“Programs = data structures + algorithms” If you have more than one program, they need shared data and access procedures, like the “user” and “the hardware”. W

“Programs = data structures + algorithms” If you have more than one program, they need shared data and access procedures, like the “user” and “the hardware”. Who manages them: The OS? Maybe you want to share a bit more like some common higher level functionality. That becomes part of the OS, de jure (resident kernel) or at least de facto (loadable kernel modules).