SysRq

SysRq is one of the greatest mysteries of all time. SysRq used to have it's own key, but now it has been forced into sharing with Print Screen. SysRq is bitter because of this, and many fondue sets have been tarnished due to SysRq's poor attempts to curry the favour of it's fellow victims Pause Break and Scroll Lock. SysRq is currently working on a novel, however since it has no hands, progress has been slow.

Together with Scroll Lock, Insert and Pause/Break, SysRq (short for System Request) is one of the atavisms in modern personal computers. Harking back to those optimistic days of innocent enthusiasm when each key had a Purpose, and often a glorious one, these keys now exist merely for backwards compatibility. Yup. Just like Windows.

SysRq - usurp console input from the active program and redirect to the OS shell
Pause - pause running program
Break - stop execution, return to OS shell
Ins - toggle between insert/overwrite text entry modes