Operating Systems

Operating System: a layer of software that abstracts the hardware by providing programs with a better, simpler, cleaner abstractions to work with

Kernel mode (aka supervisor mode) vs. user mode

Multiplexing is the sharing of resources:

• Time multiplexing: managing when resources can be used
• Space multiplexing: managing how space is shared between resources

Shell: Takes in user input to run programs and commands

OS Structure #

Monolithic vs Microkernel Virtual machines

1. Processes
2. Threads
3. IPC
4. Scheduling
5. Memory
6. File systems
7. IO
8. Virtualization
9. System calls