Re: Weird IIgs Rom 01 bug

[Benjamin Ketcham <bketcham@drizzle.com>]

Jayson Smith <nospamratguyspambegone@nospamplease.bellsouth.ihatespam.net> wrote:
> Hi,
> I've been playing around with a program I have which lets blind people
> adjust control panel settings without having to go into the desk accessory.
> I was fiddling around with the clock section, doing some peeking, poking and
> setting of the clock and found some very weird behavior so I wrote a clock
> print/set program to discover exactly what happens.
> It seems that at least on the Rom 01 GS, at exactly 06:28:16 on 02/06/2040
> the time becomes 00:00:00 on 01/01/1904.  This happens no matter if you set
> the clock to a date/time past that mark or if you set it a few seconds
> before and let it pass that time naturally.  Quite literally, one second
> it's 06:28:15 on 02/06/2040 and the next second it's 00:00:00 on 01/01/1904.
> I think this might happen once or twice more between then and the year 2155,
> the highest year the clock format could handle.  Setting the date to
> 12/31/2155 and the time to 23:59:59 yielded 23:59:59 on 07/27/1976 or
> something like that.
> Now I seriously doubt that there will be many IIgs's still functional in the
> year 2040 but I just wanted to let people know about this weirdness and see
> if anybody has any thoughts about what might be causing it.
> This is untested on a Rom 00 or 03 as I don't have those machines.  If
> anybody wants, I can send the Prodos Basic program I've been using for my
> experimentations.
> Jayson.

Perhaps this is due to rollover of the integer type used for clock timing
on this machine; similar to 32-bit Unix, which will have a problem in
something like 2027.  Unix counts the seconds since Jan 1 1970; when
that is stored as a 32-bit integer (uh, signed IIRC), that's how many
you get.  Of course 64-bit data types push the rollover time well out
there...  I'm sure almost 60 years seemed like overkill at the time, but
the fact is that old machines continue to be used, and it is damn
inconvenient for them to have a built-in failure mechanism.
I bet there will be *some* Apple IIs of every flavour still running --
even in 500 years (perhaps with relatively few original parts by then).
(Why can't these OSes at least support a "shiftable Epoch"??)

--Benjamin