CPU

Josh:
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I had my first experience with computer hardware when I was 8 years old.

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My dad had brought home an old computer from work that wasn't being used anymore.

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We took it apart, dove inside the case, made sure to avoid touching any capacitors, and

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just looked around.

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We took out the floppy drive, the motherboard,

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sticks of RAM, and the hard drive. We even took the case of the hard drive apart

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so we could look at the shiny platters inside. To this day, that's probably one of my favorite

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pieces of computer hardware. There's something mesmerizing about those perfectly reflective

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platters. And the second you touch them, your fingerprints are all over them. Fun fact, there

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are some powerful rare earth magnets in there that you can take out and repurpose. Just be careful

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you don't pinch your fingers between them. So that was the first time I ever took apart a computer,

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but building one, that happened in college. It was my second year, and I wanted a server to run

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virtual machines on from my dorm room. My college had a slash 16 network, which means every network

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jack you plugged into had a public IP. You could plug in a computer, and boom, it was accessible

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on the internet. So I specced it out and placed my Newegg order. This was before Newegg was acquired

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by a Chinese company. Then for the next few weeks, as parts came in, I would hike up the hill to the

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mail room, pick up each package, and make the one mile walk back to my dorm room. A mile in both

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directions with each individual component really makes you understand just how many different parts

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you need for a computer. Once all the parts came in, I got it assembled and up and running.

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So in this season, I want to cover each main component of a computer. We all use them every

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day, but do we really understand them? The component that does everything you ask it,

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on this episode of In The Shell. The wrong thing to do is just go out and buy a computer

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and then learn about it. You'll learn, but you'll learn a lot of things that maybe you didn't want

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to learn. A computer that you buy today will likely be obsolete six months from now, and there's not a

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dang thing that you can do about it. My name is Josh, and I'm able to keep this podcast independent

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and advertisement-free because of support from listeners like you. If you are finding value in

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what I'm doing here, consider becoming a paid supporter at members.sideofburritos.com. And as

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a thank you, members get early access to new videos, ad-free versions of everything, bonus content,

02:41
and access to a live monthly Q&A. Thanks for considering. Now let's get back to the show.

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At its core, pun intended, the CPU is a processor. It processes instructions. When your computer runs

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a program, or even just boots up, the CPU fetches instructions from memory, decodes them, and executes

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them one after another at lightning speed. This cycle of fetch, decode, execute repeats billions of

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times per second, synchronized by the CPU's internal clock. It also has a small set of specialized tools

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to help get its job done. One tool is the Arithmetic Logic Unit, ALU, which handles basic math and logical

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comparisons. Another is the Control Unit, which manages the flow of data, telling memory and input

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and output devices where to send or receive information. The CPU also uses tiny storage areas

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called registers to keep data it's actively working on. Modern CPUs often include multiple processing

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units called cores on one chip. A quad-core CPU has four cores that can work on tasks in parallel,

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allowing the CPU to handle multiple tasks at the same time more efficiently. Despite all these

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advancements, the CPU's fundamental job remains the same, to execute instructions and process data.

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But how does this tiny chip actually switch and calculate so incredibly fast? The transistor.

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A transistor is essentially a microscopic electrical switch. It can turn

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on or off to either allow electrical current to flow or to block it. This on-off behavior

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is exactly what we need to represent the ones and zeros of binary code, the language of computers.

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Each transistor can be in an on state, allowing current representing a one,

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or an off state, blocking current representing a zero. By arranging billions of transistors

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into complex circuits, engineers create logic gates and high-level components that perform all

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the calculations and decision making inside the CPU. For example, combinations of transistors form

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logic gates like AND, OR, and NOT, which in turn combine to implement everything from addition

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and subtraction to multimedia processing. It's incredible to realize that even the most advanced

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computation,

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ultimately boil down to transistors switching on and off. Historically, transistors replaced

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their larger predecessors, vacuum tubes, in the 1950s and 60s. Early computers like the 1940s

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ENIAC used around 18,000 vacuum tubes as switches, and those tubes ran hot and burnt out frequently.

