Interrupt

✅ Interrupt

signal emmited from hardware or software when process or event needs immediate attention
if an error occurs during running a program
stop the program
and alert CPU for immediate attention
allow processor to act quickly

• Interrupt Detection:
  • device raises interrupt at process i
• Interrupt Acknowledgment:
  • CPU sends device acknowledgement sign
  • device stops sending interrupt request signal
• Interrupt Handling
  • processor first completes execution of process i
  • address of interrupted instruction move to temporary location
  • processor handles interrupt
• Context Saving, Transfer Control
  • processor loads Program Counter with the address of first instructino of the ISR
• Interrupt Servicing
  • after handling interrupt, processor can continue with process i+1

✅ Types of Interrupt

1. Software Interrupts

   interrupt produced by software
   also called Trap
   

• command, data w error
• divide by 0, overflow, exceptions

1. Hardware Interrupts

occurs bc of external cause

• i/o device, timing device, power

✅ Managing Multiple Devices

when more than one device raises interrupt
additional info is needed to decide which device to be considered first

✔️ Polling

• first devide encountered with the IRQ bit set has priority
• easy to implement
• lot of tame is wasted by interrogating the IRQ bit of all devices

✔️ Vectored Interrupts

• device requesting interrupt
• and identifying directly by sending special code to processor over the bus

✔️ Interrupt Nesting

• device is organized in a priority structure

💡 Reference

https://www.geeksforgeeks.org/interrupts/