The processor handles all instructions and ensures hardware and software function properly. It can execute millions of instructions per second and must fetch, decode, and execute instructions from RAM while performing arithmetic calculations and logical operations. The arithmetic logic unit handles all calculations and decisions by adding, subtracting, comparing, and using logical operators. Registers provide temporary storage, and the control unit manages data flow with a clock, reading and writing memory, and responding to interrupts.

1. The Processor

2. Central Processing Unit
(Processor)
The processor is the part of the computer
system that handles the instructions used to
ensure that hardware and software respond as
expected.
Processors can handle millions of instructions
per second.
Processors must be able to:
• fetch, decode and execute instructions
from RAM
• perform arithmetic calculations
• perform logical operations
• control read, write, clock, interrupt and
reset lines

3. Arithmetic and Logic Unit (ALU)
All calculations and logical decisions are
handled by the ALU.
Processing real numbers would be an
example of an action performed by the ALU.
• carries out calculations e.g. adding /
subtracting numbers
• compares numbers e.g. 5 > 4
• performs logical operations using AND /
OR / NOT

4. Registers
• temporary storage locations within
the processor
• stores addresses, data or
instructions

5. Control Unit
• manages the flow of data around the computer
• uses a clock to synchronise events
• has a read line which tells memory that data is
being read to the processor
• has a write line which tells memory that data is
being written from the processor
• has a reset line to reset the contents of the
registers
• has an interrupt line which is used to signal
that there is an event needing attention