Lecture 1
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Who is in charge?

 - first program that runs on the system is in charge
 - takes charge of "dangerous" operations

CPU modes
 - supervisor mode: access to all hardware resources
 - user mode: access to limited resources, as defined by code running
    in supervisor mode

Kernel: code that runs in supervisor mode
Processes run in user mode


Process: "running program"

Process making a request of the kernel: system call


APIs