Purpose of CPU and Components (The CPU has three main parts (The…
Purpose of CPU and Components
What is the CPU?
Stands for Central Processing Unit
The CPU contains various registers which temporarily hold tiny bits of data needed by the CPU. They are super-quick to read/write to, much quicker than any other form of memory.
What does the CPU do?
It process all of the data and instructions that make the system work
Factors affecting the CPU
The processing power of a CPU is dependant on many different factors.
Number of cores
What is the CPU architecture?
It describes the main components of the CPU
How they interact with each other
How they interact with other parts of the computer system,
Von Neumann and Harvard are the two main types
The CPU has three main parts
The Control Unit (CU)
Is in overall control of the CPU
Its main job is to execute program instructions by following the FDE (Fetch-Decode-Execute) Cycle
Controls the flow of data inside the CPU (to registers, ALU, cache) and outside the CPU (to main memory and input/output devices)
The Arithmetic Logic Unit (ALU)
The ALU does all the calculations
It completes simple addition and subtraction, compares the size of numbers and can do multiplications and divisions using repeated addition and subtraction.
It performs logical opreations such as AND, OR and NOT and binary shifts
It contains the accumulator register
Very fast memory in the CPU
It's slower than registers but faster than RAM
Stores regularly used data so that the CPU can access it quickly the next time it's needed. When the CPU requests data, it checks the cache first to see if the data is there. If it is not there, it will check RAM.
Caches have a very low capacity and are expensive compared to RAM and secondary storage.
There are different levels of cache memory - L1, L2 and L3. L1 is the quickets but has the lowest capacity. L2 is slower than L1 but can hold more. L3 is the slowest but has the largest capacity.