[email protected] (Joel C. Ewing) writes: > ISPF directory dates are stored in the highly-peculiar IBM Julian Date > format variant used for SMF timestamps: a positive-signed PL4 field > currently defined as 0cyydddF. Although the formal definition at this > point only allows for "0c" being "00" for 19xx years and "01" for > 20xx, this format could represent any year from 1900 through 11899 by > the obvious extension of the date format to "ccyydddF" where cc is the > top two decimal digits of a four-digit representation of "year-1900", > so it may be considered roughly equivalent to using a four-digit > representation of the year. All code changes we made for Y2K to > account for the "01yy" date enhancement assumes this obvious extension > for 21xx and beyond. One can make a valid argument that this is a > horrid date format to keep for another 98 centuries, but not on the > grounds that it can't be made to work. The current definition was an > unfortunate consequence of choosing to reduce Y2K remediation work by > minimizing date comparison problems at Y2K with pre-2000 dates saved > in the older "00yydddF" Julian Date format.
misc. past posts mentioning early '80s internal online discussion on the approaching y2k problem and some examples of date issues: http://www.garlic.com/~lynn/99.html#24 BA Solves Y2K (Was: Re: Chinese Solve Y2K) http://www.garlic.com/~lynn/99.html#233 Computer of the century http://www.garlic.com/~lynn/2000.html#0 2000 = millennium? http://www.garlic.com/~lynn/2000.html#94 Those who do not learn from history... above includes mention of shuttle mission computer date issues. total aside ... last (discovery) shuttle mission keeps getting postponed http://www.pcmag.com/article2/0,2817,2375445,00.asp recent (long-winded) posts mentioning being at discovery's 1st launch: http://www.garlic.com/~lynn/2010i.html#69 Favourite computer history books? http://www.garlic.com/~lynn/2010o.html#51 The Credit Card Criminals Are Getting Crafty -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
