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Communicator 3000 MPE/iX Release 6.0 (Platform Software Release C.60.00): HP 3000 MPE/iX Computer Systems > Chapter 9 Year 2000 Enhancements Year 2000 Enhancements for MPE/iX |
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by M Gopalakrishnan This version of MPE/iX provides enhancements to the operating system for the year 2000 and beyond. The enhancements include the enhancements to the operating system commands, utilities, VPLUS and databases. This article explains the enhancements. The year 2000 issues stem from the ability to handle correctly the year 2000 and beyond. This is particularly an issue for systems and applications that are using a two-digit year to express dates. There are a few commands, utilities, and databases in MPE/iX which were designed to handle two-digit years and these had to be enhanced to support year 2000 and beyond. The year 2000 is a leap year, and this also had to be addressed. The MPE/iX operating system uses the Gregorian calendar and its definition of leap year: any year that is exactly divisible by 400, or that is exactly divisible by 4 and not exactly divisible by 100. One of the ways for handling two-digit year input is to interpret the years in the method called fixed window method. In this method, the two-digit years map as follows:
For example, both of the following STREAM commands will schedule the JOBFILE as January 21, 2001:
The CALENDAR intrinsic and CALENDAR date representation format are widely used in MPE/iX. There are many other intrinsics that accept or return dates in calendar format. The following discussion clarifies the interpretation of calendar format year value. The CALENDAR intrinsic returns the CALENDAR date, including the day of year and the year of century. The existing CALENDAR intrinsic documentation refers to the year as "year of century." This should be interpreted as "year since 1900." The new definition of the CALENDAR intrinsic is as follows: Syntax
where date is a 16-bit unsigned integer (assigned functional return). This returns the CALENDAR date in the following format:
Description For the year 2000, the CALENDAR intrinsic will return the year as 100, for 2001 as 101, and so on. With this current interpretation, CALENDAR format can handle years through 2027. All intrinsics accepting or returning dates in CALENDAR format will behave the same way as the CALENDAR intrinsic.
HPFOPEN item 31 (labeled tape expiration parameter) and FOPEN (formmsg label tape parameter) will accept both two- and four-digit years as the labeled tape expiration date. This is the same as the FILE command expiration date parameter. For an interpretation of two-digit years, refer to the section, "Two-Digit Years Interpretation," in this article. The following commands are enhanced to support both two- and four-digit years. For an interpretation of two-digit years, refer to the section, "Two-Digit Years Interpretation." New syntax for the commands with parameters accepting years follows:
The available HPYEAR variable is corrected to return the last two digits of the current system year, and a new CI variable is added to have the four-digit current system year. Existing variable: Title not available (CI Variables )
New four-digit year variable: Title not available (CI Variables )
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