The CPU In Detail

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If you read our breakdown of how a computer works, you’d notice that the Central Processing Unit (CPU) is the brains of the entire operation. Like any other computer component, the CPU is made up of numerous parts that help not only your computer run, but also try to speed things up.

In this lesson, we will go over each key part of the CPU and explain how they help make modern computing possible!

The CPU “Chip”

If you ever tried to build your own computer, or you’ve had the chance to take a peak inside, you may have seen the CPU. If you haven’t, the CPU is a small square in the middle of the board, with the logo of the manufacturer on the top (Intel or AMD likely). This is the CPU “chip”. The CPU sits inside the CPU socket, which connects the CPU to the computer’s motherboard, allowing for the chip to receive electricity, and communicate with all other components.

If you were to turn over the CPU to the other side, you will see some small capacitors and resistors in the middle of the chip. These handle the electrical pulses that create the clock rates for the CPU (an explanation of clock rates can be found in the “How Computers Work” article).

Around the edges, you’ll see plenty of little golden “squares”. In older CPU, these squares would be pins, which would connect to the motherboard so the CPU can draw power to run. In modern motherboards, the pins are in the CPU socket, where the CPU is placed. These pins contact the squares to provide the necessary power to the CPU.

While there isn’t much to see with the naked eye, the CPU contains far more parts that enables it to become the brain of the computer. Let’s look into more detail of what these parts are, and how they help create the modern computing experience.

CPU Cores

When reading information about a specific CPU, you’ll notice that there are details regarding how many “cores” a CPU has. Each “core” is actually a CPU itself! This means that a CPU chip with multiple cores can run multiple tasks at the same time, which in turn speeds up your computer. You can see how many cores your CPU has on a Windows machine by bringing up your task manager. To bring up the task manager, follow these steps:

  1. On your keyboard, press the Ctrl, Alt, and Delete button at the same time. You will be directed to a screen that shows the following options:
    1. Lock
    1. Switch User
    1. Sign Out
    1. Task Manager
  2. Click the “Task Manager” option. If this is the first time you are running the task manager, you will have a small screen like the image below. In order to see the details about your CPU, click the little arrow in the circle on the bottom left labeled “More Details”.
  3. After expanding the task manager screen, you will see multiple tabs available on the top, as seen below. Click on the “Performance” tab. The CPU details will be at the top of the list, so you won’t have to worry about finding it.

On the bottom of the chart, you’ll see all the available information about your CPU, including the number of cores the CPU chip has.

What are these “logical processors”?

Like everything else in technology, CPUs have become smarter and a lot more advanced. CPU manufacturers have found a way to “trick” your computer’s operating system to run two instructions for each core at a time. This is known as “hyperthreading”. So, if your CPU has 4 cores, you will see that it has 8 logical processors, meaning 8 instructions can run through the CPU simultaneously.

Show me the cache

As we discussed in our overview on how a computer works, when you begin running a program, instructions required for the program to run are stored in RAM. As the program continues to run, there may be some instructions that happen repeatedly and data that is consistently used. To help speed things along, the CPU uses a special type of memory known as cache (pronounced cash) memory.

In modern CPUs, there is a three-tier level of cache memory, L1-L3. L1 cache is the fastest, but smallest, level of cache. The L1 cache is usually under a half a megabyte in size, but powerful CPUs are now capable of coming close to 1 megabyte. The L1 cache is used to hold both the instructions and data for the operation that is currently running.

L2 cache is the next level of cache memory. While it’s slower the L1, it makes up for the slower speeds by having more space available. The size of L2 varies from as little as 256 KB to as much as 8MB. While L1 works with data and instructions of the current operation, L2 holds onto the data and instructions for what the CPU will access next.

L3 cache is the final level in the cache memory hierarchy. While L3 cache is the slowest of all cache memory, it is the largest in size. The size can range from 4 MB all the way up towards 50 MBs. While L1 and L2 cache reside on each individual core of the CPU, L3 cache is shared between all L1 and L2 cache memory. Basically, L3 acts as another storage location for frequently used data and instructions so bottlenecks don’t happen. L3 cache will hand off data and instructions to L2 cache, which will then move it up to L1 cache.

Turbo Charged!

If you look at the information provided by the CPU manufacturer, you may notice something called “Turbo Boost” or “Turbo Core” on the packaging/specifications page. All CPUs have a base clock speed that are measured by the manufacturer (more information on clock speed can be found in the “How a Computer Works” article). With the “turbo” capability, the CPU will be able to increase the clock speed where needed for processes to run faster, like playing games that require plenty of power. CPUs with turbo technology will drop back down the normal clock speeds when certain conditions are met, such as a lower workload or the CPU temperature is high.

Conclusion

CPUs are constantly evolving as technology continues to progress. What used to take hours for a computer to process can be done in minutes or even instantly. With the ability to add multiple cores to one chip, work can get done faster and more efficiently. And as clock speeds continue to grow, what seemed impossible a few years ago is now no sweat to a computer.

Sources

Hoffman, Chris. CPU Basics: Multiple CPUs, Cores, and Hyper-Threading Explained. How-To Geek, 12 Oct. 2018, http://www.howtogeek.com/194756/cpu-basics-multiple-cpus-cores-and-hyper-threading-explained/.

Rouse, Margaret, and Reza Nazari. “What Is Hyper-Threading? – Definition from WhatIs.com.” WhatIs.com, Oct. 2006, whatis.techtarget.com/definition/Hyper-Threading.

Rouse, Margaret, et al. “What Is Cache Memory? – Definition from WhatIs.com.” SearchStorage, searchstorage.techtarget.com/definition/cache-memory.

Volvoikar, Palash. “How Does CPU Cache Work and What Are L1, L2, and L3?” MakeUseOf, 31 Dec. 2018, http://www.makeuseof.com/tag/what-is-cpu-cache/.

“What Is Central Processing Unit Cache (CPU Cache)? – Definition from Techopedia.” Techopedia.com, http://www.techopedia.com/definition/6659/central-processing-unit-cache-cpu-cache.

Wilson, Tracy V., and Ryan Johnson. “How Motherboards Work.” HowStuffWorks, HowStuffWorks, 20 July 2005, computer.howstuffworks.com/motherboard2.htm.

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