Engineers have for example been attributing many of the “unexplainable” errors, flaws and imperfections of technology directly to the presence of bugs. So what is a computer bug and what can we do about it?

Figure 1: Computer Bugs

Bug

In computer circles a computer bug (including bugs of both hardware and/or software origin) is an unplanned error, flaw, failure or other (usually undocumented) aspect that prevents the machine from behaving as intended.

The cause of the production of these incorrect answers/results and unwanted behaviors by computers can often be directly attributable to computer bugs of one type or another.

Buggy

The term “Buggy” refers to software and hardware components containing large numbers of bugs. Their performance, reliability and trustworthiness are thus not 100% guaranteed are all times.

Bug Reports

Names given to reports dealing with bug related issues vary depending on your current locale and include bug report(s), fault report(s), trouble report(s) and change request(s).

Issues not Bugs

It is a question of semantics. The term “bug” has been in common usage by engineers for quite some time now but many organizations and developers deliberately avoid using the term.

One reason recently cited for this is as a direct result of the negative baggage that accompanies the term. Microsoft for example uses the term “issues” in replacement of “bugs”.

Computer Bug Origins

The origins of the term “computer bugs” stretch back a long way. Some of the events, circumstances and people put forward as being the source of the term “bug/bugs” differ considerably.

One popular tale that does have some basis in fact concerns an early computer pioneer named Grace Hopper, who back in 1947, was working on a system called the Mark II (an early electromechanical computer).

She is supposed to have found a moth trapped in a relay among the computer's vacuum tubes. Hopper readily concedes that she was not the one who actually found the moth.

She was however, the one who publicized the event. It would seem that the operators who did find the moth were familiar with the use of the engineering term “bug” and thought it amusing to tape the moth to their report of the incident with the following notation "First actual case of bug being found." See Fig. 2.

Figure 2: “First actual case of bug being found.”

We know that the term “bug” was used during World War II to refer to faults and issues with the development of radar electronics. In fact, engineers were using the term “bug” in relation to defects long before the Hopper event. For example, early 1890s editions of the Oxford English Dictionary included the following quotation from an 1889 edition of the Pall Mall Gazette:

“Mr. Edison, I was informed, had been up the two previous nights discovering "a bug" in his phonograph-an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble”.

Figure 3: Thomas Edison

The Mr. Edison (Fig. 3) referred to here is none other than Thomas Alva Edison. Edison was one of the first inventors to apply the principles of mass production to the process of invention. He is therefore is often credited with the creation of the first industrial research laboratory.

Human Error

Bugs generally result from human error somewhere along the way. The design, product development and production implementation stages of all forms of computer technologies are the major areas in which bugs tend to creep into the system. They also happen to be the areas in which human involvement is maximal.

Hardware Bugs

While a larger percentage of computer bugs have their basis in software, there are still many instances where hardware is at fault. As with any other piece of hardware a computer's hardware can components can fail, thereby producing erroneous results.

Events from the past show that it is also possible for the computer hardware to have bugs built into them (we must assume not deliberately). A classical case of this was the Pentium FDIV bug.

Back in the early 1990s, a number of Intel Pentium processors contained hardware errors that resulted in erratic performance and unreliable computation of floating point division operations. The result was that Intel had to recall a considerable number of the faulty Pentium processors.

Impact

The consequences resultant from bugs varies considerably in terms of the severity of impact. They also vary in terms of frequency and in their potential to produce far-flung collateral damage.

Some bugs are innocuous due directly to their minimal impact or rarity. Others are quite noticeable as a direct result of their capacity to interfere with a system's functionality and responsiveness.

Then we have that most critical group of bugs that render systems inoperable or contribute directly to fatalities. One such event occurred during the 1980s when a bug in the code controlling the Therac-25 radiation therapy machine was directly responsible for some patient deaths.

Another more disconcerting incident in 1983 nearly caused World War III. This incident was a direct result of software bugs in the Soviet Union's early warning system.

The early warning system falsely reported that the US had launched five Intercontinental Ballistic Missiles (ICBMs) armed with nuclear warheads and their current course and trajectory indicated that they were heading towards targets in the Soviet Union.

Fortunately, the system duty officer at the time, Lt Col Stanislav Petrov, questioned the warning by reasoning that if the US were in deed launching a pre-emptive strike they would most certainly be sending more than five ICBMs.

The cause of the fault was faulty software, ironically meant to filter out false positive missile detections caused by satellites detecting sunlight reflections off cloud-tops.

Figure 4: Intercontinental Ballistic Missile (ICBM) Launch

In June 1994, a Royal Air Force Chinook crashed into the Mull of Kintyre, killing 29 people. On closer investigation, the accident, originally attributed to pilot error, proved to be due to a software bug in the aircraft's engine control computer.

Then in 1996, a bug in the on-board guidance computer program of the European Space Agency's unmanned US$1 billion prototype Ariane 5 satellite-launching rocket saw the rocket self-destruct less than a minute into its maiden flight. The rocket launch site was Kourou, French Guiana.

On board were four scientific satellites designed and purpose built to study the interactions between the Earth's magnetic fields and Solar Winds. The four satellites cost over US$500 million. This particular computer bug cost in excess of US$1.5 billion on top of the US$8 billion already spent in developing the Ariane 5 rocket.

The European Space Agency had now invested over US$9.5 billion and was yet to see any return.

Leading up to the year 2000 we saw quite a stir concerning the Millennium Bug. This one was due to using a two-digit year naming system. While acceptable for early machines that had very limited memory and storage capacities this bug/issue should have seen full resolution long before the year 2000 when there was no alternative. You cannot stop time.

Today

Today we find that the term bug in respect to computers has taken on a completely new meaning. If you were to contract the influence virus or a stomach upset, you might say to your doctor, employer, colleagues, friends or family “I seem to have caught a bug” or “I have come down with a tummy bug”.

Computers can also catch bugs, which usually come in the form of a computer virus. Just as there are numerous “strains” of the influenza virus so too are there many different species of computer viruses.

Here is a list of some of them. I have compiled this list alphabetically and not upon such criteria as damage done, prevalence, epidemiology, persistence, dollars and frequency and geographical distribution.

Application and File Viruses (e.g. email, document, embedded etc.), Boot Sector Viruses, Combination Viruses, Hoax Viruses, Operating System (OS) Viruses, Polymorphic Viruses, Rootkits, Spyware, Trojan Horses and Worms