PATCHES FOR 'CP/M-86 FOR THE IBM'

   'CP/M-86 For The IBM' is an operating system from the early
   1980s, and was designed for 1980s hardware.  Because of this,
   problems can arise when attempting to run CP/M-86 on 21st
   century computers.

   For instance, 'CP/M-86 For The IBM' -- as originally released
   by Digital Research -- will not boot or run on a 286 or higher
   computer.  The 'AT Patch,' below, rectifies this deficiency.

   Also, 'CP/M-86 For The IBM' natively displays only 20th century
   dates.  The 'Year 2000 Patch,' below, will permanently fix this
   problem.

   NOTE: These patches are specific to 'CP/M-86 For The IBM PC and
   IBM PC XT, Version 1.1.'  They will NOT work with any other
   permutation of CP/M-86.

   'Patching' should always be done to a -copy- of the CPM.SYS
   file, and never to the file on the original system disks.

   As is always the case with this kind of 'free' information,
   there are NO guarantees whatsoever.  If you choose to use this
   information, you do so entirely at your own risk and peril,
   and YOU assume all responsibility for the result.

   Here are the patches:


   ===| The 'AT Patch' |===========================================

   HOW TO PATCH 'CP/M-86 FOR THE IBM PC AND IBM PC XT, VERSION 1.1'
   TO RUN ON ANY AT-CLASS MACHINE (286, 386, 486, Pentium, etc.)
   (Patch developed by Richard Kanarek - November, 1995)


   TO MAKE THE PATCH UNDER DOS:

     1. Using a byte-level editor on the CPM.SYS file, locate the
        byte at absolute file offset 3DAFh.  The byte will be ABh.

     2. Change that byte to 47h.

     3. Now locate the byte at absolute file offset 3DB9h.  The
        byte will, again, be ABh.

     4. Change that byte to 47h.

     5. Save these changes to disk.

     6. Boot your machine from this patched version of CPM.SYS.
        The 'patched' version will also work fine with 8086,
        8088 and V20-based IBM-compatibles.



   ===| The 'Year 2000 Patch' |====================================

   HOW TO PATCH 'CP/M-86 FOR THE IBM PC AND IBM PC XT, VERSION 1.1'
   TO PERMANENTLY FIX THE 21st CENTURY DATE PROBLEM
   (Patch developed by Jake McAllister)


   TO MAKE THE PATCH UNDER DOS:

     1. Using a byte-level editor on the CPM.SYS file, locate
        the ASCII bytes at absolute file offsets 37ABh ('1')
        and 37ACh ('9').

     2. Change the '1' to a '2,' and the '9' to a '0.'  

     3. Save the changes to disk.

     4. Boot your machine from this patched copy of CPM.SYS.
  


   TO MAKE THE PATCH UNDER CP/M-86:

     1. Download and extract the binary file editor FILEVIEW
        (FV.CMD), available from the 'Downloadable Files' page
        of this web site.

     2. Set the CPM.SYS file's attributes to 'READ/WRITE' and
        'DIR.'  ( STAT CPM.SYS $DIR RW )

     3. Invoke FV CPM.SYS

     4. Press 'N' ('Next') repeatedly until you arrive at Record
        Number 0000111d.

     5. Press 'A' to 'Amend' the record.

     6. Press the TAB key to switch the cursor over to the ASCII
        side of the data.

     7. Move the cursor to Offset 43d.  You should see '19' at
        that location.

     8. Type over the existing numbers '19' with the numbers '20',
        and then press the ENTER key.

     9. Press 'Y' in response to the 'Save record?' prompt.

    10. That's it!  The 'patch' has been made.  Press 'Q' to exit
        FILEVIEW.

   After making this 'Year 2000 patch,' you may then use normal,
   non-Y2K-aware clock/calendar-setting software to set the CP/M-86
   system date and time from the computer's hardware clock.  The
   software is available on the 'Downloadable Files' page of this
   web site.