Commodore 64 and Ataris had intelligent peripherals. Commodore’s drive knew about the filesystem and could stream the contents of a file to the computer without the computer ever becoming aware of where the files were on the disk. They also could copy data from one disk to another without the computer being involved.

Mainframes are also like that - while a PDP-11 would be interrupted every time a user at a terminal pressed a key, IBM systems offloaded that to the terminals, that kept one or more screens in memory, and sent the data to another computer, a terminal controller, that would, then, and only then, disturb the all important mainframe with the mundane needs or its users.