Subject: Re: y2000 for the gs
From: casa@unm.edu (Jim Pittman)
Date: Wed, Jan 20, 1999 9Ç0(H
Message-id: <78523g$bt6@enzu.unm.edu>

Re:

> Subject: y2000 for the gs      Date: 17 Jan 1999 16:29:56 GMT
> From: psmoller@aol.com (PSmoller) Newsgroups: comp.sys.apple2
> 
> Does anyone know of a chip replacement that will allow the 2gs to go
> to the year 2000 and beyond. If not is there a software patch that
> will do the same thing. Is there a patch for Managing your Money?
> Your can email me at psmoller@aol. com. My computer club would really
> appreciate the help.

The Apple IIgs clock should be fine with y2k dates up through the
year 2039 or so. The problem is not with the clock, it's with what
programs do with dates. Programs can read the computer's clock to get
the date, or they can ask the user to type in a date. Are there any
Apple IIgs programs that ask you to type the date that allow four
places for the year? I don't know. If I boot up Copy II Plus 8.2 or
9.1 or AppleWorks versions 2, 3, 4 or 5 on my Apple IIc Plus, they
all ask me to type in the date but they only let me type two digits
for the year. (If I run these on a IIgs, I assume they read the
year (as two digits only?) from the computer's clock.)

If a program only provides two places for the year, then you can type
in "99" today and you can type in "00" next January. The value "00"
can be interpreted at least three ways:

1) The year zero ("00" is just read as "00" or zero)
2) The year 1900 (the program prepends a "19" to the "00")
3) The year 2000 (the program prepends a "20" to the "00")

In case (1) it's up to the human to know what year (century) it is.

In case (2) for contemporary dates you will have problems in eleven
months when 1999 rolls over to 2000. (But if your data contain dates
from the 19th century -- the 1800's -- or the 21st century -- the
2000's -- you already have problems.)

If your program exhibits case (3) behavior, you are all set for the
early 2000's -- unless your data include real dates in both the early
20th and the early 21st centuries. Example: my Dad was born in June
1911. He tells me he's going to live to be a hundred. Okay, if I have
a program that only lets me enter two digits for the year, and if it
treats a year entry of "11" as "1911" then his birthdate is entered
correctly. But if he dies in July 2011 and I type in the date he
died, the program will report that he lived one month instead of 100
years and 1 month! (What do you suppose this program would report if
he were to die in May of 2011?)

Here's a little exercise: use a utility to change the modification
date of a test file. (I used Vitesse's DELIVERANCE.) Set the year to
"00" and then get into the finder and see what it reports for the
file date. It will say the year is "2000". Now change the year to
"01" then "02" then "03" and so on and see what the finder reports.
You'll find that the finder will give you "2031" if you put in "31"
for the year, but will give you "1941" if you put in "41". (You can
try various years and months to find the transition point.)

A few useful Apple II programs that fall into case (2) can be patched
to behave as case (3) -- I believe AppleWorks 5.1 is the prototypical
example. A few will remain case (1) and it's up to you to know what
century it is. Unfortunately there may be several case (2) programs
that won't be fixable. If you use such a program, look for something
else to move your data into before 2000.

Another kind of y2k problem is, will a program know, despite the year
2000 being evenly divisible by 400, IT IS A LEAP YEAR, so that the
day after 28 February 2000 is 29 February 2000 and not 1 March 2000?

My ][ cents.

- Jim Pittman - AppleQuerque Computer Club - where there are still a
few Apple II enthusiasts among the Mac people - casa @ unm . edu