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Microsoft KB Archive/171284

From BetaArchive Wiki

Problems Enumerating CardBus Devices with No Free IRQs


The information in this article applies to:

  • Microsoft Windows 95 OEM Service Release, versions 2, 2.1


When you are running Windows 95 on a computer with CardBus slots, you may experience the following symptoms:

  • When multiple PC Cards are installed and the computer is started, Windows may not start and you may receive the following error message:

    While initializing ... device V86MMGR: Insufficient memory to initialize Windows.

  • If Windows is running with one PC Card inserted, the computer may become unresponsive for several minutes when you insert another PC Card. When the computer returns from this busy state, Device Manager Reports the new card as disabled because of a resource conflict (code 12).


These symptoms can occur if there are not enough available IRQ lines for all the installed devices.


This issue is resolved by the following updated file for Windows 95 OSR2, and later versions of this file:

   VMM.VXD  version 4.00.978  dated 6/12/97  408,096 bytes 

To work around this issue, make more IRQ resources available by disabling a device (such as a COM port or LPT port). Such devices can typically be disabled in Device Manager.


Microsoft has confirmed this to be a problem in Microsoft Windows 95 OEM Service Release 2 (OSR2). An update to address this problem is now available, but is not fully regression tested and should be applied only to computers experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft does not recommend implementing this update at this time. Contact Microsoft Technical Support for additional information about the availability of this update.

This issue is resolved in Microsoft Windows 98.


If there are not enough available IRQ lines, there is no configuration that allows all devices to be active without a resource conflict. A device must be removed or disabled to free an IRQ line and allow the remaining devices to be configured successfully.

The update causes Windows to more quickly recognize that it cannot resolve the resource conflict. The new device is disabled as before, but more quickly.

Note that these symptoms may appear more readily with certain specific PC Card devices that use more than one IRQ line or cannot share IRQ lines with other devices.

For additional information about issues resolved by updates to this component, please see the following articles in the Microsoft Knowledge Base:

Q179897 Memory Management Problems on Computers with Pentium Processors

Q165405 Computer with NeoMagic Display Hangs When PC Card Is Inserted

For additional information about Windows 95 updates, please see the following article in the Microsoft Knowledge Base:

Q161020 Implementing Windows 95 Updates

Additional query words: pccard card bus hang

Keywords : kbenv kbhw osr2 win95
Issue type :
Technology : kbWin95search kbOPKSearch kbWin95OPKOSR2 kbWin95OPKOSR210

Last Reviewed: January 31, 2001
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