Friday, 28 January 2011

The Blue Screen of Death

Windows NT crashed
I am the Blue Screen of Death
No-one hears your screams

— Peter Rothman

Ever since Microsoft began making software, many computers using it have crashed for various reasons, most of which seem to depend upon either how much stress the system is under or how long ago your warranty expired. If unfortunate things happen to your Windows computer, which in all probability they will, then you will get to join the millions of others who are now familiar with the plain blue screen covered in text that has brought so much sorrow to so many.

The text displayed by the blue screen does in fact mean something to a small number of people, namely computer programmers. As well as informing the user that they should reboot their computer and then contact the supplier if the screen appears again, the screen will display technical details including the error name, parameters and number. In the case of the modern Blue Screen of Death (BSoD), the technical details will usually be of the form 'STOP: error number (parameters) error name' — a series of possible errors are listed on the Microsoft website.

History

Windows 1.0 was released in November, 1985, and all Windows operating systems since have been based around the same principles: first, the computer starts its Basic Input/Output System (BIOS), which then boots a nice shiny graphical user interface (GUI). The first versions of Windows did this via MS-DOS1, but Windows 95 and later operating systems all load straight from the bootstrap loader2. This first version of Windows inadvertently brought with it the very first Blue Screen of Death, whereby the blue start-up screen would hang and fill with unintelligible gibberish3 if a bug had stopped the system from booting properly.

The first proper error screens only appeared in 1990 with the release of Windows 3.0, which featured a 'black screen of death'. This indicated that an MS-DOS command had failed, causing the entire screen to turn black and display an error message. Windows 3.1 arrived two years later and included a blue error screen instead of a black one, perhaps as an attempt at making irritating system crashes more enjoyable. It was around this time that the expression 'Blue Screen of Death' first entered use, eventually becoming popularised in 1998, possibly through a haiku written by Peter Rothman for the Salon Haiku Contest, quoted at the top of this Entry. From this unofficial name for the error message comes the verb '(to) blue screen', and a variety of parodies, screensavers and T-shirts. The Blue Screen has since appeared as part of almost every Windows operating system, becoming especially famous for its inclusion in Windows 95.

The Windows 95 Version

Being quite chuffed that they had thought of making their error screens a nice, daunting blue colour, the programmers included it wherever they could in Windows 95. As well as appearing to indicate system failures in which the only solution was to reboot your computer and lose all the hard work you had just done, the system would also get stuck and display the screen due to less problematic things. For instance, if a user removed a CD or floppy disk from its drive before the computer had finished using it, a BSoD would appear demanding that they put it back in, while the BSoD would also appear to reprimand users for pressing Ctrl-Alt-Delete too many times, offering them the choice of simply giving up and rebooting the computer instead of waiting for the system to get its knickers back out of a twist. Various pieces of malignant code could also cause a Blue Screen, including viruses and HTML on websites4.

The reason behind the worst system crashes on Windows 95 was based upon Dynamically Linked Library (DLL) clashes. The probability of such an event occurring increases depending upon what the operating system has been running, as the number of DLL files on a computer increases over usage. In Windows 95, 98 and the Millennium Edition, the Blue Screen of Death is brought up by a fault in the running of a virtual device driver, a piece of software used to make each program think that it is running on its own piece of hardware, thus allowing a computer to cope with multiple processes. The idea of a virtual device driver was replaced by the Windows Driver Model in Windows 2000 and XP, and so the Windows 95 form of the Blue Screen is on its way to being consigned to history. However, this version of the Blue Screen will probably be remembered as the great thorn in Bill Gates' side, after having appeared while Gates was attempting to demonstrate how an early Windows 98 computer could be plugged into a scanner.

The Windows XP Version

Although Windows XP lacks the original Blue Screen, this simply serves to make the BSoD all the more deadly and depressing for those unfortunate enough to see it. The screen is now used to indicate that the kernel, the central part of the operating system which liaises between hardware and software, has done something so unforgivable that the system can no longer cope with itself. Sometimes, the solution is as simple as rebooting the system in Safe Mode and restoring the configurations to those before whatever caused the crash arrived. System Restore, a piece of software bundled with XP, is very useful in these situations, as it can often solve the problem without harming most of your data. If this doesn't help, then the error can be analysed and debugged by those who know how, as whenever a crash occurs the computer will save a 'memory dump' file indicating what it was doing at the time of the crash.

However, life is often nowhere near as simple as this. If the BSoD appears while Windows is booting, the system will immediately reboot and can become stuck in a cycle of rebooting and failing, leaving no memory dump and sometimes making it impossible to read the error message. If using Safe Mode or the Last Known Good Configuration doesn't solve the problem, it is necessary to find a CD with the Windows Recovery Console on it and then use the BIOS to boot the CD5. If using the Recovery Console to repair the boot sector and fix any disk errors doesn't solve the problem, then the system is probably too far gone and will need to have Windows XP reinstalled, a process which will wipe every last bit of useful data from your computer. This sort of BSoD problem is present on all modern versions of Windows — namely 2000, NT, XP and Vista. Those who don't enjoy losing all their work are therefore advised to either back up their work regularly or to start using Linux, an operating system that is much less likely to crash due to the fact that the source code used is open to improvement by anyone who finds a bug.

Other Screens of Death

A wide range of devices found in public spaces use Windows and are capable of showing the BSoD, including Internet-capable payphones and cashpoints, as well as certain TV systems such as TiVo. A Green Screen of Death also exists on Windows XP and is used only to indicate that something really bad has happened and that it would probably be best to completely reinstall Windows. Strangely enough, a Green Screen can also appear on the Microsoft XBox 360 to indicate that it has crashed. A Red Screen of Death was considered for use in indicating a booting error on Windows Vista, but in the meantime can be found displaying on broken Sony PSPs.

Playing With The Blue Screen

It is possible to trigger a BSoD by using Microsoft's Registry Editor to edit the registry setting and then holding Right Ctrl and pressing Scroll Lock twice. Instructions for triggering the screen can be found on the 'plasticbugs' website. It's also possible to trick someone into thinking that they have triggered a BSoD by sending them a full-screen image of one via email. Meanwhile, the colour of the BSoD can be altered to one of sixteen different colours by changing the settings in the SYSTEM.INI file — instructions on how to do this can be found on this website.


1 MicroSoft Disk Operating System — a simple text interface that allowed users to run various commands.
2 The first piece of software loaded by a computer to overcome the problem that loading software requires software.
3 Or at least that's how it appeared to most users.
4 Websites requesting that Windows access the file C:\con\con or C:\nul\nul would crash Windows until a patch was released to fix the problem.
5 If you don't know how to do this, then you'd probably be better off getting someone else to fix your computer for you.

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