Editing Guru Meditation (section)

==Technical description (Amiga)== 

When a Guru Meditation is displayed, the options are to [[booting|reboot]] by pressing the left mouse button, or to invoke ROMWack by pressing the right mouse button or to manually reboot. ROMWack is a minimalist [[debugger]] built into the [[operating system]] which is accessible by connecting a 9600 [[bit]]/s terminal to the [[serial port]].

{{multiple image
 | align = right
 | direction = vertical
 | width = 400
 | image1 = Amiga Guru Meditation.gif
 | alt1 = Simulation of the Guru Meditation error message
 | caption1 = Simulation of the Guru Meditation error message
 | image2 = Amiga Recoverable Alert.gif
 | alt2 = Simulation of the Recoverable Alert message
 | caption2 = Simulation of the Recoverable Alert message
}}

The alert itself appears as a black rectangular box located in the upper portion of the screen. Its border and text are red for a normal Guru Meditation, or green/yellow for a Recoverable Alert, another kind of Guru Meditation. The screen may go black, but the power [[LED]]s always alternates between full and half-brightness for a few seconds before the alert appears. In [[AmigaOS]] 1.x, programmed in [[Read-only memory|ROMs]] known as [[Kickstart (Amiga)|Kickstart]] 1.1, 1.2 and 1.3, the errors are always red. In AmigaOS 2.x and 3.x, recoverable alerts are yellow, except for some very early versions of 2.x where they were green.

Dead-end alerts are always red and terminal in all OS versions except in a rare series of events, as in when a deprecated Kickstart (example: 1.1) program conditionally boots from disk on a more advanced Kickstart 3.x ROM Amiga running in compatibility mode (therefore eschewing the on-disk OS) and crashes with a red Guru Meditation but subsequently restores itself by pressing the left mouse button, the newer Kickstart recognizing an inadvised low level chipset call for the older ROM directly poking the hardware, and addressing it.

The error is displayed as two [[field (computer science)|fields]], separated by a period. The format is <code>#0000000x.yyyyyyyy</code> in case of a CPU error, or <code>#aabbcccc.dddddddd</code> in case of a system software error. The first field is either the [[Motorola 68000#Interrupts|Motorola 68000 exception]] number that occurred (if a CPU error occurs) or an internal error identifier (such as an "Out of Memory" code), in case of a system software error. The second can be the address of a ''Task'' structure, or the address of a memory block whose allocation or deallocation failed. It is never the address of the code that caused the error. If the cause of the crash is uncertain, this number is rendered as <code>48454C50</code>, which stands for "HELP" in hexadecimal [[ASCII]] characters (48=H, 45=E, 4C=L, 50=P).

===Guru Meditation handler===
There was a commercially available error handler for AmigaOS, before version 2.04, called GOMF (Get Outta My Face) made by Hypertek/Silicon Springs Development corp. It was able to deal with many kinds of errors and gave the user a choice to either remove the offending process and associated screen, or allow the machine to show the Guru Meditation. In many cases, removal of the offending process gave one the choice to save one's data and exit running programs before rebooting the system. When the damage was not extensive, one was able to continue using the machine. However, it did not save the user from all errors, as one may have still seen this error occasionally.

===Recoverable Alerts===
Recoverable Alerts are non-critical crashes in the computer system. In most cases, it is possible to resume work and save files after a Recoverable Alert, while a normal, red Guru Meditation always results in an immediate reboot.

It is, however, still recommended to reboot as soon as possible after encountering a Recoverable Alert, because the system may be in an unpredictable state that can cause data corruption.{{citation needed|date=November 2011}}

===System software error codes===
The first byte specifies the area of the system affected. The top bit will be set if the error is a dead end alert.{{citation needed|date=October 2011}}

{| class="wikitable"
|-
! Area of system !! Value !! Specific part of system
|-
! rowspan="9" | [[Library (computing)|Libraries]]
| 01 || Exec library
|-
| 02 || Graphics library
|-
| 03 || Layers library
|-
| 04 || [[Intuition (Amiga)|Intuition]] library
|-
| 05 || Math library
|-
| 06 || CList library
|-
| 07 || [[AmigaDOS]] library
|-
| 08 || RAM Handler library
|-
| 09 || [[Icon (computing)|Icons]] library
|-
! rowspan="6" | [[Device driver|Devices]]
| 10 || Audio device
|-
| 11 || Console device
|-
| 12 || Gameport device
|-
| 13 || Keyboard device
|-
| 14 || Trackdisk device
|-
| 15 || Timer device
|-
! rowspan="3" | [[Resource (computer science)|Resources]]
| 20 || [[Complex Interface Adaptor|CIA]] resource
|-
| 21 || Disk resource
|-
| 22 || Misc resource
|-
! rowspan="3" | Other areas
| 30 || [[Booting|Bootstrap]]
|-
| 31 || [[Workbench (AmigaOS)|Workbench]]
|-
| 32 || Diskcopy
|}