WFWG: Network Applications Unable to Find NetBIOS

• Microsoft Windows for Workgroups version 3.1

SYMPTOMS

If you are using Windows for Workgroups, some MS-DOS-based network applications that check for the presence of NetBIOS may not be able to find it.

WORKAROUND

To allow the application to find NetBIOS present and operate correctly, replace the NET START line in your AUTOEXEC.BAT file with the following:

   NET START NETBEUI

MORE INFORMATION

Some MS-DOS applications check for NetBIOS by examining the interrupt vector table for the 0x5C entry. If the entry is the default (0 or segment F000), then these applications assume the interrupt is not hooked and NetBIOS is not present. Microsoft Diagnostics (MSD) is an example of such an application. It returns NetBIOS not detected in the NETWORKS section even if the NETBEUI protocol is running.

The protected mode transport (VNB.386), provided with Windows for Workgroups, may not reflect a change to the interrupt vector table. Therefore, when an MS-DOS-based application examines the vector table it may not find NetBIOS present even when it is present. If you use the real-mode transport (for example, by typing NET START NETBEUI at the command prompt), then the vector table check will be successful.

Changing NET START command line to NET START NETBEUI means that the real mode transport is used instead of the protected mode transport; the protected mode redirector is still loaded, which leaves more memory available for MS-DOS applications.

For more information on NetBEUI and NetBIOS, query on the following words in the Microsoft Knowledge Base:

   netbeui and netbios