mailing list archives
Re: Did a 16-bit counter overflow shut down Comair?
From: "Mike Nice" <niceman () att net>
Date: Tue, 28 Dec 2004 22:27:45 -0500
Earlier this year, an overflow of a 32-bit counter in Windows shut down
traffic control over southern California for 3 hours:
Microsoft server crash nearly causes 800-plane pile-up
This problem occurred because of a known design flaw in older versions of
Not quite true. Although an old version of Win98 had an overflow, this
overflow was in the application, not the OS.
..."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. "