IDG logo

Advertise with InfoWorld

SiteMap News Test Center Opinions Forums Careers Stock Quote Subject Indexes About Us Search Subscribe Home [Window Manager]

January 13, 1997

Even more Windows 95B work-arounds exist for the bleeding edge

In several of my recent columns, I've described tricks and work-arounds needed for Windows 95B. This is a new version of Windows 95 (also called OSR2 and OEM Service Release 2) that is only available with the purchase of a hard drive or a complete system from an authorized OEM.

Microsoft does not plan to make Win95B available through software stores, and it has not released an upgrade kit. And if you receive a new computer on which the manufacturer has installed Win95B, but with the older FAT-16 file allocation table system still implemented, Microsoft provides no way for you to upgrade to the newer FAT-32, which stores files more efficiently.

(For details on Win95B's features and Microsoft's release plans, see my columns on Nov. 18, 1996, Nov. 25, 1996, Dec. 23/Dec. 30, 1996, and Jan. 6. A Web site with a lot of details on Win95B is located at

Many people are already using Win95B because OEMs are shipping systems with the new version installed.

One advantage of Win95B is that its FAT-32 allows a single hard-drive letter (partition) to be larger than 2GB, which is FAT-16's limitation. A single, large partition is very desirable for many applications.

You can determine whether you have Win95B by running the System control panel. It will show Version No. 4.00.950B or something similar to this. If so, some of the work-arounds for the "gotchas" described in last week's column and the following paragraphs may be useful to you.

If you don't have Win95B yet, you should save this column, because Win95B will become the standard version of Windows sooner or later.

  • Win95B supports a new feature called "IRQ steering." This feature allows Windows to catch messages sent to an IRQ (interrupt request) line and reroute them to the next available IRQ.

    This is most useful for PCI-bus devices in laptops with docking stations. As hardware is added and subtracted (when docking occurs), PCI devices can be dynamically reconfigured to work together. IRQ steering, by default, is not enabled in Win95B. For this reason, a PCI device may display "Error Code 29" for its status when viewed in the Device Manager.

    Assuming the docking device has not been physically disabled for some reason, this error may be corrected by enabling IRQ steering. To accomplish this in the System control panel, click Device Manager, expand the System Devices branch, click PCI Bus, click Properties, click IRQ Steering, then turn on the IRQ Steering check box.

  • The new FAT-32 file system theoretically supports drive partitions much larger than 2GB, but 8GB is currently the optimum size. This is because the FAT-32 file system stores files less efficiently (with more cluster waste) on partitions larger than 8GB.

    The 8GB size is also the absolute limit for IDE and SCSI hard-disk controllers that do not support Interrupt 13 extensions.

    Without support for these extensions, which implement a feature called Logical Block Addressing (LBA) that FAT-32 needs, you cannot create a partition larger than the default LBA limit of 7.9GB. A disk controller needs a BIOS chip upgrade if it doesn't support Interrupt 13 extensions.

  • Speaking of LBA, there are reports that FAT-32 won't work at all on some laptops and 486-class systems with BIOS chips that don't support LBA.

    This may be the primary reason that Microsoft won't provide support for FAT-32 but requires that all user support come from the OEM that sold equipment with Win95B loaded.

    Because Win95B is restricted to sales with new systems and drives, OEMs theoretically can test whether their systems are fully compatible with FAT-32 before they go ahead and implement it.

    I haven't yet uncovered a list of incompatible systems or a reliable test for LBA compliance. Stay tuned.

    Brian Livingston is the co-author of Windows 95 Secrets Gold and four other Windows books (IDG Books). Send tips to or fax: (206) 282-1248.

    Missed a column? Go back for more.

    Copyright © 1997 by InfoWorld Publishing Company


    Copyright © 2002. InfoWorld Media Group, Inc. is a member of complies with the ASME guidelines with IDG extensions For New media.