Three Box Model

The Three Box model has three components to it - Processor
                                                                          - Main Memory
                                                                          - Inputs & Outputs (I/O)

It also has a Bus which combines these components.

Processor - The brain of the system.
                - Responsible for executing programs
                - Contains a microprocessor, which can contain up to 1 billion transistors

Main Memory - Also known as the Immediate Access Memory
                      - Used to store program instructions and data
                      - Random Access Memory - Loses its data when Computer is turned off
                      - Read Only Memory - Keeps it's data (non-volatile)
                      - ROM is used to store programs which boot the computer.

Inputs & Outputs (I/O) - Everything outside the computer is a peripheral.
                                    - I/O controllers allows the CPU to communicate with them

Bus - Can be called System Bus or External Bus
       - Connects the Three Boxes together
       - Three Types - Data - Bidirectional (Two Way)
                                         - Consists of 32 wires
                                         - Used to transport Data
                              - Address - One Directional
                                              - Consists 32 wires
                                              - Used to address Memory and I/O locations
                              - Control - Bidirectional (Two Way)
                                             - Consists of 8 wires
                                             - Used to transport control signals between the three components