The 5 Worst Software Flops of All Time

by Tori Johnson on June 6, 2011

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The 5 worst software flops of all time

We love to complain about software. It’s second only to the weather on most office hit-lists. And while there are lots of examples of present software glitches and headaches, we thought instead of slamming specific companies, it would be more interesting to take a look at a half-dozen more historical software flubs, flops, and failures that truly changed history:

1962: A funny thing happened on the way to Venus…
This is an example of one of the earliest bits of computer code, which – unfortunately for the Mariner 1 space probe it was written for – is not transferred accurately from paper-and-pencil. This causes Mariner 1’s onboard computer to miscalculate the probe’s trajectory away from Earth, causing it to veer off-course and forcing NASA to destroy it over the Atlantic Ocean.

1988-1996: Kerberos’ not-so-random-number generator
When writing the code for this security system, authors neglect to properly “seed” the program’s random number generator with an actually random seed. For eight years then, as a result, it becomes possible to break into any computer that relies on this system for security authentication.

1990: Please hang up and try your call again…
A bug in the sparkly-new release of software that controls AT&T’s #4ESS long distance switches causes computers to crash when they get a specific message from one of their next-door machines. (Ironically, the message is a report sent out when one of the computers legitimately crashes.) After 60,000 people are left without long-distance service for most of the work-day, software engineers stomp over the sparkly new code with the previous release.

1995/1996: The Blue Ping of Death
A lack of “sanity checks” and “error handling” in code makes it possible to crash all sorts of systems by sending an abnormal “ping” packet to Windows-based computers, which then lock up and display the ever-loved “blue screen of death”.

1996: Mon Dieu!
Working code for France’s Ariane 4 rocket is reused in the Ariane 5. That may have normally been fine and good, were it not that Ariane 5’s faster engines then trigger a flight computer math bug that converts “a 64-bit floating-point number to a 16-bit signed integer.” The faster engines cause the 64-bit numbers to be larger in the Ariane 5 than in the Ariane 4, triggering an overflow set of circumstances that results in the flight computer crashing and over-throttling the engines…followed by the crashing of rocket itself, 40 seconds after launch.

Software News Daily’s list of the 20 worst pieces of software of all time

PC Mag’s list of the 10 worst software disasters,2817,1636333,00.asp

PC World’s list of the 10 worst operating systems of all time

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