What’s the purpose of the scroll lock key? What does scroll lock do? With modern windowing operating systems we don’t need the scroll lock or scrlk key very often, but it solved a very real problem in the days of DOS.
The scrlk key is an abbreviation for scroll lock. Some keyboards abbreviate it even further. I one keyboard that just says “scr” on that key. However your keyboard abbreviates it, it’s almost always the key in between the print screen and pause keys.
Under MS-DOS, when all we had was a single screen of plain text with one window, we might still want to scroll around the screen rather than moving the cursor. Under Windows or Mac OS, we accomplish that with the arrow gadgets in the corner of each window. That facility didn’t exist in DOS. So instead, we hit Scroll Lock, then hit the arrow keys to move where we wanted.
It wasn’t intuitive. But in 1981, few things were.
The competitive advantage
This gave IBM a competitive advantage in 1981. It was a simple feature, but other computers didn’t have a standard way of doing it. They certainly didn’t have a dedicated key for the purpose. A good salesperson could load up a large document on an IBM PC and another computer. He or she could zoom around the document on the IBM. Then he or she could turn to a cheaper computer and say, “See, I can’t do that on this cheaper computer.”
A less skilled salesperson could at least say the IBM had 83 keys when some competing computers had fewer than 60. What was the advantage? You could type faster and not have to remember as many control-key combinations. It made the IBM PC easier to use, relatively speaking. In 1981 no computer was particularly easy to use by modern standards, so little things like a scroll lock key mattered.
Today, IBM gets remembered as the company that created the PC standard and the industry around it and got chased out due to greed and incompetence. But IBM did a good job of studying the fledgling personal computer industry, asking lots of questions, and designing something that addressed a lot of the shortfalls of the day.
Use by DOS utility programs
That said, even in the 1980s, “what does scroll lock do?” was a fair question. Not a lot of people used the key. It was there, but it probably made for a more impressive sales demo than it did practical, everyday use. It turned out that few enough people used it that DOS utilities could usurp the key to use for other purposes, like copying and pasting between programs. Even people who knew what scroll lock was supposed to do often found these alternatives uses for it more helpful.
What does scroll lock do today?
Today, the best known Windows program that uses functionality similar to this is Excel. A handful of other programs also do it, like Libre Office Calc, which competes with Excel. Probably the second-best known program that uses it is Lotus Notes. If you hit Scroll Lock, you can zoom around the screen with your arrow keys. DOS veterans can find this behavior handy. People who didn’t use the scroll lock key in the 1980s find it confusing. If anything, they hit the key, enable a weird mode, and then they can’t figure out how to get things back to normal.
The other major use for scroll lock today is with KVM switches in server rooms. The scroll lock key activates the KVM, since you’d almost never have any reason to use scroll lock on a server.
Most people regard the Scroll Lock key as a vestigial organ today. Some laptops, such as Lenovo and Dell, bury its functionality in an unmarked key combination like FN+K, FN+C, or FN+S to save space. And usually, unless someone accidentally hits that hidden key combination when trying to do something else, they never miss it.