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What is a CPU? CPU meaning…

What is a CPU

You have certainly have stumbled upon the word ‘CPU’ at some time in your life, maybe even several times. Today we are going to look at what it is and define the CPU meaning.

This tiny device has made possible things that a hundred years ago would only have existed only in our imaginations. Since their invention, CPUs have gradually been integrated into more and more devices as humans to automate, ease, or improve production. Its creation has changed the way we live, work, and play.

CPU meaning

CPU is an abbreviation that stands for Central Processing Unit. The CPU is more often colloquially called the Processor or Microprocessor.

It is the core component that you will find in any modern computer. To put it into perspective, think of it as the heart and brains of a computer. Without it, our computers of today would just be heaps of scrap.

Main functions of a CPU

Main Functions of a CPU
Main functions of a CPU

A CPU or microprocessor is the information processing hub of a computer. It receives an instruction either from input devices or memory and then the CPU decodes and executes the received instruction.


It produces a result called an output that is either stored or displayed on the output device. This is the fetch-decode-execute cycle of a CPU.

Although a processor can only execute one instruction at a time, it appears to the user as if it performs multiple tasks at once. This is because it very quickly juggles between different tasks, making it possible to keep several processes running simultaneously without stopping.

What is inside a CPU?

Central Processors are made from a metalloid material called Silicon (Si). Some of the more well-known manufacturers of central processing units that you might have heard of include Intel Corp, AMD Inc., and ARM Ltd.

All modern CPUs generally include the following six components:

1. Control Unit – CU

It can be compared to a choir conductor. This is because his purpose is to decode instructions and directs the performance of all the components so that the whole group works as one unit.

A Control Unit is an electric circuit that fetches and decodes instructions from memory and directs how the Arithmetic and Logic Unit, Memory, and I/O devices should function or respond. It also holds the Program Counter (PC) and Current Instruction (CI) registers.   

2. Arithmetic and Logic Unit – ALU

The ALU is the brain doing all the calculations for the CPU components. It performs arithmetic operations such as addition, subtraction, multiplication, and division, and it can also perform logic operations such as OR, AND, etc.

During logic operations, it compares inputs and makes a judgment, and then gives out the result.

3. Registers


Registers are a small type of memory storage device found inside a CPU. They can quickly store different kinds of data in the forms of 1s and 0s. They are much faster, smaller, and more convenient to use than the main memory or RAM.

Registers can store any data inclusive of instructions, memory addresses, or data output. They vary in their purpose and usage within the CPU as their number depends on the processor’s design and purpose.

Types of Registers more commonly used include the Accumulator, Memory Data Register, Program Counter, Current Instruction Register, etc.

Plainly said, Registers are storage devices occasionally found inside the Control Unit and the ALU. Sometimes they can have additional circuits that perform definite tasks beyond just storage. 

4. Bus

A bus is a fast pathway for data and control signal transfer between two or more components. Three types of Buses are inside processors. They are the Data Bus, Address Bus, and the Control Bus.

The data that each type of bus transmits is overtly proclaimed within its name, for example, a Control Bus transmits control signals from the Control Unit.

5. Clock

It is the heartbeat of a processor that measures how quickly the CPU performs its logic to the clock’s pulse. The clock’s oscillations synchronize the CPU’s components so they can perform in concert with one another.


The speed of a CPU’s operation is often evaluated in terms of clock speed. The CPU Clock oscillates back and forth therefore its speed is measured by the frequency of its cycles per 1 second. It is measured in hertz (Hz).

6. Cache

A cache is a small unit of RAM or main memory now commonly found inside the CPU. It temporarily holds data that the processor often uses and it is much closer to the processor than the RAM.

This enables faster processing as the delays, caused by data retrieval from main memory, are reduced.

What is inside a cpu
What is inside a CPU

CPUs nowadays often have multiple cores. What this means is that the CPU now virtually has more independent processors on a single chip.

Meaning that these cores can execute different instructions simultaneously, increasing the efficiency of the CPU. More CPU cores are better for performance

CPU Architecture

CPUs architecture is divided into two main types, which are RISC architecture and CISC architecture.

RISC Architecture

RISC stands for Reduced Instruction Set Computer. The principle behind RISC is to build a faster central processor by embedding it with fewer instructions or abilities.

This simplifies the CPU instruction set so that more instructions are in a cycle. RISC architecture gains higher instruction to cycle ratio by opting for longer programs and more memory usage.

An example of a RISC processor is the ARM chip made by ARM Ltd in the UK.

CISC Architecture

CISC stands for Complex Instruction Set Computer. The philosophy driving it was to build a processor that is embedded with more default instructions so that instructions written in assembly language would be much shorter and concise.

The drawback however is that the processor would need more cycles to carry out each seemingly simple instruction.

An example of this processor is the Intel processors by Intel Corp.

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