Re: Y2k problems on a IIgs w/ProDOS 4.0.2

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

Tail Kinker <tailkinker@home.com> wrote:

> On Sat, 02 Oct 1999 18:44:15 -0400, bvito <bvito@ne.mediaone.net> had
> the gall to suggest:
> 
> >will there be any year 2000 problems with a IIgs running ProDOS 4.0.2?
> >thanks.
> 
> Yes - the internal clock can't handle the Year 2000 rollover - at
> least not on my ROM 01 IIGS.  So I just set the date to ten years
> ago... :)

News to me.  There have never been reports of Y2K problems with the IIgs
internal clock.  I just tested it on my ROM 3, and it rolled over
perfectly happily.

(I don't have a live ROM 1 system handy to check it - has anyone else
done a similar test?)

The IIgs clock is implemented the same way as the Mac: the clock chip
uses a four byte register which increments every second (the base year
is probably 1904, as with the early Mac models).  The firmware converts
this into a text string or record-based time, and it was specifically
designed to use values in the range 0-39 for 2000-2039.

There is even a technote (ProDOS #28) which defines how a year of 2000
or later will be represented, and it states that the chosen method
(40-99 are 19xx, 0-39 are 20xx) "allows the same range of years that the
Apple IIgs Control Panel CDA currently does".

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