The Blue Screen of Death (sometimes called "bluescreen", "stop error" or just abbreviated as "BSoD") is a popular name for the screen displayed by Microsoft's Windows operating system when it cannot recover from, or is in danger of being unable to recover from, a system error. There are two Windows error screens that are both referred to as the blue screen of death, with one (Windows NT 4/2000/XP) being significantly more serious than the other (Windows 9x).

The blue screen of death in one form or another has been present in all Windows operating systems since Windows version 3.1. It is the successor of the less well-known black screen of death that occurs in OS/2 as well as MS-DOS. In early builds of Windows Vista it was complemented with the red screen of death, used for boot loader errors.

The term "blue screen of death" was coined by Erik Noyes while he worked for Charles Schwab and Co., Inc.'s technical support for the Electronic Service Delivery division in early 1991. At the time, he and the ESD team were supporting Schwab's DOS program, Equalizer on Microsoft Windows 3.0. Running DOS programs in this new environment was as challenging as one would expect - for the ESD Support Team as well as the thousands of customers who were also attempting run the DOS program in this Windows environment. .PIF files were a good solution to prevent the blue screen of death, but inevitably it would occur at the worst possible time, and a general term was needed to describe the symptom. Erik coined this phrase and shared it with customers and his co-workers. Soon, it became the standard term within Schwab and among Schwab customers who called in with the symptoms described in this article.

Types of BSoDs

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Windows NT/2000/XP

In Windows NT, Windows 2000, and Windows XP, a blue screen of death occurs when the kernel or a driver running in kernel mode, encounters an error from which it cannot recover. This is usually caused by an illegal operation being performed. The only safe action the operating system can take in this situation is to restart the computer. As a result, data may be lost, as users are not given an opportunity to save data that has not yet been saved to the hard drive.

Blue screens are known as "Stop errors" in the Windows Resource Kit documentation. They are referred to as "bug checks" in the Windows Software development kit and Driver development kit documentation.

The text on the error screen contains the code of the error as well as its symbolic name (e.g. 0x0000001E, KMODE_EXCEPTION_NOT_HANDLED) along with four error-dependent values in parentheses that are there to help software engineers with fixing the problem that occurred. Depending on the error code, it may display the address where the problem occurred, along with the driver which is loaded at that address. Under Windows NT and 2000, the second and third sections of the screen contain information on all loaded drivers and a stack dump, respectively. The driver information is in three columns; the first lists the base address of the driver, the second lists the driver's creation date (as a Unix timestamp), and the third lists the name of the driver ..

By default, Windows will create a memory dump file when a blue screen error occurs. Depending on the OS version, there may be several formats this can be saved in, ranging from a 64 KB "minidump" to a "complete dump" which is effectively a copy of the entire contents of physical RAM. The resulting memory dump file may be debugged later, using a kernel debugger. A debugger is necessary to obtain a stack trace, and may be required to ascertain the true cause of the problem; as the information onscreen is limited and thus possibly misleading, it may hide the true source of the error.

Microsoft Windows can also be configured to send live debugging information to a kernel debugger running on a separate computer. (Windows XP also allows for kernel debugging from the machine that is running the OS.) If a blue screen error is encountered while a live kernel debugger is attached to the system, Windows will halt execution and cause the debugger to "break in", rather than displaying the BSoD. The debugger can then be used to examine the contents of memory and determine the source of the problem.

The Windows debugger is available as a free download from Microsoft.

Windows includes a feature that can be used to manually cause a blue screen. To enable it, the user must add a value to the Windows registry. After that, a BSoD will appear when the user presses the SCROLL LOCK key twice while holding the right CTRL key. This feature is primarily useful for obtaining a memory dump of the computer while it is in a given state. As such, it is generally used to aid in troubleshooting system hangs.

