Time has passed by the scroll lock key, rendering it the appendix of an IBM-PC computer keyboard. Once, it had a legitimate function: since many monitors could only display 25 lines of text at a time, programming long strings of commands often became problematic. The scroll lock key allowed users to freeze the current screen in place so that the cursor could be easily redirected. Without this function, a programmer working on line 117 might have to manually scroll back to line two for a brief correction. This was time consuming during a complex programming session.
The development of navigational scroll bars eventually rendered this key virtually useless. Some computer games still use it to allow players access to inventories or provide easier navigation through screens, and spreadsheet programs also make use of the function as a form of placeholder — a user may want to visit a previous block of text without losing his current position, for example. For most other modern programming needs, navigational scroll bars and directional cursor arrows largely fulfill this need.
In an effort to keep up with the keyboarding needs of consumers, IBM and others expanded the original keyboard to include directional keys and a single function numerical pad for calculations. This expansion also allowed for separate function keys such as number (or num) lock, scroll lock, caps lock and SysRq. With the exception of the caps lock key, all of these functions have been largely relegated to history. The number lock key has been virtually replaced by separate navigational and numerical entry keypads. The SysRq key never had a function — it was created strictly for a future function that did not materialize.
Many computer keyboards don't include a scroll lock key, although a few do, perhaps for nostalgic purposes.