Excel AppNote: Pentium Floating Point Unit Patch (WE1136)

ID: Q123783

The information in this article applies to:

Microsoft Excel for Windows, versions 4.0, 4.0a, 5.0, 5.0a, 5.0c

SUMMARY

The "Pentium Floating Point Unit (FPU) Patch" (WE1136) Application Note is now available from Microsoft Product Support Services (PSS). This application note contains a patch that you can use to test for a faulty FPU and to disable the FPU in your computer when you use Microsoft Excel.

To Obtain This Application Note

The following file is 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

MORE INFORMATION

The Text of We1136

  Microsoft(R) Product Support Services Application Note (Text File)
          WE1136: PENTIUM(R) FLOATING POINT UNIT (FPU) PATCH

                                                  Revision Date: 12/94
                                                       1 Disk Included

The following information applies to Microsoft Excel for Windows(TM), version 4.0, 4.0a, 5.0, 5.0a, 5.0c.

 ---------------------------------------------------------------------
| INFORMATION PROVIDED IN THIS DOCUMENT AND ANY SOFTWARE THAT MAY     |
| ACCOMPANY THIS DOCUMENT (collectively referred to as an Application |
| Note) IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER      |
| EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED      |
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| PURPOSE. The user assumes the entire risk as to the accuracy and    |
| the use of this Application Note. This Application Note may be      |
| copied and distributed subject to the following conditions:  1) All |
| text must be copied without modification and all pages must be      |
| included;  2) If software is included, all files on the disk(s)     |
| must be copied without modification (the MS-DOS(R)  utility         |
| diskcopy is appropriate for this purpose);  3) All components of    |
| this Application Note must be distributed together;  and  4) This   |
| Application Note may not be distributed for profit.                 |
|                                                                     |
| Copyright (C) 1994 Microsoft Corporation.  All Rights Reserved.     |
| Microsoft and MS-DOS are registered trademarks and Windows and      |
| Windows NT are trademarks of Microsoft Corporation. Intel and       |
| Pentium are registered trademarks of Intel Corporation.             |
 ---------------------------------------------------------------------

Introduction

If you are using Microsoft Excel on a computer that contains an Intel(R) Pentium processor, you may receive unexpected results when you perform mathematical operations that involve dividing certain combinations of numbers. This problem is caused by an error in the FPU, a part of the Intel Pentium chip that performs elaborate calculations. Intel is aware of this problem.

The disk included with this Application Note contains a patch for use with Microsoft Excel for Windows version 4.0, 4.0a, 5.0, 5.0a, or 5.0c. The patch allows you to do the following:

Test whether the FPU in your computer is faulty.
Prevent Microsoft Excel from using the built-in FPU.

After you install the patch, Microsoft Excel will handle all math operations as though there were no FPU in your computer. Because the FPU is disabled in Microsoft Excel, any calculation errors that you received as a result of the FPU will be corrected.

   NOTE: This patch works with Microsoft Excel versions 4.0, 4.0a,
   5.0, 5.0a, and 5.0c (including all non-English language versions).
   The patch does not work with Microsoft Excel version 5.0 for
   Windows NT(TM).

To copy the patch to your hard disk drive

1. Quit Microsoft Excel.

2. Insert the enclosed WE1136 disk in your floppy disk drive.

3. At the MS-DOS prompt, type the following and press ENTER

      copy <drive>:\p5patch.com <destination>

   where <drive> is the floppy disk drive containing the WE1136 disk
   and <destination> is your Microsoft Excel directory. For example,
   if the WE1136 disk is in drive A and your Microsoft Excel directory
   is C:\EXCEL, type the following command and press ENTER:

      copy a:\p5patch.com c:\excel

To test for a faulty FPU

1. At the MS-DOS prompt, change to the drive that contains your

   Microsoft Excel directory. For example, if your Microsoft Excel
   directory is on drive C, type the following command and press
   ENTER:

      c:

2. Change to your Microsoft Excel directory. For example, if your

   Microsoft Excel directory is C:\EXCEL, type the following and press
   ENTER:

      cd \excel

3. Type the following and press ENTER to determine whether your

   Pentium computer has a faulty FPU:

      p5patch

   The patch will return a message stating whether your Pentium
   computer has a faulty FPU.

To run the Pentium FPU patch

At the MS-DOS prompt, type the following and press ENTER:

   p5patch /p

NOTE: The FPU is now disabled for Microsoft Excel. If you want re-enable the FPU for Microsoft Excel, you can remove the patch. To remove the patch, type the following and press ENTER:

      p5patch /u

To update the formulas on your worksheet

After you have installed the patch, do either of the following to update the formulas on your worksheet:

To force your entire worksheet to be recalculated, press CTRL+ALT+F9.
```
    -or-
```

To recalculate a single cell, or a range of cells on your worksheet, do the following:

Note that the following method is not recommended if you are using array-type formulas. Replacing the equal sign (=) in such formulas will require that you re-enter any array formulas as arrays.

    1. Select the cell, or cells, on the worksheet that you want to
       update.

    2. In Microsoft Excel 5.0, choose Replace from the Edit menu. In
       Microsoft Excel version 4.0, choose Replace from the Formula
       menu.

    3. In the Find What box, type =. In the Replace With box, type =.
       In Microsoft Excel version 5.0, clear the Find Entire Cells Only
       check box if it is selected. In Microsoft Excel version 4.0,
       under Look At, select the Part option.

    4. To recalculate a single cell, choose the Replace button. To
       recalculate a range of cells, choose the Replace All button.

Additional query words: 4.00 4.00a 5.00 5.00a 5.00c p5 numeric coprocessor co-processor processor floating-point math

Keywords          : kbfile kbdta xlwin 
Version           : WINDOWS:4.00,4.00a,5.00,5.00a,5.00c
Platform          : WINDOWS
Issue type        : kbinfo

Last Reviewed: September 4, 1998