A BSoD can also be caused by a critical boot loader error, where the operating system is unable to access the boot partition due to incorrect storage drivers or similar problems. The error code in this situation is STOP 0x0000007B (INACCESSIBLE_BOOT_DEVICE). In such cases, there is no memory dump saved. Since the system is unable to boot from the hard drive in this situation, correction of the problem often requires booting from the Microsoft Windows CD. After booting to the CD, it may be possible to correct the problem by performing a repair install or by using the Recovery Console (with CHKDSK).

ReactOS

ReactOS, an attempt at creating an open-source implementation of a Windows NT-compatible operating system, also features its own BSoD similar to the Windows NT one (see the gallery below).

Windows 9x/Me

The blue screen of death also occurs in Microsoft's home desktop operating systems Windows 95, 98, and Me. Here it is less serious, but more common. In these operating systems, the BSoD is the main way for virtual device drivers to report errors to the user. It is internally referred to by the name of "_VWIN32_FaultPopup". A Windows 9x/Me BSoD gives the user the option to either restart or continue. However, VxDs do not display BSoDs frivolously—they usually indicate a problem which cannot be fixed without restarting the computer, and hence after a BSoD is displayed the system is usually unstable or unresponsive.

The most common reason for BSoD's is that problems occur with incompatible versions of DLLs. This cause is sometimes referred to as DLL hell. Windows loads these DLLs into memory when they are needed by application programs; if versions are changed, the next time an application loads the DLL it may be different from what the application expects. These incompatibilities increase over time as more new software is installed, and is one of the main reasons why a freshly-installed copy of Windows is more stable than an "old" one.

In Windows 95 and 98, a BSoD occurred when the system attempted to access the file "c:\con\con" on the hard drive. This was often inserted on websites to crash users' machines. Microsoft has released a patch for this.

The BSoD can appear if a user ejects a removable medium while it is being read on 9x/ME. This is particularly common while using Microsoft Office: if a user simply wants to view a document, he might eject a floppy disk before exiting the program. Since Microsoft Office always creates a temporary file in the same directory, it will trigger a BSoD upon exiting because it will attempt to delete the file on the disk that is no longer in the drive.

This type of blue screen is no longer seen in Windows NT, 2000, and XP. In the case of these less serious software errors, the program may still crash, but it will not take down the entire operating system with it due to better memory management and decreased legacy support. In these systems, the "true" BSoD is seen only in cases where the entire operating system crashes.

Windows CE

The simplest version of the blue screen occurs in Windows CE, but not in Windows CE for Pocket PC. The blue screen in Windows CE 3.0 is similar to the one in Windows 95 and 98.

Display

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By default, the display is white (EGA color 0x0F; HTML color #FFFFFF) lettering on a blue (EGA color 0x01; HTML color #0000AA) background, with information about current memory values and register values. For visually impaired users, Microsoft has added a utility that allows the user to change a setting in system.ini that controls the colors that the BSoD code uses to any of the 16 EGA colors.

Windows 95, 98 and Me use 80x25 text mode. The font is identical to Fixedsys. The Windows NT BSoD uses 80x50 text mode. The screen resolution is 720x400. The XP BSoD uses font Lucida Console.

Red screen of death

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The Red Screen of Death (abbreviated RSoD, sometimes called "Red Screen of Doom") is a nickname for the error message which exists in some beta versions of Microsoft's upcoming operating system, Windows Vista. It was dropped in Build 5112 of Windows Vista. It can also be found (but rarely) in versions of Microsoft's Windows 98 operating system.

The red screen of death appeared when boot loader errors occurred. Windows Vista continues to have blue screens for other types of errors.

The red screen of death also sometimes refers to fatal errors in recent versions of Lotus Notes. These errors are not full-screen like the Microsoft red or blue screens of death, but rather are bright red boxes with black borders. The RSoD uses 80×25 text mode, with a screen resolution of 640×400 and a font similar to Fixedsys.

Blue screens in the IT industry

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System administrators often use "to bluescreen" or "to BSoD" as a verb, as in: "The server just bluescreened", "Oh, great, it's going to BSoD", or "Windows 2000 doesn't bluescreen as much as NT 4 did."

