Microsoft KB Archive/139987

= Cannot Access CD-ROM Drive on Acer Pentium PCI using Cmd640x =

Article ID: 139987

Article Last Modified on 1/19/2007

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APPLIES TO


 * Microsoft Windows 95
 * Microsoft Windows 98 Standard Edition

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This article was previously published under Q139987



SYMPTOMS
After you upgrade an Acer computer from an earlier version of Windows to Windows 95, the following problems may occur:


 * The CD-ROM drive is not detected.
 * 32-bit disk and file access is not available.

These symptoms may also occur when you upgrade an Acer 91.AA260 computer to Windows 98.



CAUSE
These problems can occur if the CD-ROM drive is connected to a CMD CSA- 6400E PCI IDE controller. The Cmd640x.sys real-mode driver on Acer computers is designed to work in Windows 3.1 and does not work in Windows 95.

If you use the CMD 6400 PCI controller protected-mode driver CMD CSA- 6400E, 32-bit disk and file access is functional but the CD-ROM drive is not detected.

If you use the CMD 6400 PCI controller real-mode driver Cmd640x.sys, the CD-ROM drive is detected, but 32-bit disk and file access is not available.

All Acer computer systems with a part number starting with 91.AA043 or 91.AA260 using the CMD CSA-6400E PCI IDE controller and a Maxtor 7546AT hard disk running Windows 95 exhibit this behavior.



RESOLUTION
To correct this problem, load the Windows 95 version of the CMD CSA- 6400E PCI IDE driver. Download the self-extracting file Cmdwin95.exe from Acer's FTP server (ftp.acer.com), or from Acer's World Wide Web site (www.acer.com/aac/win95/upgrades/ftp.htm). For additional information, please contact Acer Technical Support.

You may be able to resolve this issue using the following steps:
 * 1) Click Start, point to Settings, and then click Control Panel.
 * 2) Double-click System, and then click the Device Manager tab.
 * 3) Double-click Hard Disk Controllers, and then double-click CMD 640 Bus Master Controller.
 * 4) On the Settings tab, click Both IDE Channels Enabled in the Dual IDE Channel Settings box, click OK, and then click OK.

Additional query words: hwcds

Keywords: kbhardware kbprb KB139987

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