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

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|                                                                     |
| 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.             |
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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
(floating point unit), a part of the Intel Pentium chip that performs
elaborate calculations. Intel is aware of this problem.

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. Copy P5PATCH.COM to your Microsoft Excel directory.
   To do this, type in the following and press ENTER

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

   where <source> is the directory containing P5PATCH.COM <destination> is
   your Microsoft Excel directory. For example, if P5PATCH.COM is in
   C:\DOWNLOAD and and your Microsoft Excel directory is C:\EXCEL, type
   the following command:

      copy c:\download\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:

      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 in your workbook
---------------------------------------

Once you have installed the patch, do the following to force your workbook to
be recalculated.

1. From the Tools menu, choose Options.

2. In the Options dialog box, select the Calculation tab, and then choose 
   Calc Now.


