External memory, the data bus and the address bus

Introduction

Using buses to read from and write to external memory

Buses facilitate communication between the CPU (including registers) and memory.

bus takes read (just address) write (address and data)

things can read, rw or write on bus. devices on bus can monitor address outputs of cpu. if address corresponds to device can take actions.

Address bus

Address bus connects to part of memory. setting the address bus to x will allow accessing ram at x.

Data bus

Data bus reads or writes to memory at location of address bus.

eg if loading byte of ram at position \(\#FF00\) to accumulator, address bus is \(\#FF00\).