A public payphone that has experienced a fatal error causing a crash and is displaying the Blue Screen of Death.

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A crash (or system crash) in computing is a condition where a computer or a program, either an application or part of the operating system, ceases to function properly, often exiting after encountering errors. Often the offending program may appear to freeze or hang until a crash reporting service documents details of the crash. If the program is a critical part of the operating system kernel, the entire computer may crash. This is different from a hang or freeze where the application or OS continues to run without obvious response to input.

Many crashes are the result of the execution of a single machine instruction, but the causes of this are many fold. Typical causes are when the program counter is set to an incorrect address or a buffer overflow overwrites a portion of program code due to an earlier bug. In either case, it is quite common for the processor to attempt to execute data or random memory values. Since all data values are possible but only some values are valid instructions, this often results in an illegal instruction exception. By chance such data or random values could be valid (though unplanned) instructions. One might say that the original bug that upset the program counter "caused" the crash, but the actual fault was an illegal instruction some time later. The art of debugging such crashes is connecting the actual cause of the crash (easily determined) with the code that set off the chain of events. This is often very far from obvious—the original bug is usually perfectly valid code from the processor's perspective.

On earlier personal computers, it was actually possible to cause hardware damage through trying to write to hardware addresses outside of the system's main memory. Occasionally, execution of arbitrary data on a system will result in a breakup of screen display. This is widely considered a severe system crash.

Etymology[link]

The term "crash" may originate from the phrase "head crash", which occurs when the read/write heads inside a hard disk physically come into contact with--"crash" into—the platter, the magnetic data storage surface of a hard disk. A head crash is catastrophic to the drive operation, roughly analogous to the severity of a computer crash to computer software.

Application crashes[link]

An application typically crashes when it performs an operation which is not allowed by the operating system. The operating system then triggers an exception or signal in the application. Unix applications traditionally responded to the signal by dumping core. Most Windows and Unix GUI applications respond by displaying a dialog box (such as the one shown to the right) with the option to attach a debugger if one is installed. This behavior is called "crashing". Some applications attempt to recover from the error and continue execution instead of crashing.

Typical errors that result in application crashes include:

• attempting to read or write memory that is not allocated for reading or writing by that application (segmentation fault) or x86 specific (general protection fault)
• attempting to execute privileged or invalid instructions
• attempting to perform I/O operations on hardware devices to which it does not have permission to access
• passing invalid arguments to system calls
• attempting to access other system resources to which the application does not have permission to access (bus error)
• attempting to execute machine instructions with bad arguments (depending on CPU architecture): divide by zero, operations on denorms or NaN values, memory access to unaligned addresses, etc.

Website server crashes[link]

The software running the server behind a website may crash, rendering it inaccessible entirely or providing only an error message instead of normal content.

For example: If a site was using a SQL database (such as MySQL) for a script (such as php) and that SQL server crashed, then php would display a connection error.

Operating system crashes[link]

An operating system crash commonly occurs when a hardware exception occurs that cannot be handled. Operating system crashes can also occur when internal sanity-checking logic within the operating system detects that the operating system has lost its internal self-consistency.

Modern multi-tasking operating systems, such as Windows NT, Linux, or Mac OS X usually remain unharmed when an application program crashes.

See also[link]

• Blue Screen of Death
• Crash to Desktop
• Segmentation fault
• Safe Mode
• Debugging
• Kernel panic
• Reboot
• Crash reporter
• Data loss
• SystemRescueCD

Look up crash in Wiktionary, the free dictionary.

Crash may refer to:

Sudden events[link]

• Collision, an impact between two moving objects
  • Traffic collision, also known as a car crash
  • Aviation accidents and incidents, airplane crash
• Crash (computing), a condition where a program ceases to respond
  • Head crash, in which a hard disk drive's read-write head physically collides with the disk
• Stock market crash, a sudden dramatic decline of stock prices
• Cardiac arrest, a medical condition in which the heart stops beating

Film[link]

• Crash (1974 film), a Norwegian drama directed by Rolf Clemens
• Crash!, a 1977 suspense drama starring José Ferrer and Sue Lyon
• Crash (1978 film), a made-for-TV docudrama starring William Shatner and Adrienne Barbeau
• Crash (1996 film), a drama directed by David Cronenberg
• Crash (2004 film), a drama directed by Paul Haggis and winner of the 2005 Academy Award for Best Picture

Television[link]

• Crash (1984 TV series), a Danish science fiction series
• Crash (2008 TV series), an American drama based on the 2004 film
• Crash (2009 TV series), an English-language Welsh medical drama series
• "The Crash" (Life on Mars), an erroneous title for the first episode of Life on Mars
• "Crashers" (Law & Order), a 2010 episode of the NBC long-running legal drama, Law & Order

Books and magazines[link]

• Crash (J. G. Ballard novel) by J. G. Ballard, the basis of the 1996 film
• Crash (Spinelli novel), by Jerry Spinelli
• Crash (magazine)

Music[link]

Performers[link]

• Crash (South Korean band)
• Crash (UK band)
• The Crash (band), a Finnish pop rock band
• Billy "Crash" Craddock, country music singer
• Darby Crash, punk rock musician
• Crash (drummer), member of the Swedish hard rock band H.E.A.T

Albums[link]

• Crash (Billy "Crash" Craddock album)
• Crash (Dave Matthews Band album)
• Crash (Human League album)
• Crash (Decyfer Down)

Songs[link]

• "Crash" (Feeder song)
• "Crash" (Gwen Stefani song)
• "Crash" (The Primitives song)
• "Crash" (Royseven song)
• "Crash" (Cavo song)
• "Crash!", a song by Propellerheads
• "Crash", a song by Anthrax from We've Come for You All
• "Crash", a song by Methods of Mayhem from Methods of Mayhem (album)
• "Crash", a song by Mephisto Odyssey, featuring Static-X
• "Crash", a song by Aerosmith from Nine Lives (Aerosmith album)
• "Crash", a song by Sum 41 from the album Screaming Bloody Murder

Instruments[link]

• Crash cymbal

Gaming[link]

• Crash Bandicoot (video game)
• crash 2 ps1
• crash 3 ps1 (racing game)
• Crash (card game)
• CRASH convention, a concept in the game of contract bridge
• Crash Bandicoot (disambiguation), various meanings relating to a video game
• Crash, a character in the video game Crash 'n the Boys: Street Challenge
• Hot Wheels: Crash!, a video game released in 2000 for Microsoft Windows
• Crash, a character in the video game Quake 3
• Burnout Crash!, a video game released in 2011 for PlayStation Network (PlayStation 3) and Xbox Live Arcade (Xbox 360), with the Xbox 360 version being Kinect-enhanced

People with the given name Crash[link]

• Crash (graffiti artist) or John Matos (born 1961), American graffiti artist
• Crash Holly or Mike Lockwood (1971–2003), American professional wrestler
• "Crash", a nickname of American Olympic pole vaulter Toby Stevenson
• Gerald "Crash" Wallace, a forward for the NBA's Portland Trail Blazers.

Other uses[link]

• Community Resources Against Street Hoodlums, a unit of the Los Angeles Police Department
• A group of rhinoceroses
• The act of gate-crashing, entering an event without invitation
  • Wedding crashing, attending a wedding without an invitation
• The negative effect of a drug; the comedown (drugs)
• Crash, a plain linen fabric used for towels.
• Iowa City Crash, a Rugby League team from Iowa City, IA, USA

See also[link]

• "Crashed" (Daughtry song)
• "Crashing" (Unloco song), a song by Unloco

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