What Does CPU Stand for?
To start with, let’s clarify what a CPU is, as this will give us a better understanding of exactly how it relates to a microprocessor. CPU stands for central processing unit, which is sometimes written as central processor unit, or often simply the processor.
The CPU or processor is a small but highly important piece of electronic circuitry that operates and controls an entire array of computer hardware. It can essentially be thought of as the brain of your system - be it a desktop or laptop PC, or any other electronic device that requires a CPU to function.
Indeed, thinking of the processor as the brains of the system should help to answer the common question: why does a computer need a CPU?
The CPU is responsible for executing the full array of operations and programmes that a computer can perform. It handles all the device’s core arithmetic, logic, and input and output functions.
Until a CPU is installed, none of the other system components will be able to carry out their roles or communicate with one another. Even when connected to a PSU (power supply), other hardware such as RAM, separate graphics cards and hard drives will effectively be redundant without a CPU to control them.
However, while a CPU is a vital component in a working computer, it is just one small part of the device’s core circuitry. Many other types of circuits and transistors are required to enable full communication between the CPU and the rest of the system.
In the past, these often needed to be housed separately due to limitations in physical space and power distribution. However, modern advances in microtechnology have seen many modern CPU dies shrunk down considerably. As a result, they are now commonly placed directly alongside other key circuits on a single integrated circuit (IC), known as a microprocessor.
What is a Microprocessor, and How Does It Relate to CPUs?
In most of today’s consumer-grade home or office PCs, the CPU is housed alongside other key circuits within a single multi-function silicon chip. The same is true of many other types of electronic smart devices and systems.
This single chip is usually referred to as a microprocessor (or sometimes a logic chip). A microprocessor will also contain numerous other transistors, circuits and components, each designed to handle or facilitate various key functions within the wider system.
For this reason, a microprocessor is a type of Integrated Circuit (IC). As most modern CPUs are now built and housed on single-chip ICs in this way, the terms CPU and microprocessor have become somewhat interchangeable. Despite this, it is worth noting that while most CPUs are now supplied as microprocessors, not all microprocessors are CPUs.
Microprocessor ICs are also used to house other types of circuitry, such as discrete GPUs (graphics processing units). Many modern computers, for example, use dedicated graphics cards to handle render and display output externally from the central processor. These discrete graphics cards will also feature microprocessor ICs, but with a GPU rather than a CPU at their core.
In short, a microprocessor may or may not feature a CPU, alongside other transistors and circuits for handling multiple system operations. Where a CPU is present, the microprocessor provides pathways for it to communicate directly with the rest of the computer hardware.
A microprocessor with a CPU on board is often called a SOC, or system-on-chip. These often feature various other key components like onboard memory or peripheral interfaces and can execute functions and programs across a device’s entire system. Due to this multi-function capability, microprocessors are often suitable for standalone use in smaller or less complex electronic devices, as well as in many modern computers.
It should be noted that microprocessors should not be confused with microcontrollers, which are a stripped-down version of a similar principle. Microcontrollers are much more limited chips, often found in devices programmed to perform a single basic function repeatedly.