How Windows 95 Manages Virtual Memory

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The information in this article applies to:

• Microsoft Windows 98
• Microsoft Windows 95

SUMMARY

This article contains information and commonly asked questions about virtual memory in Microsoft Windows 95.

Windows 95 uses a dynamic virtual memory manager to handle swap file duties. You should use the default virtual memory settings whenever possible. However, if you have limited hard disk space you may want to set some of the virtual memory settings manually.

MORE INFORMATION

In order to provide more memory to applications than is physically present in the computer in the form of RAM, Windows 95 uses hard disk space to simulate RAM. The amount of RAM in the computer plus the size of the paging file (also known as the swap file) equals the total physical memory, or virtual memory, size. Windows 95 uses a dynamic paging file that remains at a size of 0K until it is needed. The paging file can grow to use all the available space on the hard disk if it is necessary. This is the default setting for the paging file. You should use this setting if possible.

If you have limited hard disk space, other applications may reduce the amount of virtual memory below that needed by Windows 95 and its applications. If this occurs, choose the "Let me specify my own virtual memory settings" option button on the Performance tab of the My Computer property sheet. You can use this option to set a minimum and maximum size for the paging file.

You can also choose to use no virtual memory. You should use this option only if there is enough RAM to meet all the needs of Windows 95 and the applications you run.

NOTE: The Disable Virtual Memory option is unavailable on computers with 8 MB of RAM or less.

QUESTIONS AND ANSWERS

1. Q. In Microsoft Windows version 3.x, a temporary swap file is slower

          than a permanent swap file. Will letting Windows 95 set my virtual
          memory slow down my computer?
   

       A. No. The temporary swap file in Windows 3.x has to switch between
          real mode and protected mode, slowing down the computer. As Windows
          95 runs only in protected mode, the swap file is as fast or faster
          than the permanent swap file in Windows 3.x.
   

2. Q. I compressed my hard disk with DriveSpace. Can I still select my

          own virtual memory settings? In Windows 3.x I cannot use a
          permanent swap file on a compressed drive.
   

       A. If your compressed drive is supported by a protected-mode driver,
          it is better to use the compressed drive for the paging file. If
          the compressed drive is not supported by a protected-mode driver
          then you must place the paging file on the host drive.
   

3. Q. How can I determine whether my compressed drive is supported by a

          protected-mode driver?
   

       A. At this time there are protected-mode drivers only for DoubleSpace
          and DriveSpace compressed drives. You can also check the IOS.INI
          file (if it exists) in the Windows directory to see which drives
          require real-mode support.