Re: Did a 16-bit counter overflow shut down Comair?

["Mike Nice" <niceman () att net>]

> Earlier this year, an overflow of a 32-bit counter in Windows shut down
air
> traffic control over southern California for 3 hours:
>
>  Microsoft server crash nearly causes 800-plane pile-up
> http://www.techworld.com/opsys/news/index.cfm?NewsID=2275
>
> This problem occurred because of a known design flaw in older versions of
> Windows:
>
>   http://tinyurl.com/5n9gc


  Not quite true.   Although an old version of Win98 had an overflow, this
overflow was in the application, not the OS.

  http://www.spectrum.ieee.org/WEBONLY/resource/nov04/1104nair.html

 ..."But it's a software glitch that makes the reboot procedure necessary in
the first place, says Riggs. And that glitch resides in an auxiliary
system-the VSCS Control Subsystem Upgrade (VCSU)."

 "Inside the control system unit is a countdown timer that ticks off time in
milliseconds. The VCSU uses the timer as a pulse to send out periodic
queries to the VSCS. "