What is a central processing unit (CPU)?

What is a CPU?

The central processing unit is the main hardware component of electronic equipment, from a fitness bracelet to a gaming laptop. It provides computing power, performance, processes information, and issues commands necessary for the correct functioning of the device, the operating system as a whole, and its individual applications.

In simple terms, the CPU is the “brain” of electronic equipment. Without this “brain,” all other hardware components will be useless and inoperative, even if we are talking about the most advanced video card models, huge RAM modules, and solid-state drives.

A little history

The history of computers begins in the 20th century, and of course, it is inextricably linked with processors. The first models were based on triggers and valves, which led to huge power consumption with minimal performance. In the 50s, vacuum tube devices appeared, in the 90s - microcircuits supporting data caching functions.

Modern CPUs are electronic components based on transistors. The development of the electronics industry, the development of new production methods - all this allows us to reduce the physical dimensions of transistors, use billions of tiny modules when assembling a processor. The result is increased performance, more complex architecture, the ability to use not 1-2 cores, as 10-15 years ago, but many, 4, 6, 8.

Other characteristics are also developing:

• Energy efficiency. The component consumes less energy, heats up less, while maintaining high computing power.
• Resistance to temperature load. The modules are made on the basis of graphene and other materials that can withstand intense heating, facilitating rapid removal and dissipation of excess thermal energy.
• Data exchange speed and cache capacity growth. A typical example of the technology is 3D NAND.

Functions

The main functions performed by the CPU are as follows:

• Execution of instructions specific to certain commands and applications. Depending on the type of software, information is read and transferred between other hardware components.
• Memory management. The process interacts with both RAM and cache, which ensures fast operation of applications, confident execution of all instructions and functions specific to them.
• Information processing. It is the processor that carries out all the actions, from mathematical to logical, without which effective interaction with information would be impossible.
• Managing the operating system, ensuring effective interaction between peripheral devices connected to the computer and its internal modules.
• Caching. Each processor has a certain amount of cache used for short-term storage of information and instructions. The faster the cache, the larger its volume - the higher the overall system performance.

Working algorithm

The CPU executes instructions sent by programs installed on a smartphone or PC. All calculations are carried out in strict accordance with them, the working cycle is formed by several stages:

• Receiving a command. It is transmitted from RAM.
• Decoding the command.
• Executing the command.

A similar algorithm was first described by John von Neumann, a professor of mathematics from the USA. The description dates back to 1945, however, it is still relevant. Computing power, however, is growing, so that modern devices are capable of implementing a similar cycle millions and even tens of millions of times per second.

Upon completion of the operation, the CPU saves the obtained results in the PC memory, or sends them to another device, be it an external hard drive or video cards. The result of the processor's actions, visible to the user, is the execution of a certain task, be it starting a video, opening a browser, starting to scan or print a document.

In a complex version, the processor's operation scheme is as follows:

• The control unit receives commands scheduled for execution from RAM, where the program is stored. These commands are recorded in the processor's own cache.
• Writing the received information into registers.
• Analyzing information and executing commands.
• Writing the received results into registers. If the instruction is successfully completed, the results are recorded in the buffer memory, from where they are transferred to the RAM to unload the cache and free up computing power, or they are transferred to the lower-level cache, which is typical for executing particularly complex instructions and commands.

Processor structure

The processor consists of several components, each of which performs specific tasks:

• Control unit. Thanks to this component, programs are executed correctly. The CU receives commands from the RAM and deciphers them;
• Arithmetic logic unit. Its task is to execute commands, mathematical, logical operations;
• Registers. The smallest cells that provide temporary storage of information. Thanks to the registers, the CPU does not have to constantly interact with the RAM, which increases performance;
• Cache. The second memory format, characterized by increased capacity compared to registers. The cache stores instructions and information that needs to be accessed regularly.

Classification of Processors

CPUs can be classified by many features. For example, they can be miniature, mobile, designed for use in smartphones, tablet computers and other portable equipment, or oriented towards laptops or desktop computers. The difference between the latter is blurred, however, office laptops often have low-power modules, which increases autonomy and reduces the load on batteries. Desktop PCs require a network connection, so power consumption is not such a significant indicator, the emphasis is on performance.

A separate category is server CPUs. They have to interact with several clients at once, and therefore they require several cores, an increased cache size, are characterized by high performance and support large amounts of RAM.

Processors can also be classified by the specifics of command execution:

• CISC – a device that supports a full command set;
• RISC – the main feature of this type is to increase productivity by simplifying instructions. The number of transistors is reduced, which reduces cost and energy consumption;
• VLIW – the CPU executes commands, pre-combining them into bundles.

Key characteristics

The main indicator when selecting a CPU is its performance, which depends on the following parameters:

• Clock frequency. The higher the frequency, the more operations the device will perform per unit of time. Just a couple of decades ago, the frequency was measured in hundreds of megahertz, and now - in gigahertz. It should be taken into account that along with this characteristic, energy consumption and the amount of heat generated increase. A productive processor will need a large radiator and an effective cooler.
• Number of cores. Multi-core processors can simultaneously perform several tasks at once, which is not available to their single-core counterparts. You should also pay attention to multithreading, the ability of one core to handle multiple command streams at once.
• Cache memory size. Everything is simple here - the larger the cache, the more productive and faster the CPU.
• Technological process. It indicates the dimensions of the transistors used in the processor. The smaller the transistors, the more productive the device, the lower the amount of energy it emits.
• Heat emission. The amount of thermal energy emitted by the CPU is measured in watts. This indicator is especially important for laptops and other portable equipment. The efficiency of the cooling system is severely limited by the size of the case, and laptops have big problems with this. The throughput of the holes and the power of a small fan for proper blowing are not enough, the laptop begins to slow down, throttle, the processor - artificially lower the frequency to prevent overheating. For desktop computers, this is not such a significant indicator, in a large case it is quite possible to install several coolers, or even a water system capable of cooling even a high-performance CPU with huge heat emission.

Selection rules

First of all, you need to consider what the processor will be used for. If you plan to do basic office work in Word and Excel, watch videos, then you don’t need to chase high-performance models, an inexpensive version with 2, maximum 4 cores with average clock frequencies will be enough. Another thing is computer games, graphics processing and other tasks that require huge computing power. In such a situation, it is better not to save.

The second point is the socket. It is necessary that the motherboard allows the very possibility of using a certain CPU. If the socket is incompatible, installation will be impossible.

We must not forget about the manufacturer and positioning. The main market players are AMD and Intel, in whose catalogs you can find both inexpensive series for office tasks and premium gaming ones, distinguished by high clock frequencies, multithreading and other features that increase productivity, eliminate throttling and other unpleasant phenomena that interfere with normal play and work.

It is necessary to take into account that CPUs are developing at an active pace, and the requirements of gaming and work applications are growing by leaps and bounds. When buying a device, it is better to immediately provide a performance reserve of 20-30 percent, so as not to face the need for rapid modernization and additional costs.

Author of the article:

Editor-in-Chief

Danaev Almaz