ASP LaserTraq, Руководство пользователя

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LaserTraq 25
Year 2000 Statement
The ASP LaserTraq contains a clock/calendar component that does not
maintain century information – that is, the year is stored as two digits
only. The application program loaded into the LaserTraq has the
responsibility of determining the century and converting the year from
two digits to four digits.
There are two main ways of converting a two digit year to a four digit
year, and these are the “assumed century” and the “pivot” method.
In the assumed century method, a fixed century prefix is added to the two
digit year – for example, 20 is prefixed to the year so that all dates from
the year 2000 to 2099 are possible. If this method is used, it would not
be possible to use for the clock/calendar to be set to dates before the year
2000 or after the year 2099.
In the pivot method, a pivot year is picked, and all two digit numbers less
than or equal to the pivot year would be assumed to begin with 20 and all
years greater than the pivot year would be assumed to begin with 19. If,
for example, a pivot year of 90 was used, the clock/calendar could be set
to dates between 1990 and 2089. Similarly, if a pivot year of 20 was
used, the clock/calendar could be set to dates between 1920 and 2019.
The decision to use the assumed year method or the pivot method of year
expansion will be decided based on the requirements of the application
program.
Note that in either case, the 100 year range of the two digit year
clock/calendar only compromises the dates to which the calendar may be
set – it does not compromise any calculations that the application
program might perform on dates. Provided the necessary range of any
such date calculations are correctly and completely specified before the
application program is written, correct operation and therefore year 2000
compliance can be assured.
Most programs do not need to perform calculations on dates, and in these
cases, full and valid year 2000 compliant operation of the clock/calendar
is claimed for use between the years 2000 and 2099 if the assumed
century model of year expansion is used, or between the years
determined by the pivot year if the pivot year method of year expansion
is used.