How to Test for a Faulty Pentium FPU

 Last reviewed: October 6, 1997
Article ID: Q101467
The information in this article applies to:
  • Microsoft Excel for Windows, versions 4.0, 4.0a, 5.0, 5.0c

SYMPTOMS

If you are using Microsoft Excel on a computer that contains an Intel Pentium processor, you may receive unexpected results when you perform mathematical operations that involve dividing certain combinations of numbers.

CAUSE

This problem is caused by an error in the FPU (floating point unit), a part of the Intel Pentium chip that performs elaborate calculations. Intel is aware of this problem.

To test if the FPU in the Pentium chip in your computer has this problem, use any of the following methods:

Method 1: Using the Windows Calculator located in the Accessories group in 

          Program Manager, do the following:

          a. Enter the value 5505001. Press the division button (/).

          b. Enter the value 294911. Press the equal sign button (=).

          The correct answer is 18.66665197297. If you do not receive this
          value, for example if you receive the value 18.6660009291, your
          Pentium computer has a faulty FPU.
Method 2: Using a worksheet in Microsoft Excel, do the following: 

          a. On a new worksheet, enter the following:

                A1: 1
                A2: 3221224323
                A3: =A1/A2
                A4: =A3*A2

          b. Select Column A. From the Format menu, choose Column, and then
             choose AutoFit Selection.

          If the value returned in cell A4 is NOT 1, your Pentium computer
          has a faulty FPU.
Method 3: Obtain the Application Note "Pentium Floating Point Unit (FPU) 
          Patch" (WE1136). You can run the patch provided in this
          application note to determine whether or not your computer has
          this problem.

To Obtain the Pentium FPU Patch

The quickest way to obtain the Pentium FPU patch is to download it from one of the online services listed below. The size of the WE1136.EXE file is approximately 16K. If you are unable to download the patch, see the instructions for alternative ways to obtain it.

The following file(s) are available for download from the Microsoft Software Library: 

 ~ WE1136.EXE (size: 16359 bytes)
For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services
If you are unable to access the source(s) listed above, you can have this Application Note mailed or faxed to you by calling Microsoft Product Support Services Monday through Friday, 6:00 A.M. to 6:00 P.M. Pacific time at (425) 635-7070. If you are outside the United States, contact the Microsoft subsidiary for your area. To locate your subsidiary, see the Microsoft World Wide Offices Web site at: 

   http://www.microsoft.com/worldwide/default.htm
NOTE: This patch will work on all international versions of Microsoft Excel for Windows.

For additional information, please see the following article(s) in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q123783
   TITLE     : XL AppNOTE: "Pentium Floating Point Unit Patch"

Additional query words: 7.00 4.00 4.00a 5.00 5.00c
Keywords : xlwin kbfile kbother kbtshoot
Version : 4.x 5.00 5.00a 7.00
Platform : WINDOWS

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: October 6, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.