OS concepts 2 handling of interrupts
- 1. Operating System Concepts: 2 Handling of Interrupts Prof Neeraj Bhargava Vaibhav Khanna Department of Computer Science School of Engineering and Systems Sciences Maharishi Dayanand Saraswati University Ajmer
- 2. Computer System Organization • Computer-system operation – One or more CPUs, device controllers connect through common bus providing access to shared memory – Concurrent execution of CPUs and devices competing for memory cycles
- 3. Computer-System Operation • I/O devices and the CPU can execute concurrently • Each device controller is in charge of a particular device type • Each device controller has a local buffer • Each device controller type has an operating system device driver to manage it • CPU moves data from/to main memory to/from local buffers • I/O is from the device to local buffer of controller • Device controller informs CPU that it has finished its operation by causing an interrupt
- 4. Common Functions of Interrupts • Interrupt transfers control to the interrupt service routine generally, through the interrupt vector, which contains the addresses of all the service routines • Interrupt architecture must save the address of the interrupted instruction • A trap or exception is a software- generated interrupt caused either by an error or a user request • An operating system is interrupt driven
- 6. Computer Startup • bootstrap program is loaded at power-up or reboot – Typically stored in ROM or EPROM, generally known as firmware – Initializes all aspects of system – Loads operating system kernel and starts execution
- 7. Interrupt Handling • The operating system preserves the state of the CPU by storing registers and the program counter • Determines which type of interrupt has occurred: – polling – vectored interrupt system • Separate segments of code determine what action should be taken for each type of interrupt