Give example of bus and memory transfer

For example, the read operation for transfer of a memory unit M from address register AR to another data register DR can be illustrated as:

Read:  DR ←M [AR]

The  write  operation  transfer contents  of  a  data  register  to  a  memory  word  M selected by address. Assume that input data are in register R1 and address in the AR. The write operation can be stated symbolic as belwo:

Write:  M [AR] ← R1

This cause a transfer of information from R1 into memory word M selected by address in AR.