System request
System Request (SysRq or Sys Req) is a key on
History
The specific low level function intended for the SysRq key was to switch between operating systems. When the original IBM-PC was created in 1980, there were three leading competing operating systems:
A special key was needed because most
On 84-key keyboards (except the 84-key IBM Model M space saver keyboard), SysRq was a key of its own. On the later 101-key keyboard, it shares a physical key with the
The default BIOS keyboard routines simply ignore SysRq and return without taking action. So did the
On the
Modern uses
In Linux, the kernel can be configured to provide functions for system debugging and crash recovery.[5] This use is known as the "magic SysRq key".
Microsoft has also used SysRq for various OS- and application-level debuggers. In the CodeView debugger, it was sometimes used to break into the debugging during program execution.[6] For the Windows NT remote kernel debugger, it can be used to force the system into the debugger.[7]
On modern Windows "
Similar keys
See also
- Serial console
- Break key
- Scroll Lock
References
- ^ "Ralf Brown's Interrupt List". Retrieved 2018-06-21.
- ^ "Original IBM PC Product fact sheet". IBM Information Systems Division. August 12, 1981. Retrieved January 13, 2010.
- ^ Personal interview with Sandy Meade, creator of the SysRq key
- ^ a b "What Are the Sys Rq, Scroll Lock, and Pause Break Keys on My Keyboard?". Retrieved March 2, 2020.
- ^ "Linux Magic System Request Key Hacks". Linux kernel. Retrieved 2018-06-21.
- ^ "Returning Control to CodeView". Microsoft Knowledge Base. Archived from the original on November 8, 2008. Retrieved January 8, 2008.
- ^ "How to enable a remote kernel debugger connection on a computer that is running Windows Server 2003 with Service Pack 1". Microsoft Knowledge Base. Archived from the original on October 21, 2012. Retrieved January 8, 2008.
- ^ "Copy the window or screen contents". Retrieved March 2, 2020.
External links
- Media related to System request at Wikimedia Commons
Esc | F1 | F2 | F3 | F4 | F5 | F6 | F7 | F8 | F9 | F10 | F11 | F12 | PrtScn/ SysRq |
Scroll Lock |
Pause/ Break |
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Insert | Home | PgUp | Num
Lock |
∕ | ∗ | −
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Delete | End | PgDn | 7 | 8 | 9 | +
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4 | 5 | 6 | ||||||||||||||||||||||
↑ | 1 | 2 | 3 | Enter | ||||||||||||||||||||
← | ↓ | → | 0 Ins |
. Del |