I/O Handling Methods: Channel I/O

4. I/O Processors are small and smart CPU-like devices that control channel paths connected to I/O devices.
   
   They are similar to a smart DMA that can perform complex I/O-related activities, such as calculations and jumps, which means that they can resolve various I/O errors if such happen during an I/O event. This method is called Channel I/O.
   
   The main CPU still needs to dispatch the job to an I/O processor, specifically, by telling where the code that the processor needs to run is located in RAM, but that's it: the CPU isn't involved anymore in any part of an I/O event.
   
   Pros: The essence of the I/O Processor(s) grants independence from the CPU in terms of handling various events, thus freeing the CPU for doing other, more meaningful activities.
   Cons: Building such a complex system with several small CPUs has financial costs (more time, expensive materials, and smarter specialists are needed for constructing this kind of computer.)