The CPU coordinates all computer operations, e.g. arithmetic and logical operations on data.

In order for the CPU to carry these operations, instructions of what to do and the data to be operated on must reside in the computer's main memory.

The CPU operates according to the following sequence:

1. retrieves each instruction in sequence,
2. interprets the instruction to see what should be done,
3. retrieves any data to carry out that operation,
4. performs the actual processing of the data,
5. and stores the results temporarily in the main memory.