Embedded systems running Microsoft Windows NT Embedded and Windows XP Embedded have also been known to Bluescreen. Typical examples are Internet payphones, automatic teller machines and information displays.

On an unpatched Windows 95 or Windows NT 4.0 system, it is possible for a BSoD to occur as a result of WinNuke, a type of internet attack.

Understanding the Blue Screen of Death

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Each BSoD usually displays a message such as FILE_SYSTEM as well as a number like 0x00000022. The usual parameters displayed for the BSoD are the following:

number of error (parameter, parameter, parameter, parameter) name of error

Knowing all of the above information is important in understanding and determining the cause of the BSoD.http://msdn.microsoft.com/library/default.asp?url=/library/en-us/w2kmsgs/1117.asp

Well-known references to the blue screen of death

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Perhaps the most famous BSoD event occurred when Bill Gates was himself unveiling the then-new Windows 98 at COMDEX on April 20 1998. The demo PC crashed with a BSoD when his assistant connected a scanner to the PC. (Video can be viewed here.) This event brought thunderous applause from the crowd and considerable embarrassment to Microsoft. Gates only limited himself to say, "That must be why we're not shipping Windows 98 yet."

As the BSoD is often subject to jokes and gags, it was also "introduced" to other system platforms as part of screensavers.

Microsoft has also included a reference to the BSoD as an Easter egg in the Internet Explorer browser (versions 4 through 7). Typing "about:mozilla" in the address bar will result in a blank blue page being displayed. However, this has been removed with Service Pack 2 but it can still be shown by typing "res://mshtml.dll/about.moz" instead. The command is the standard way to bring up The Book of Mozilla, another Easter egg on the Netscape/Mozilla family of browsers.

Several online vendors sell blue T-shirts that re-create the BSoD, and BSoDs commonly appear in video games and webcomics.

On the PlayStation Portable, when something botches its "/flash0:" directory, it displays the "BSoD", prompting you to reset its system to the default factory settings.

In Dual Strike, Black Hole CO Jugger speaks in very technical diction; "blue screen of death" is one of the sayings he might use when initiating a Tag Attack/Dual Strike or CO Power.

One of the sanity effects of Sanity's Requiem involves abruptly displaying a BSoD during a battle or tense scene. It appears for only a few seconds, before the screen flashes white, returning to the actual game.

In the Halo 2 multiplayer map Zanzibar, opening the gate from the control panel causes the panel to display a spoof blue screen and in Delta Halo & High Charity.

In Irregular Webcomic the crew of the sci fi ship have a computer that steals unused runtime from past computers using time travel. When asked "Is it safe?" Spanners can barely finish his reply before the Blue Screen of Death comes up.

In the game Startopia, workstations in the lab can sometimes be seen experiencing BSoD. (Causing the Turraken staff to bash the machines soundly.)

In the Boy Genius episode called Sleepless in Retroville, Jimmy says "I can't get rid of it, the screen is frozen." and it shows the blue screen of death.

In the computer game Half-Life, in the chapter "Anomalous Materials" (at the very start of the game), there is a guard at a desk working on a computer with a blue screen, and he talks to the player about a system crash before telling them to go on there way as they are already late. He says, 'we had a system crash about half an hour ago and I'm still tryin' to find my files. Just one of those days I guess...'.

In American McGee Presents Scrapland, a human software salesman appears midway through the game, and tells you that "If I install our software on your machine, it will destroy your software." This is necessary to complete the game, and after he does, all indoor screens which used to display news now show a BSOD.

In SWAT 4 and The Stetchkov Syndicate almost every PC screen in the game shows a blue screen of death. There are many examples of this in the Red Library Offices, particularly in the server rooms.

In the computer game The Masquerade - Bloodlines, in one of the "Nosferatu Warrens" levels, there is a computer you must activate to open a hatchway to the lowest Warrens levels. The screen of that computer shows a satirical variant of the blue screen of death.