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-
- PATCH87.DOC File
-
- Notes on patching MS-DOS(R) Version 3.20
-
- (C) Copyright Microsoft Corporation, 1988
-
-
- Version 3.20 of MS-DOS(R) contains a bug that can cause unexpected results in
- programs that use floating-point math. This file explains how to eliminate
- that problem by using PATCH87.EXE, a program included in this release.
-
- Note that IBM(R) PC-DOS 3.20 contains another, different floating-point bug.
- The README.DOC file for this release tells you where to find more information
- about installing a patch for that bug. If you use any version of DOS 3.20
- other than IBM PC-DOS 3.20 or MS-DOS 3.20, contact your hardware manufacturer
- to determine whether the problem exists in your version.
-
-
- Do I Need to Use This Program?
- ------------------------------
- You do not need to read any further unless your system has ALL of the following
- characteristics:
-
- 1. You use MS-DOS version 3.20.
- 2. You boot from a hard-disk drive.
- 3. Your system has a math coprocessor (for instance, an 8087 chip).
- 4. You run programs that use floating-point math.
-
- For systems that satisfy all of the preceding conditions, you may be able to
- eliminate floating-point math problems by installing a small patch in DOS. If
- you are not sure whether you need the patch, perform the following steps:
-
- 1. Copy the program PATCH87.EXE (included in this release) to the root
- directory of your hard-disk drive.
-
- 2. Reboot your system from the hard disk and DO NOT PERFORM ANY FLOPPY-
- DISK OPERATIONS after rebooting. It is very important that you avoid
- floppy-disk I/O after rebooting, since that will affect the reliability
- of the diagnostic test that you are about to perform.
-
- 3. If necessary, use the CD command to move to the root directory of your
- hard-disk drive.
-
- 4. Run the PATCH87.EXE program by entering this command at the DOS prompt:
-
- PATCH87
-
- The program performs a diagnostic test on your system to determine
- whether it needs the DOS patch, and, if the patch is needed,
- whether it can be performed successfully.
-
- 5. Follow the procedure described in the next section if the program
- tells you that you need to install the DOS patch, and that it can
- be done.
-
- NOTE: The floating-point problem has been eliminated in versions of
- MS-DOS higher than 3.20. This includes MS-DOS versions 3.21 and 3.30.
-
-
-
- If You Need to Install the Patch
- --------------------------------
- If you performed the preceding test and determined that you should install the
- DOS patch on your system, perform the following steps:
-
- 1. Format a blank floppy disk. (Do NOT use the /s formatting option to
- transfer system files to the disk.)
-
- 2. Use the SYS command to copy IO.SYS and MSDOS.SYS from the root
- directory of your hard disk to the new floppy disk. For instance, if
- you boot from drive C:, you would enter the following commands:
-
- C:
- SYS A:
-
- 3. Use the COPY command to copy COMMAND.COM and SYS.COM to the same
- floppy disk.
-
- 4. Use the COPY command to copy the program PATCH87.EXE (included in this
- release) to the same floppy disk.
-
- 5. Change the current drive and directory to the floppy disk, by entering
- the following command:
-
- A:
-
- 7. Install the DOS patch by entering the following command:
-
- PATCH87 /F
-
- WARNING: If you experience any disk errors during steps 2 through 7,
- do NOT proceed with step 8. Reboot from your hard disk and repeat the
- entire process.
-
- 8. If you have not experienced any errors, use the SYS command to transfer
- the files IO.SYS and MSDOS.SYS from the floppy disk back to your hard
- disk. For instance, if the boot directory of your system is the root
- directory of drive C:, you would enter the following command at the DOS
- prompt:
-
- A:
- SYS C:
-
- This installs the DOS patch.
-
- 9. Reboot the system.
-