It may still work when in system bootup screen, and is also used in spread sheet to force arrow keys to scroll window instead moving around cells.

ScrollLock (Scroll Lock) → Used to toggle the behavior of arrow keys so that, when ScrLk is on, the up/down arrows scrolls the window. Unlike most keys, when it is pressed nothing is stored in the keyboard buffer. A special BIOS routine – software interrupt 0x15, subfunction 0x85 – was added to signal the OS when SysRq was pushed or released. Introduced by IBM with the PC/AT, it was intended to be available as a special key to directly invoke low-level operating system functions with no possibility of conflicting with any existing software. System request (often abbreviated SysRq or Sys Req) is a key on personal computer keyboards that has no standard use. Some programing applications still use it, to reboot, reset, or enter debug mode, for example: It is used by Linux kernel developers Magic SysRq key, and some IDEs. SysRq causes a interrupt to the operating system. SysRq is usually shared with the PrintScreen key. Unicode has a character to represent print screen: You open a image program such as Microsoft Paint then paste it.). (It copies screen image into the clipboard. Today, PrintScreen key is used in Windows and Linux to do screenshot. (at the time, most monitors can only display text.) In 1990s or earlier, it sends the screen's text into the printer port (LPT1), causing the screen to be printed. (on the Mac, it's done by ⌘ command+ Shift+ 3) Print Screen Key They don't have a standard purpose today,Įxcept the Print Screen key is used for creating screenshots in Microsoft Windows and Linux. Microsoft Natural Ergonomic Keyboard 4000 PrintScreen, SysRq, ScrollLock, Pause, Break Break keys were relics from 1980s and 1990s.

Print screen key on mac keyboard