Word processors never display a cursor. You never have to use the space-bar when typing long sentences.
All monitors display inch-high letters.
High-tech computers, such as those used by NASA, the CIA, or some such governmental institution, will have easy to understand graphical interfaces. Those that don't, have incredibly powerful text-bases command shells that can correctly understand and execute commands typed in plain English. All computers are connected. You can access the information on the villain's desktop computer, even if it's turned off. Powerful computers beep whenever you press a key or whenever the screen changes.