[Info-vax] 2010 date issues

[Paul Sture]

In article 
<f186aed5-b3e6-47d0-9b27-f8a2bda7d941 at k19g2000yqc.googlegroups.com>,
 Hein RMS van den Heuvel <heinvandenheuvel at gmail.com> wrote:

> On Jan 15, 2:10 pm, Paul Sture <paul.nos... at sture.ch> wrote:
> > In article <xr14n.227$I8.... at news.indigo.ie>,
> >  Tom Wade <nos... at picard.eurokom.ie> wrote:
> :
> > > Another typical 'short-cut' was where systems have a two digit field in a
> > > database record for the date.  The Y2K fix involves translating between
> > > the 2-digit stored date, and a 4-digit display date.
> > >   To do this, some cutoff is assumed, for example if the 2-digit date is 
> > > < 50
> > >   it is assumed 2000
> 
> :
> 
> > This exists in OpenVMS Alpha (I don't know about IA64), and has to be
> > one of the most misguided attempts ever to address the Y2K issue.
> 
> Correct. It is coded up in the core SYS$ASCTIM.
> Undocumented with that routine.
> 
> 0 - 99 use a 2-digit year handler in there.
> 100 - 1600, and 10000+ are invalid
> 1601 - 9999 normal.
> 
> It can be seen with simple DCL like:
> 
> $ write sys$output f$cvtime("--56") --> 2056-01-16 00:00:00.00
> $ write sys$output f$cvtime("--57") --> 1957-01-16 00:00:00.00
> 
> Or in any program like:
> 
> 1       map (x) long bintim, long bintim_hi, string asctim=23
>         while 1+1=2
>           INPUT asctim
>           CALL SYS$BINTIM (asctim,bintim)
>           CALL SYS$ASCTIM (0% by value,asctim, bintim, 0% by value)
>           PRINT asctim
>         NEXT
> 
> The transition year is hardcoded in an executive cell:
> 
> $ anal/sys ...
> SDA> eval @EXE$GL_TRANSITION_YEAR
> Hex = 00000000.00000039   Decimal = 57
> 
> Anything above that (thru 99)  becomes 1900 + YY, below is 2000 + YY
> You can poke that cell to change the transition, but the code does NOT
> test a special value to make a year less than 100 invalid. That would
> have been thoughtful.
> Base code was added in 1991, changed to use the cell in 1992.
> 
> fwiw,
> Hein.

Thanks for the detail. I didn't realise it went so far back. Is that the 
right time frame for it being part of the Alpha port?

-- 
Paul Sture