5 ms·

Remember the story about running a navy ship on Windows NT? Fool me twice... I don't blame them for sticking with the DEC stuff :-)

tzs 12y ago
Old DEC computers would have done exactly the same thing NT did on that ship, which is also exactly the same thing current Windows, Linux, and OS X systems do. The problem they had was that someone entered a zero in a form field that was not allowed to be zero. The application that received this zero used it as the denominator in a divide, and so incurred a divide by zero exception. That application did not have a divide by zero handler, and so NT did the same thing pretty much every operating system does in that case, and it killed the application. That application happened to be vital for engine operation, and so the ship was dead in the water and had to be towed to port. It might seem shocking that they did not enforce important rules like "this field cannot be zero" on the data entry form, or that they did not handle divide by zero exceptions in a mission critical application (or at least have a procedure for restarting the application if it died), but this ship was a testbed for experimental software so maybe those things get added later, once they have determined that the new system works well enough to continue developing? At least, I hope it was something like that, and not something like the subcontractor who did the data entry terminals thought the application would do the data validation, and the subcontractor who did the application thought the terminals would do it.
- tedunangst 12y ago
  But see, if they'd been using Linux, they would have had the kernel source and they could have patched the SIGFPE handler to do a virtual longjmp back to the part of the program that did form entry.
  - yuhong 12y ago
    You don't need the kernel source to do that.
    - tedunangst 12y ago
      Sure, one could patch the application too, but that can also be done on NT.
- cbd1984 12y ago
  I didn't think Linux was vulnerable to the 45-day forced-reboot bug.
  - tedunangst 12y ago
    Are you talking about the Windows 95/98 49 day time rollover bug? That didn't affect NT either.
    - cbd1984 12y ago
      > Are you talking about the Windows 95/98 49 day time rollover bug? Yes. > That didn't affect NT either. Oh. OK.
    - RVuRnvbM2e 12y ago
      True, now you have a full 497 days. https://support2.microsoft.com/kb/2553549 https://support2.microsoft.com/kb/2553549
      - tedunangst 12y ago
        Still better than 208.5 days. :) https://access.redhat.com/solutions/68466 https://access.redhat.com/solutions/68466
        cbd1984 12y ago
        Fixed: https://www.kernel.org/pub/linux/kernel/v2.6/longterm/ChangeLog-2.6.32.50 https://www.kernel.org/pub/linux/kernel/v2.6/longterm/Change... (I mean, in case anyone else was curious like I was.) Kernel developer thread: http://thread.gmane.org/gmane.linux.kernel/1132515 http://thread.gmane.org/gmane.linux.kernel/1132515
- Roboprog 12y ago
  Now let's consider the culture involved in writing software for the respective systems. Do you want the typical point n click weenie writing the software to control your military hardware?

tzs 12y ago

Old DEC computers would have done exactly the same thing NT did on that ship, which is also exactly the same thing current Windows, Linux, and OS X systems do. The problem they had was that someone entered a zero in a form field that was not allowed to be zero. The application that received this zero used it as the denominator in a divide, and so incurred a divide by zero exception. That application did not have a divide by zero handler, and so NT did the same thing pretty much every operating system does in that case, and it killed the application. That application happened to be vital for engine operation, and so the ship was dead in the water and had to be towed to port. It might seem shocking that they did not enforce important rules like "this field cannot be zero" on the data entry form, or that they did not handle divide by zero exceptions in a mission critical application (or at least have a procedure for restarting the application if it died), but this ship was a testbed for experimental software so maybe those things get added later, once they have determined that the new system works well enough to continue developing? At least, I hope it was something like that, and not something like the subcontractor who did the data entry terminals thought the application would do the data validation, and the subcontractor who did the application thought the terminals would do it.

tedunangst 12y ago
But see, if they'd been using Linux, they would have had the kernel source and they could have patched the SIGFPE handler to do a virtual longjmp back to the part of the program that did form entry.
- yuhong 12y ago
  You don't need the kernel source to do that.
  - tedunangst 12y ago
    Sure, one could patch the application too, but that can also be done on NT.
cbd1984 12y ago
I didn't think Linux was vulnerable to the 45-day forced-reboot bug.
- tedunangst 12y ago
  Are you talking about the Windows 95/98 49 day time rollover bug? That didn't affect NT either.
  - cbd1984 12y ago
    > Are you talking about the Windows 95/98 49 day time rollover bug? Yes. > That didn't affect NT either. Oh. OK.
  - RVuRnvbM2e 12y ago
    True, now you have a full 497 days. https://support2.microsoft.com/kb/2553549 https://support2.microsoft.com/kb/2553549
    - tedunangst 12y ago
      Still better than 208.5 days. :) https://access.redhat.com/solutions/68466 https://access.redhat.com/solutions/68466
      - cbd1984 12y ago
        Fixed: https://www.kernel.org/pub/linux/kernel/v2.6/longterm/ChangeLog-2.6.32.50 https://www.kernel.org/pub/linux/kernel/v2.6/longterm/Change... (I mean, in case anyone else was curious like I was.) Kernel developer thread: http://thread.gmane.org/gmane.linux.kernel/1132515 http://thread.gmane.org/gmane.linux.kernel/1132515
Roboprog 12y ago
Now let's consider the culture involved in writing software for the respective systems. Do you want the typical point n click weenie writing the software to control your military hardware?