Errors or bugs?

For many years the software industry has referred to software errors as bugs. This trivializes the issue, and gives the software developer a false sense of security. (“Once I’ve removed these last few bugs, it will be perfect!”) In reality, the software developer may stand on very shaky ground: “Once I’ve removed these last few bugs, it will be:”

•  a system that has been known to work for 11 minutes continuously... (!)
•  a system that has no written documentation describing it’s architecture...
•  a system that no-one else in the world could repair without spending months looking at my code...
•  a system that still contains code that I put in last month that I don’t know why it is there...
•  a system that stops occasionally, but I can’t reproduce it so lets call it hardware...
•  a system that is still using legacy code that noone has checked for about 12 years, but it has worked for a really long time so it must be OK...
•  a system that is using a commercial windowing package that should be really reliable -well certainly better than code I would produce myself...

The Internet newsgroup comp.risks reports on “Risks to the Public in the Use of Computer Systems and Related Technology”, and makes interesting reading. In the January 1999 risks digest we find that:
From the Toronto ’Globe and Mail’ (Canada) on 22 Jan 1998: Supposedly confidential records of up to 50,000 Canadians were accidentally left accessible to the general public on the Website of Air Miles, Canada’s second largest customer loyalty program.
Previous digests have reported that:

• The Arizona lottery never picked the number 9 (a bad random number generator)
•  The LA counties pension fund has lost US$1,200,000,000 through programming error.
•  Windows NT corrupts filespace and deletes directories under some circumstances.
•  A Mercedes 500SE with graceful no-skid brake computers left 200 metre skid marks. A passenger was killed.
•  A woman killed her daughter, and attempted to kill herself and her son, after a computer error led to her being told that all her family had an incurable cancer.
• A computer controlled elevator door in Ottawa killed two people.
• An automated toilet seat in Paris killed a child. 
• The Amsterdam air-freight computer software crashed, killing giraffes.
• Two Russ Hamilton’s had the same birthdate. The wrong one was jailed as a result of a software error.
•  A software patch to an unrelated system miraculously added $10 to $30 to 300,000 auto tax bills in Georgia.
•  The Panasonic children’s Internet watchdog software regularly spews out vulgarities.
•  General Motors recalled over 1,000,000 cars for a software change to stop erratic air bag deployment.
•  The 22nd of August 1999 might be a very dangerous date - don’t rely on GPS or the time on that day.

There are thousands more of these sort of stories documented over the last 20 or so years, and in
the following section we look at just one.