Re: Railways and the Millennium Bug
Paul Mansell (pmansell@bigpond.com)
30 Apr 98 08:50:05 GMT
Ashley Wright <ajwright@ozemail.com.au> wrote in article
<3546d3c4.1029637@news.ozemail.com.au>...
> Where the Y2K problem comes in is in databases, especialy those used
> in the financial system. No doubt you are aware that in the early ages
> of computers the machines only gave the date as a two digit code and
> the programs to save memory only saved the last two digits of the
> date. This could cause problems in interest calculations because
> comparisons need to be made between two dates with different century
> dates. For the railway and indeed the travel industry in general this
> is where the problems could be in their ticketing and checkin systems.
> Airlines in particular use programs that date back to the 60's and are
> very hard to change. A problem for eg may be caused where I person
> books to fly somwhere on say 31st Dec 1999 and return on 2-1-2000. The
> system may well throw a wobbly because technicaly the return date is
> before the departure date.
>
> Anyway my two bobs worth!
> --------------------------------------------------------
> Ashley Wright, Sydney, soon to be Canberra, Australia
> ajwright@ozemail.com.au
> www: http://www.ozemail.com.au/~ajwright
> ---------------------------------------------------------
>
I know it's not railways but I was a programmer once!
Many systems use something called the 'Juian date' which takes a ceratin
date (e.g. 1/1/1980) and makes this the reference point, i.e. day 1. Every
date since this date, simply is expressed as a number equal to the number
of days elapsed from the reference point, i.e. 2/1/1980 would be 32,
1/1/1981 would be 367, 1/1/82 would be 732, etc. etc. Excel and other
spreadsheet programs can work like this, functions like DATEVALUE can
convert numbers into dates (I think Excel 97 starts at 1901!). This system
is used because it makes working out days between dates very easy indeed.
Therefore on the fateful day, the system would just add 1 onto the date
number and this can be converted to the normal date we know about. How it
appears is another story.
There is a lot of hype about big problems happening and business centres
shutting down, etc. I don't think so, Tim! Sure, the SRA will fix it, their
fare collection is fully computerised and they won't want to lose a cent!
My 2c only