Intel Motherboards Using 82371SB PIIX3 Component

Updated: Tuesday, February 25, 1997

Description

Version 4.00.950 of Microsoft Windows* 95 may not recognize a non-compliant ATAPI device when configured as a master and connected alone on the secondary IDE port on Intel motherboards using the Intel 82371SB PIIX3 IDE controller. This can result in the ATAPI device (such as CD-ROMs) not being detected or being configured improperly. This is the retail version of Windows 95. OEM versions are not affected.

Root Cause

This problem has been isolated to CD-ROM drives that do not comply with the ATAPI specification. These IDE CD-ROMs may use an ATAPI interface chip that floats the IDE bus in between a "secondary slave identify" command and a subsequent read of the status register -- and potentially confusing the detection algorithm used by the Windows* 95 driver.

Although only one ATAPI device is connected as a master to the secondary IDE channel, Windows 95 detects another, non-existent device. When other functions try to use this ghost device, they fail and time out. As a result, the secondary channel is taken out of service, including the CD-ROM drive that was properly configured.

Users can detect a potential problem by using the Windows 95 Device Manager (click Start, Settings, Control Panel, double click on the System icon, then click on the Device Manager tab). The CD-ROM entry may potentially be missing and the secondary IDE controller under the Hard Drive Controller section will appear to be in conflict with another device or not working properly. Depending upon the CD-ROM in use, the drive may potentially be detected by Device Manager or be seen under My Computer. However, if the Secondary IDE Controller is shown to be in conflict, the CD-ROM may not work reliably.

Affected Products

This issue potentially affects all Intel motherboard products with the 82371SB component.

Workaround / Action

As a workaround, Intel recommends a system configuration consisting of a single IDE hard disk drive and a single CD-ROM drive as a master and slave on the primary IDE port. Contact Microsoft or Intel Customer Support for other workaround options that may be available.

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