Re: ProDOS year ranges (was: No-Slot Clock)

[dempson@actrix.gen.nz (David Empson)]

laine_h <laine_h@email.msn.com> wrote:

> if I set my thunder clock M0-01 (jan) DAY-06 (sat)  DATE-01 (the first)
> xxx=time
> Prodos (VERS 2.0.1) pokes $bf91 with $C8. That is logical. What should a
> program assume from this info?

The Thunderclock doesn't provide the year to the computer, so the driver
has to calculate it from the month, day of month and day of week.  The
driver contains a table with seven entries (one for each day of the
week), which holds between five and six years (depending on how leap
years fall).

I dug around my documentation, and found information in the release
notes for System 6.0.1 which say that ProDOS-8 2.0.3's Thunderclock
driver has a year range of 1993 to 1998.  The CLOCK.PATCH utility
supplied with Apple II System Disk 4.3 (which includes ProDOS-8 2.0.1)
would have been needed already to patch ProDOS 2.0.x to include 2000 in
its year table.

It seems that this utility has a bug, and was storing the incorrect
values in the year table.

There is a newer version of the CLOCK.PATCH utility which is included
with IIgs System 6.0.1 (on the SystemTools2 disk).  This version is
updated to work with ProDOS-8 2.0.3 (as well as all versions back to
2.0), and it sets up the driver to return 0 instead of 100 for the year
in 2000 (with a corresponding change in subsequent years).

One other note I've picked up: ProDOS-8 2.0.1 modified the IIgs clock
driver to comply with the new definition for Y2K (0 instead of 100), so
P8 versions 1.9 and earlier will be producing the wrong value.

I see also that System 6.0 was the first GS/OS version to use the new
definition, so anyone still running ProDOS-16, or any version of System
4.0 or 5.0.x, is going to run into the same issue.

> Given this and your understanding of the tech note what do you suggest?

Get hold of the current version of CLOCK.PATCH, and use it to update
your copy of ProDOS.  This should fix the driver to comply with the
technote (and GS/OS).

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P O Box 27-103, Wellington, New Zealand