4 ms·
There's a certain exchange out there that I wrote some code for recently, that runs on top of VAX, or rather OpenVMS, and that has an epoch of November 17, 1858
by DrBazza 2y ago
There's a certain exchange out there that I wrote some code for recently, that runs on top of VAX, or rather OpenVMS, and that has an epoch of November 17, 1858, the first time I've seen a mention of a non-unix epoch in my career. Fortunately, it is abstracted to be the unix epoch in the code I was using.
- pavlov 2y agoApparently the 1858 epoch comes from an astronomy standard calendar called the Julian Day, where day zero was in 4713 BC: https://www.slac.stanford.edu/~rkj/crazytime.txt https://www.slac.stanford.edu/~rkj/crazytime.txt To make these dates fit in computer memory in the 1950s, they offset the calendar by 2.4 million days, placing day zero on November 17, 1858.
- deleted 2y ago[deleted]
- hanche 2y agoIt’s called the modified Julian day (MJD). And the offset is 2,400,000.5 days. In the Julian day way of counting, each day ended at noon, so that all astronomical observations done in one night would be the same Julian day, at least in Europe. MJD moved the epoch back to midnight. https://en.wikipedia.org/wiki/Julian_day https://en.wikipedia.org/wiki/Julian_day
- spiffytech 2y agoThere's an old Microsoft tale related to the conflict between Excel's epoch of Jan 1 1900 vs Basic's Dec 31 1899: https://www.joelonsoftware.com/2006/06/16/my-first-billg-review/ https://www.joelonsoftware.com/2006/06/16/my-first-billg-rev...
- evmar 2y agoAnother common computing system to be aware of: the Windows epoch is 1-Jan-1601.
- NoInkling 2y agoPostgreSQL internally uses a 2000-01-01 epoch for storing timestamps.
- kalleboo 2y agoThe classic MacOS, Apple's HFS file system (also used in OS X), and PalmOS all had en epoch of January 1, 1904. The macOS/Swift Foundation API NSDate.timeIntervalSinceReferenceDate uses an epoch of January 1, 2001. edit: Looks like Wikipedia has a handy list https://en.wikipedia.org/wiki/Epoch_(computing)#Notable_epoch_dates_in_computing https://en.wikipedia.org/wiki/Epoch_(computing)#Notable_epoc...