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Chip Architecture is a description of the inner structure of the chip, its buses, its memory and its special function registers.

All the chip internals are connected via shared bus wires.
This greatly simplifies the wiring of the chip.

• Data is READ into the processor using the DATA BUS.
• Date is WRITTEN out of the processor to other locations using the DATA BUS.
• The data origin or destination is determined by the ADDRESS on the ADDRESS BUS.
• Every location within the microcontroller has its own unique ADDRESS so there is never confusion.
• A control bus R/W line informs locations such as the memory
  or the ports whether data is to be READ or WRITTEN.
• All the internal chip operations are synchronised to the control bus CLOCK line.
• The chip uses the HARVARD architecture.
  • An extra PROGRAM or INSTRUCTION BUS
    allows instructions and data to be FETCHED at the same time.
  • This speeds up the chip greatly compared with Von Neumann
    chips without the extra bus.
  • With Von Neumann chips the instructions and data have to be
    fetched in separate steps.