Interrupt Service Routines

ISRs

ISRs should be as fast as possible ISRs must avoid blocking I/O functions

See page 45 for the structure of an interrupt

Initialization

The following steps need to be taken when initializing a software system that uses interrupts:

1. Disable all interrupts
2. Enable device interface interrupts by setting appropriate device interface registers
3. Set interrupt mask to allow interrupts from device
4. Initialize interrupt vector with address of ISR
5. Enable interrupts as required If interrupts are disabled, steps 2-4 can be done in any order.
   

This is known as global initialization