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Another “funny” detail: >The maximum representable date is February 6, 2040 at 06:28:15 GMT. http://dubeiko.com/development/FileSystems/HFSPLUS/tn1150.html ht

• stygiansonic 12y ago
  Interesting: I didn't realize the "Epoch" in this case was "midnight, January 1, 1904, GMT". Given that the representation is stored as an unsigned 32-bit integer, it seems like you cannot represent dates older than this "Epoch" starting value. Since it's a file system, that's probably of much less concern than a more general date-time format. However, does anyone know the genesis behind which this particular date was chosen? It's far enough back to not cause any issues and appears to be close to the minimum date-time value obtained using the minimum value for signed 32-bit integer and the standard Unix Epoch (which would be around 13 Dec 1901), but other than that?
  • pjc50 12y ago
    https://support.microsoft.com/kb/180162?wa=wsignin1.0 https://support.microsoft.com/kb/180162?wa=wsignin1.0 The 1900 epoch needs additional code to handle the fact that 1900 was not a leap year. Why not the UNIX epoch? Well that's another question entirely.
    • Someone 12y ago
      Also: http://support.microsoft.com/kb/214326 http://support.microsoft.com/kb/214326: "Explains why the year 1900 is treated as a leap year in Excel 2000" Mac OS was written in a time of memory scarcity; 1904 is just an easier choice for the epoch than 1900. That's also why they didn't choose the Unix epoch, as it would have required supporting multiple epochs, one for disk time stamps, and one to handle birth dates (time stamps on classic Mac OS are unsigned; there were no times before the epoch. And yes, there were no Mac users over 80 :-))