AppleWorks 5.1 and Bredon ProDOS Y2K Patch

["Hugh Hood" <hughhood@earthlink.net>]

RE: Using AppleWorks 5.1 with Professor Bredon's ProDOS patch
--------------------------------------------------------------

THANKS.
-------

First, I offer a big 'thank you' to Professor Bredon for taking the time and
making the effort to re-examine the date routines in ProDOS 2.0.3 and for
coming up with a patch that will allow proper relative dating across the
1999-2000 boundary, at least through 2027. Others may differ, but I prefer
his approach to that given by Apple in its ProDOS technote.


BACKGROUND.
-----------

After I wholeheartedly adopted the 'Bredon Method', I was concerned when
AppleWorks 5.1 provided me with incorrect results when using the Ultramacros
'date' command (OA-'), the 'PD' command in the AWP printer options, and when
using the '@' command to enter the date when either printing ADB reports,
ASP documents, or when entering the date in an ADB date field.

So, some investigation into AppleWorks 5.1 revealed that Randy Brandt, a
fine programmer himself, had accounted for Apple's 'approved' method for
handling the Y2K date change and built the necessary routine into AppleWorks
5.1. In a nutshell, based on Apple's approved method of rolling year 100
(2000) back to 0, he provided a routine whereby dates greater than year 60
would have '19' as the century prefix, and dates less than year 60 would
have '20' as the century prefix. (I forgot how year 60 is handled. <g>)


THE PATCH.
----------

To allow AppleWorks 5.1 to report the correct year prefix when using ProDOS
2.0.3 modified by the 'Bredon Method', a simple two-byte patch is required.
(Actually a one-byte patch would do it, but the two-byte patch is less of a
hack, and works if you set your clock back into the 1900's.)

For those who prefer to patch in memory rather than on disk, the AppleWorks
5.1 memory locations affected are as follows:


ADDRESS:       FROM:        TO:    COMMENT
-------------------------------------------------------
$AE5F          $3C          $64     1960 to 2000

$AE60          $B0          $90     Switch GT/LT Opcode


For those who prefer to patch on disk rather than in memory, the AppleWorks
5.1 file 'APLWORKS.SYSTEM' locations are as follows:

NOTE: Follow File = APLWORKS.SYSTEM
      Relative Block = 23

ADDRESS:       FROM:        TO:    COMMENT
-------------------------------------------------------
$0D3          $3C          $64     1960 to 2000

$0D4          $B0          $90     Switch GT/LT Opcode


Of course, you _can_ use any block editor, but considering who came up with
the 'Bredon Method' patch, anyone with any shred of decency will use
ProSel's 'Block Warden'. <g>


FINAL NOTE:
-----------

There are some patches out that modify AppleWorks 5.1 to work with the NON
'Bredon Method'. You will not want to apply these patches, unless you prefer
the Apple approved method. Again, the major advantage to the Bredon method
is that it provides proper relative dating. (e.g. files dated 1999 are
_older_ than files dated 2000 and vice versa).

As the Deja ][ boys (Messrs. Brandt and Munz) put it, 'AppleWorks forever'.

P.S. - Handling years _after_ 2027 is left as an exercise for the reader.

Hugh Hood