An
input/output (I/O) unit manages data and instructions entering and
leaving the processor. A control unit manages all activities inside the
processor itself. One or more arithmetic logic units (ALUs) do all
logical comparisons and calculations inside the processor. Registers,
which are small holding areas on the processor chip, work much like RAM
does outside the processor to hold counters, data, instructions, and
addresses that the ALU is currently processing. Internal memory caches
(L1, L2, and possibly L3) hold data and instructions waiting to be
processed by the ALU. Buses inside the processor connect components
within the processor housing.
