Computer hardware can actually be more easily divided into CPU + memory +io devices. The three of them are through a bus to exchange data, and you know in the three CPU speed of the fastest, memory second, IO device third, to make the three coordination of communication requires a certain control.
2. our CPU has its own local bus, the same memory, the local bus through the motherboard of the South Bridge chip link together to communicate. North Bridge generally connected to high-speed bus (connected to memory), South Bridge is generally connected to low-speed bus (keyboard mouse, hard disk). These bridges roll up the bus to connect to the CPU.
3. Each IO device is an IO controller (controllers) he is used to convert the computer's instructions into electrical operations, and vice versa. There is also a disconnect controller inside the computer , which is used to tell the CPU that the current interrupt was made by that device, After the CPU receives an interrupt from the IO interrupt period, it goes to the IO port to read the IO information.
Marco Linux Basics-1-Computer hardware review