Operating Systems

Operating Systems

1. Interrupts

   • Tasks of high importance can't wait for allocated CPU time. Interrupts immediately pause execution of all processes to execute a new one
     • The OS will back up existing processes so they can be resumed after the interrupt is finished
   • They can be triggered by hardware or software
     • Hardware Interrupts include moving a mouse ot pressing a key
     • Software interrupts are triggered by apps and include warning boxes

2. RAM

   • Memory is split into pages so there is enough for each program.
     • Prevents programs from looking at data from other programs

3. Backing Stores

   • Storage devices that keep backups of important files

4. Peripherals

   • Devices that connect to a computer
     • printers, game controllers, etc
   • Drivers are used to communicate to them

5. Security

   • Verifies usernames and passwords, and ensures programs do not damage system files

6. CPU

   • Multitasking
     • The OS keeps tasks separate and manages the accumulator and memory locations
     • The processor appears to be running multiple tasks simultaneously but the processor is running commands separately, filling in the time when waiting for other components.

7. GUI vs CUI

   • GUI
     • Easy to learn, lots of information shown at once
     • Uses a lot of system resources, complexity means more could go wrong
   • CUI
     • Few system resources used, easy to automate as commands can be stored in files
     • Hard to learn, difficult to compare outputs of different programs