What is a microprocessor? If we want to be precise, it’s any type of miniature electronic device with functionalities enabling it to serve the function of a computer central processing unit (CPU). Microprocessors are the heart of embedded systems; therefore, we dedicate this article to discussing them in detail. Does this topic spark your interest? Then we invite you to read on!

What Is a Microprocessor? Definition.

The most common definition of a microprocessor is, that it’s a CPU on a single chip (integrated circuit). However, saying this is not enough.

You might, for instance, come across microprocessors with more than one IC, though their number should still be scarce anyway. Additionally, to make the definition complete, we should mention that a microprocessor needs to be capable of interpreting and executing instructions as well as performing arithmetic operations.

Another element that is not mentioned in most definitions, though is often (though not always) crucial in practice, is the architecture, or rather the architectures. Microprocessors may be based on different ISAs. These architectures may be quite similar or significantly different as, for instance, RISC and CISC, so it’s good to be aware of their ins and outs.

What Are the Key Components of a Microprocessor?

While in itself a microprocessor is a complex piece of hardware, capable of being the base of numerous different devices, we can simplify it and look only at its key components, especially since we can distinguish only four of them:

  • Control unit (CU) – This part is responsible for orchestrating, coordinating and directing the execution of instructions. It picks the instructions up from the memory, understands them, and finally puts the required actions into life.
     
  • Arithmetic logic unit (ALU) – This is the key element of a microprocessor responsible for calculations and logical operations orchestrated by the instructions received from the CU.
     
  • Registers – Whenever your microprocessor needs to store and retrieve data quickly, it will do so in the registers. They offer limited storage space, which is perfect for information that the CPU needs right away.
     
  • Cache memory – This is the access point for the microprocessor’s most frequent instructions and data – it doesn’t store as much information as main memory, but using cache is faster, so it accelerates the whole system.

Microprocessors and Architecture

The architecture of a microprocessor is often crucial, as it might define, for instance, what devices does a particular line of processors work best for. Here you’ve basically got two options: the older CISC and the Younger RISC.

You can learn more about them in our article What Is RISC and CISC Architecture & Their Differences, so we won’t be devoting a lot of attention to these two architectures here, though here’s a brief introduction if you prefer this information in a nutshell:

  • CISC – Older, slower, more complex – perfect for systems working on videos, graphics, vast amounts of complicated data or science computers.
     
  • RISC – Based on simple, mostly one-word instructions, the processors in this architecture are usually smaller, more energy-efficient, and quicker, which makes it perfect for mobile devices and embedded systems.

Going Further

The main division between CISC and RISC isn’t the only one – the architecture can often be divided further, as in the case of RISC-V vs. ARM – two ISAs based on RISC. However, when it comes to those smaller distinctions, they rarely matter when you design your own system or product, as neither of them has a clear-cut advantage over the others, and there are more important factors to consider than those ISO-restricted ones.

Microprocessor vs. Microcontroller

One of the most common mistakes regarding microprocessors is that their name is used interchangeably with a microcontroller on a regular basis. However, these two are not the same (after all, hence the difference in name). So, what’s the difference?

In general, a microcontroller contains memory, CPU, and programmable I/O all in one circuit, while a microprocessor contains only the CPU. However, there is a bit more to it, and there are some differences that emerge as a direct consequence of this distinction – you can learn more about them in our article on microprocessor vs. microcontroller.

Microprocessors in Embedded Systems

Naturally, due to their size and capabilities, microprocessors have been widely used in embedded systems. After all, for embedded devices, the dimensions, power efficiency and speed are more important than complex functionality. Though, we must underline that microcontrollers are also used for this purpose.

As mentioned before, you will most likely see RISC processors in embedded systems. But, when it comes to more detailed choices like a particular ISA, practically every option becomes viable. Though not every processor will be best suited for every embedded system, so it might be worth considering what you are actually creating and choosing the best core for your device’s purpose.

The Takeaway

Understanding what a microprocessor is, no matter whether it’s in a computer or an embedded device, is crucial. After all, selecting the right “heart” for your embedded system may define its success and high functionality, while picking the wrong one can effectively hinder your product’s development. Bear in mind that you should consider integration and compatibility with new features and old technologies when making your choice – you don’t want to build a device that will be incompatible with the old tech in your client's facilities, right?

We also recommend reading: What Is an Embedded System and How Does It Affect Our Daily Life?