large step forward in O/S design, but still retained several memory management limitations. Applications written for Windows 95, as well as the Operating system itself, began to integrate swap file usage to maximize application productivity. The problems at this stage of history had more to do with hardware limitations. At the time a 500MB hard drive and 16MB of RAM were considered “Powerful”. Memory was terribly expensive and using a small area of hard drive space, though limited, was still the best solution at the time to providing more “workspace” for open applications.

Windows 98 was released, and essentially was nothing more than an enhanced, and updated Windows 95. A lot of the original characteristics of the “9x” family were transferred directly to the new operating system. Hardware improvements back then made very significant differences in the average users PC performance (unlike today).

With hardware advancing so fast, and the standard sizes of memory and hard drive space increasing, the default memory configurations provided by the Operating system were no longer considered optimal as they were designed for older hardware levels.

At this stage, advanced users began to experiment with configurations for memory management to optimize their personal systems.

Windows ME – this was the last stop in the “9x” family line. It was intended to be the “best of both worlds” and an O/S to hold people until the release of the then delayed Windows 2000, NT based O/S. Unfortunately Windows ME proved to be the worst of both worlds, being plagued by bad drivers, incompatibilities, and memory leaks.

Windows 2000 finally arrived. This operating system was based on the NT structure of operating system but with more user-friendly functionality. Windows 2000 did not suffer from the memory limitations of the 9x family since it used the same memory management structure of NT 4.0. It became a hit in the corporate world as it was more secure and stable than any 9x system but avoided the crudeness of its earlier NT releases. With the understanding of past limitations in swap file management of the 9x based operating systems, Microsoft provided easier user level control and configuration of the swap file in the “NT” family. This was an enormous asset since more complex applications today are written and often require massive amounts of resources (including many of our newer games).

However with the thought that most initial adopters of Windows 2000 would be companies upgrading existing machines, MS once again opted to maintain a “modest” default memory management configuration, understanding that most hardware would be from the pre-2000 era. Advanced users with abnormal memory requirements, levels, and hard drive space, chose to experiment with memory management once again and discovered performance gains could be made with minor modifications to suit their personal PC.

Windows XP is essentially an enhanced, more feature rich version of Windows 2000, with one large exception to the home user, it played games very well. Before the release of XP, Windows 98 was the most popular O/S for the gamer. With this ability and the benefit of better memory management, XP soon became an extremely popular O/S for the gamer. Today you will find that most new and demanding games run best on XP. Developers know and understand the memory management benefits of XP and exploit them. Most memory tweaks from Windows 2000 carried over to XP.

Thanks for reading this blurb about swap files,

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