Class notes --02 operating system, the operating system basics
2.1, OS startup
DISK: storage OS
BIOS: Basic I / O processing system
Bootloader: Load OS
POST (Power On Self Test): Looking for graphics and execute BIOS
2.2, OS interact with the equipment and procedures
- System calls, exceptions, interrupts
Three interactive event source:
- Interrupt: Peripherals
- Exception: unexpected application behavior
System call: application requests the operation service
Processing time of three interactive events
- Interrupts: Asynchronous
- Exception: Synchronization
System call: asynchronous or synchronous
Three state response interaction events
- Break: continuous, for user application is transparent
- Exception: Kill or re-execute unexpected application instructions
System call: Wait and sustained
Handling mechanism interrupts and exceptions
Detailed analysis of system calls:
The main program is accessible interface instead of a direct system calls through high-level API
Overhead across operating system boundaries