I/O Programming

PMIO: Port-Mapped I/O

• Special Instructions

MMIO: Memory-Mapped I/O

• Memory load/store instructions
  • (you can just use lw and sw to interact)

There are four technique for I/O programming:

1. Programming I/O (PIO)
   • With busy-waiting
   • With polling
2. Interrupt
3. Direct Memory Access or a special processor for I/O called I/O processor.
   • CPU can program the hardware.