Input Output (I/O)

The way a machine receives input and gives output.

Polling

Constantly looping an instruction checking if there is an input

Interrupt

Input signals the computer to stop what its doing and read the input.

1. Incoming interrupt suspends instruction stream

2. Look up the vector (function address) of a handler in an interrupt vector table stored within the CPU

3. Perform a jal to handler

   • Save PC in Machine Exception Program Counter (MEPC) register

4. Handler run on current stack and returns on finish