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History's Worst Software Bugs
bharatm writes "Wired has an article on the 10 worst sofware bugs.. From the article 'Coding errors have sparked explosions, crippled interplanetary probes -- even killed people. Here's our pick for the 10 worst bugs ever, but the judging wasn't easy.'"
I designed and build a diagnostic radiology workstation (in 1997, in Java 1.1, 4x5 megapixel monitors, still in use today). During the development effort we were regaled with stories of software glitches in medical systems resulting in disaster. It really keeps you focused.
In one case, a radiation treatment system had a bug where if you used the backspace key when entering the dose a patient received, the display would show you deleted the last digit, but internally you hadn't. So the patient would recieve 10^backspace times the intended dose of radiation. Not a big deal normally, since the techs would typically shut the machine off between treatments. Until one day when they had two patients needing treatment back to back. The tech knew something was wrong when the machine was running for an unusually long time. The patient knew something was wrong when he died.
On our team a defect that crashed the system was considered severity 2. Severity 1 was reserved for defects that could result in a mis-diagnosis, which most patients agree is worse than a crash.
I actually did a research report on the Therac-25 incident while I was in Software Engineering class a few semesters ago (I was also in Technical Writing at the time, so I could kill two assignments with one report!) ;-) The details of the incident(s) are actually quite fascinating and sometimes spine-chilling.
Here's the report in PDF if anyone's interested: reportfinal.pdf
And in HTML for those of you who prefer it: link
From Wiki page:
It also found that FirstEnergy did not take remedial action or warn other control centers until it was too late because of a bug in the Unix-based General Electric Energy's XA/21 system that prevented alarms from showing on their control system, and they had inadequate staff to detect and correct the software bug. The cascading effect that resulted ultimately forced the shutdown of more than 100 power plants.
In the words of the old chestnut, "If you're calm and confident when everyone around you is running around in blind panic, you clearly don't understand the situation."
Welcome to the Panopticon. Used to be a prison, now it's your home.