When was the last time you used the Scroll Lock key? Chances are, unless you’re using 20+ year old hardware, that you haven’t touched it once on your keyboard. Yet, I haven’t seen a mass production keyboard that doesn’t include it. What does it do? Well, not much anymore. ScrollLock is a leftover from the IBM PC, circa 1981. You got it, we have a vestigial key from 30 years ago resting at our fingertips. So the question is, WHAT … DID … IT … DO??? During the days when the mainstream user OS was either DOS or BASIC, the ScrollLock key served as a way to modify how your arrow keys worked in a multiline text interface, such as the BASIC editor. Like CapsLock, it is a toggle button. When off, the arrow keys on the keyboard would move the cursor position in the corresponding direction. When toggled on, rather than moving the cursor, ScrollLock would cause the screen text to scroll up a line or down a line when using the up/down arrows.

So, that’s it? That’s the feature that inspired the rest of the computing world to keep this key around for 30 years? Well, no. There were a few other uses for it as well.

This forgotten key would sometimes come into play on some systems for performing diagnostic tasks as well. Some old operating system would allow system diagnostics by pressing the ScrollLock key during boot, though only a hand full of them ever supported this method.

My favorite information on use of ScrollLock comes from Windows NT systems. By setting the registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\i8042prt\Parameters\CrashOnCtrlScroll to 1, followed by a Ctrl + ScrollLock, a user can force the system to blue-screen on demand.

I’ll  wrap up with a couple debatably useful things you can do you with ScrollLock key.  Are you a Linux user? Good news! ScrollLock can work for you! During a terminal or console session, if you find the text flying by too fast, you can hit the ScrollLock key to freeze it. Depending on the speed of your computer, this may or may not be all that useful as text tends to render pretty quickly.

If you have a KVM switch, you may be in luck as well. KVM switches commonly use the ScrollLock key to switch between connected devices. I haven’t tested this one, personally, but I can imagine it would be very convenient.

In summary, ScrollLock is pretty much a leftover from the personal computer boom in the 80’s. For modern PC’s, it has few uses, with the exception Linux users and KVM switches.