Re: Y2K and P8 TN #28 (Re: No-Slot Clock)

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

phoenyx <quazar@dcnet2000.com> wrote:

> Oops, I just checked my GS & P8 reference. The problem
> is in the clock driver code. This is in the aux $d0 bank on
> a language card or equivalent.

Yes, but this driver changes according to the machine (IIgs or other)
and can be replaced by a third-party driver if you don't have a
Thunderclock (or clone).

The clock driver is buried inside the kernel, but I would regard it as a
separate piece of software.  None of the rest of the ProDOS kernel knows
anything about the date and time, except for the purposes of copying
them from the data provided by the clock driver, and calling the clock
driver at the appropriate point.

In fact, the Thunderclock driver doesn't know anything about the year
notation either.  It just blindly looks up a table inside the driver,
which has to contain an appropriate value for the year (derived from the
month, day of month and day of week).  This table is patched by the
CLOCK.PATCH program which Apple supplied.  You need the newer version of
this utility to get compliant year encoding.

The IIgs clock driver used by ProDOS _does_ know about the year
encoding, because it gets the year from the IIgs toolbox, and has to
convert it to the form expected by ProDOS.  The IIgs clock driver in
ProDOS-8 1.9 and earlier uses the old unofficial convention (2000 is
encoded as 100) while ProDOS-8 2.0.1's IIgs clock driver changes it to
comply with TN.PDOS.028.

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