Microprocessor and Memory Basics

Reading data from memory

The process of reading data from memory is usually referred to as "loading" data from memory into the processor. All three of the system buses are involved in this process.

    • 1. Set the address (of the memory location) on the address bus.
    • 2. Set the read/write wire of the control bus high (i.e. request a read operation).
    • 3. Set the address valid control wire high.
    • 4. The address valid signal, together with the value on the address bus will activate the chip select wire on the appropriate memory chip.
    • 5. The contents of the memory location will now be placed on the data bus.
    • 6. Read the value from the data bus - usually into a register in the microprocessor.
    • 7. The read/write, address valid and chip select wires can now all be set low.

The read/write wire is usually labelled R / W