The overall video series looks pretty interesting too, although it's more about computers in general than embedded computers specifically. (Scroll down past the video link to see a list of how time-keeping bugs have caused severe outages and even deaths.)
"Summary: Published on Dec 30, 2013 A web app that works out how many seconds ago something happened. How hard can coding that be? Tom Scott explains how time twists and turns like a twisty-turny thing. It's not to be trifled with! (Embedded from YouTube; <computerphile>)"
Bonus content: here is a rogue's gallery of time goofs that I happen to include in my classroom lectures. If you know of other high profile outages or worse please submit as comments and I'll update the list as we go. (Note: this is only bugs caused by bad time-keeping, not all software outages):
- Feb. 1991: Patriot missile failure due to floating point time roundoff; 28 deaths (link)
- Dec 31, 1999: Y2K
- Feb. 2007: F-22 raptor computer system crash due to crossing the international date line (link)
- Feb. 2008: Microsoft Zunes basically bricked by leap year bug (link)
- Mar. 2011: iPhones spring back instead of springing forward (link)
- Mar. 2012: Windows Azure leap-year bug takes down G-cloud (link)
- Jul. 1, 2012: Leap second bug wreaks havoc upon on-line services using NTP (link)
- Sep. 2013: Deep Impact comet mission ends due to calendar date rollover fault (link)
- May 2015: Boeing 787 timer rollover bug crashes engine software after 248 days (link)
- Jul. 1, 2015: Another leap second problem, but not nearly as bad as 2012 (link)
- Feb. 2016: iPhone prank bricks iPhones if date set back to zero Unix time (link)
- Feb. 2016: Leap year bug leaves passengers without bags at Dusseldorf airport (link)
- Jan. 19, 2038 03:15:07 GMT: Unix time rolls over ("Y2K for Unix")
(There are relatively few listings before 2010. Don't think for a minute that time suddenly got harder. What got worse was probably more things can be broken and result in headlines due to timekeeping faults.)
Update 11/8/2016: This is an entertaining and enlightening post about the quirks of time: Falsehoods programmers believe about time and it has a follow-up of additional falsehoods
Update 11/8/2016: This is an entertaining and enlightening post about the quirks of time: Falsehoods programmers believe about time and it has a follow-up of additional falsehoods
No comments:
Post a Comment
Please send me your comments. I read all of them, and I appreciate them. To control spam I manually approve comments before they show up. It might take a while to respond. I appreciate generic "I like this post" comments, but I don't publish non-substantive comments like that.
If you prefer, or want a personal response, you can send e-mail to comments@koopman.us.
If you want a personal response please make sure to include your e-mail reply address. Thanks!