Random Access Memory

Here is a simple model:

address +--------+
   bus  | Memory |
---/----|        |
   8    |  256   |
        | bytes  |
  data  |        |
   bus  |        |
---/----|        |
   8    |        |
        |        |
read/   |        |
 write  |        |
--------|        |
        +--------+

Here, the memory is internally divided into 256 bytes, each of which is a register holding 8 bits. Each of these registers can be accessed individually by placing the address of the byte upon the address bus. Then, depending upon the assertion level of the "read/write" line, the accessed byte will either have its data placed on the data bus, or will have the data on the data bus stored into it.

See also Read Only Memory, Flip-Flop, bus.