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From The Jargon File (version 4.4.7, 29 Dec 2003) :
An unwanted and unintended property of a program or piece of hardware, esp.
one that causes it to malfunction. Antonym of feature. Examples: ?There's
a bug in the editor: it writes things out backwards.? ?The system crashed
because of a hardware bug.? ?Fred is a winner, but he has a few bugs?
(i.e., Fred is a good guy, but he has a few personality problems).
Historical note: Admiral Grace Hopper (an early computing pioneer better
known for inventing COBOL) liked to tell a story in which a technician
solved a glitch in the Harvard Mark II machine by pulling an actual
insect out from between the contacts of one of its relays, and she
subsequently promulgated bug in its hackish sense as a joke about the
incident (though, as she was careful to admit, she was not there when it
happened). For many years the logbook associated with the incident and the
actual bug in question (a moth) sat in a display case at the Naval Surface
Warfare Center (NSWC). The entire story, with a picture of the logbook and
the moth taped into it, is recorded in the Annals of the History of
Computing, Vol. 3, No. 3 (July 1981), pp. 285--286.
The text of the log entry (from September 9, 1947), reads ?1545 Relay #70
Panel F (moth) in relay. First actual case of bug being found?. This
wording establishes that the term was already in use at the time in its
current specific sense ? and Hopper herself reports that the term bug was
regularly applied to problems in radar electronics during WWII.
The ?original bug? (the caption date is incorrect)
Indeed, the use of bug to mean an industrial defect was already established
in Thomas Edison's time, and a more specific and rather modern use can be
found in an electrical handbook from 1896 (Hawkin's New Catechism of
Electricity, Theo. Audel & Co.) which says: ?The term ?bug? is used to a
limited extent to designate any fault or trouble in the connections or
working of electric apparatus.? It further notes that the term is ?said to
have originated in quadruplex telegraphy and have been transferred to all
The latter observation may explain a common folk etymology of the term;
that it came from telephone company usage, in which ?bugs in a telephone
cable? were blamed for noisy lines. Though this derivation seems to be
mistaken, it may well be a distorted memory of a joke first current among
telegraph operators more than a century ago!
Or perhaps not a joke. Historians of the field inform us that the term ?bug
? was regularly used in the early days of telegraphy to refer to a variety
of semi-automatic telegraphy keyers that would send a string of dots if you
held them down. In fact, the Vibroplex keyers (which were among the most
common of this type) even had a graphic of a beetle on them (and still do)!
While the ability to send repeated dots automatically was very useful for
professional morse code operators, these were also significantly trickier
to use than the older manual keyers, and it could take some practice to
ensure one didn't introduce extraneous dots into the code by holding the
key down a fraction too long. In the hands of an inexperienced operator, a
Vibroplex ?bug? on the line could mean that a lot of garbled Morse would
soon be coming your way.
Further, the term ?bug? has long been used among radio technicians to
describe a device that converts electromagnetic field variations into
acoustic signals. It is used to trace radio interference and look for
dangerous radio emissions. Radio community usage derives from the
roach-like shape of the first versions used by 19th century physicists. The
first versions consisted of a coil of wire (roach body), with the two wire
ends sticking out and bent back to nearly touch forming a spark gap (roach
antennae). The bug is to the radio technician what the stethoscope is to
the stereotypical medical doctor. This sense is almost certainly ancestral
to modern use of ?bug? for a covert monitoring device, but may also have
contributed to the use of ?bug? for the effects of radio interference
Actually, use of bug in the general sense of a disruptive event goes back
to Shakespeare! (Henry VI, part III - Act V, Scene II: King Edward: ?So,
lie thou there. Die thou; and die our fear; For Warwick was a bug that
fear'd us all.?) In the first edition of Samuel Johnson's dictionary one
meaning of bug is ?A frightful object; a walking spectre?; this is traced
to ?bugbear?, a Welsh term for a variety of mythological monster which (to
complete the circle) has recently been reintroduced into the popular
lexicon through fantasy role-playing games.
In any case, in jargon the word almost never refers to insects. Here is a
plausible conversation that never actually happened: ?There is a bug in
this ant farm!? ?What do you mean? I don't see any ants in it.? ?That's the
A careful discussion of the etymological issues can be found in a paper by
Fred R. Shapiro, 1987, ?Entomology of the Computer Bug: History and
Folklore?, American Speech 62(4):376-378.
[There has been a widespread myth that the original bug was moved to the
Smithsonian, and an earlier version of this entry so asserted. A
correspondent who thought to check discovered that the bug was not there.
While investigating this in late 1990, your editor discovered that the NSWC
still had the bug, but had unsuccessfully tried to get the Smithsonian to
accept it ? and that the present curator of their History of American
Technology Museum didn't know this and agreed that it would make a
worthwhile exhibit. It was moved to the Smithsonian in mid-1991, but due to
space and money constraints was not actually exhibited for years
afterwards. Thus, the process of investigating the original-computer-bug
bug fixed it in an entirely unexpected way, by making the myth true! ?ESR]
It helps to remember that this dates from 1973.
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