CPU Interrupt Hardware

CPU accepts interrupt request:

1. Save PC and Flag register 2. Change mode bit 3. Push ISR’s starting address to PC

ISR { 1. Inhibit INT; 2. Pop CPU registers and save them in PCB; 3. Check which type of INT 4. Check which event occurs/what device requests

INT 5. Perform corresponding interrupt service 6. Set clock timer 7. Clear corresponding INT bits and event register

and in INT register 8. Scheduler () {Select a process from Ready Queue; Context switch;}

CPU

EOI (End of Instruction)

... I ZMC ...

0 000 0

IRQ(Interrupt request)

Input Output Clock Timer

INT

Time slice times out

INT register

Event/device register

…

Flag/Status register