Difficulties Using AMD K6-2 or Athlon Central Processing Unit (192841)


The information in this article applies to:

  • Microsoft Windows 95
  • Microsoft Windows 95 OEM Service Release 2
  • Microsoft Windows 95 OEM Service Release 2.1
  • Microsoft Windows 95 OEM Service Release 2.5
This article was previously published under Q192841

SYMPTOMS

When you start your Windows 95-based or Windows 95 OEM Service Release- based computer that is using an AMD K6/2 (350MHz or faster), or an AMD Athlon (1.1GHz or faster), you may receive one of the following error messages:
  • Device IOS failed to initialize. Windows Protection Error. You must reboot your computer.
  • Windows Protection Error. You must reboot your computer.
  • While initializing device IOS: Windows protection error.
NOTE: This problem is very intermittent on the K6/2 at 350 MHz, but occurs more often at higher speeds. This problem can also occur when you start your computer in Safe mode.

CAUSE

The first error message is a result of a divide exception in Ios.vxd; the second is due to a similar error within Esdi_506.pdr or Scsiport.pdr.

The original released versions of the files listed in the "Resolution" section of this article contain initialization timing loops that do not execute properly on the indicated processors at speeds of 350 MHz and faster. Note that this problem is due to limitations of the software algorithms, and is not indicative of a problem with the processor itself, which is functioning properly.

RESOLUTION

The AMD-K6-2 update has been revised to incorporate a newer version of Vfbackup.vxd file. For information about this update, please see the following article in the Microsoft Knowledge Base:

234259 Revision To AMD K6-2/350 Central Processing Unit Update

A supported fix that corrects this problem for Microsoft Windows 95 OEM Service Release versions 2, 2.1, and 2.5 is now available from Microsoft, but has not been fully regression tested and should be applied only to computers experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you use the next release of Windows.

To resolve this problem immediately, visit the following Microsoft Web site:

http://www.microsoft.com/windows95/downloads

Scroll down to the Service Packs section and then click the link to download the Windows 95 Update for AMD-K6-2/350.

This issue is resolved by the following updated files for Windows 95 OSR 2 and OSR 2.1: 
   Date      Time     Version    Size           File name
   ---------------------------------------------------------
   09/04/98  11:18am  4.00.1118  24,426 bytes   Esdi_506.pdr
   08/03/98  11:13am  4.00.1113  25,249 bytes   Hsflop.pdr
   09/04/98  11:12am  4.00.1112  23,158 bytes   Scsiport.pdr
   01/15/97  11:12am  4.00.1112  59,153 bytes   Cdfs.vxd
   01/15/97  11:12am  4.00.1112  18,809 bytes   Disktsd.vxd
   01/15/97  11:12am  4.00.1112   9,955 bytes   Int13.vxd
   09/04/98  11:13am  4.00.1113  68,962 bytes   Ios.vxd
   01/15/97  11:12am  4.00.1112  18,197 bytes   Vfbackup.vxd
In addition, the following updated file is needed for OSR 2.1: 
   Date      Time     Version    Size            File name
   --------------------------------------------------------
   12/04/98  12:13pm  4.00.1213  111,678 bytes   Ntkern.vxd
NOTE: This fix does not correct the problem for the retail version of Windows 95. In addition, versions of the Amdk6upd.exe update dated "09/18/98 11:00am" do not replace the Ntkern.vxd file in OSR 2.1 and OSR 2.5. To determine the version of the Ntkern.vxd file installed on your computer, right-click the Ntkern.vxd file in the Windows\System\Vmm32 folder, click Properties, and then click the Version tab. If the version number is not 4.03.1213, you should obtain and install a new version of the update, as described below. Note that the version of the original Ntkern.vxd file is 4.03.1212.

To install this update, follow these steps:
  1. Download the Amdk6upd.exe file to a floppy disk. Download the file from another computer, if necessary.
  2. Restart your computer. When you see the "Starting Windows 95" message, press the F8 key, and then choose Safe Mode from the Startup menu.
  3. If your computer starts in Safe mode, skip to step 6. If you cannot start Windows, continue with step 4.
  4. Restart your computer. When you see the "Starting Windows 95" message, press the F8 key, and then choose Command Prompt Only from the Startup menu.
  5. At the c:\ prompt, type win /d:m to start Windows in Safe mode.
  6. Insert the floppy disk containing the Amdk6upd.exe file you downloaded in step 1, and then use Windows Explorer or My Computer to double-click the file.
  7. Follow the instructions on the screen to install the update.
The following file is available for download from the Microsoft Download Center:

Download Amdk6upd.exe now



For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

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STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows 95 and OEM Service Release versions 2, 2.1, and 2.5.

This issue is resolved in Microsoft Windows 98.
Modification Type:MinorLast Reviewed:9/22/2005
Keywords:kbHotfixServer kbQFE kbdownload kbenv kberrmsg kbfile kbgraphxlinkcritical kbprb KB192841
©2004 Microsoft Corporation. All rights reserved.