Role of OS

1. System Resource Manager
   • System Resource = Computer H/W
     • CPU, Memory (DRAM, RAM), I/O devices (keyboard, mouse, network, monitor), storage (SSD, HDD)
   • H/W cannot do anything by itself.
     • CPU cannot decide how much to use
     • Memory cannot decide which address and how much should be assigned for each program
     • Keyboard, mouse cannot indicate itself
2. Support user - computer communication

1. Control and manage computer H/W and Application program
   • Process management
   • Main memory management
   • File management
   • Disk management
   • I/O management
   • Networking
   • Security

Application program

• Program = S/W = OS + Application (App)
• OS manages Apps
  • Execution
  • Permission
  • User (login)
• Why OS need to manage apps? -> Apps can be made by anyone
  • Abnormality may occur
    • Inf loop
    • Program down
    • Unwanted file deletion (managing permisison / user)
    • Using all resources by app itself

Goal of OS: To support App to work efficiently and appropriately by assiging resource efficiently

Where is OS?

• Installed in storage(HDD/SSD)
• OS goes to memory when it boots up
• von Neumann Architecture