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Transistors were first demonstrated in 1947 at Bell Labs. They were tiny, used far less power,

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ran cooler, and were more reliable. Over the next decade, engineers dramatically improved

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transistor designs. By the mid-1960s, a new manufacturing approach, the planar process,

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made it possible to build many transistors on a single slice of silicon. This led to the first

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integrated circuits and eventually...

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the first microprocessors in the early 1970s. For perspective, Intel's first CPU, the 4004

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in 1971, had about 2,300 transistors, compared to modern CPUs that can house tens of billions

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of transistors on one chip. This rapid growth in transistor counts followed a trend known as

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Moore's Law, the observation that roughly every two years, the number of transistors on a chip

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doubles, which I talked about more in Season 2, Episode 2 on Gordon Moore. When you hear that a

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CPU runs at 3GHz, what that actually means is that its internal clock ticks 3 billion times per second.

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Each tick is an opportunity for the CPU to move one tiny step forward in the fetch-decode-execute cycle.

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One other important aspect of CPUs is their architecture.

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CPU architecture means the basic set of machine instructions a CPU understands to carry out fundamental operations, things like arithmetic, logic, and moving data around.

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Over the years, different families of CPUs have developed their own languages.

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The most common architectures you'll hear about today are x86, x86-64, which is x86's 64-bit extension, and ARM.

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Modern Intel and AMD desktop CPUs use the x86-64 architecture, which is basically a 64-bit evolution of the older 32-bit x86 standard.

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The jump to x86-64 around the early 2000s was a big deal because it expanded the CPU's capability.

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Older 32-bit x86 chips could only directly use about 4GB of RAM, whereas 64-bit CPUs can address

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vastly more memory, theoretically up to 16 exabytes. Another reason CPU architecture is a big deal

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is the difference in performance and efficiency. x86 and x86-64 chips, the kind in most desktops

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and laptops. They have complex instruction sets, often called CISC, spelled C-I-S-C, which include

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many built-in operations. These CPUs tend to be very powerful and capable of handling heavy workloads

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like video editing, gaming, and software development, but they also use more electricity

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and run hotter as a trade-off. On the other hand, ARM CPUs use a reduced

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instruction set called RISC, spelled R-I-S-C, which is focused on efficiency.

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.

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.

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.

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ARM chips are designed to do more with less. They draw far less power and run cooler,

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which is why they dominate in smartphones, tablets, and other battery-powered devices

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where energy efficiency is crucial. An ARM-based phone can run all day on a small battery.

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Historically, the trade-off was that ARM's CPUs weren't as powerful as their x86 counterparts.

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They handled everyday tasks just fine, but weren't geared for the really demanding stuff.

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However, that line is blurring today. A great example is Apple's M1 chip and its successors

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used in newer Macs. It's an ARM-based CPU that proved ARM chips can be both extremely powerful

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and power-efficient.

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In some cases, Apple's ARM CPUs are on par with or even outperformed traditional PC x86 chips while still running cool.

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And look at how the CPU actually fits into a PC when you are building one.

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Physically, a CPU is a small squarish chip that needs to be installed onto the motherboard.

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The motherboard is something we'll be covering in detail in a future episode.

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The motherboard has a special CPU socket, a slot that is designed to hold the CPU, and connect it to the rest of the system.

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Every motherboard model supports only a particular type of socket, and a CPU will only work if it matches that socket on the motherboard.

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This is why, if you pick an AMD Ryzen CPU,

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You need a motherboard with the correct AMD socket for that chip.

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Once the CPU is seated in the motherboard, the next crucial step is keeping it cool.

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As powerful as these chips are, they generate a lot of heat.

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Without proper cooling, a CPU would overheat and shut down, or throttle itself dramatically to avoid damage.

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So in your PC build, after the CPU is in the socket, you'll attach a CPU cooler on top of it.

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This might be an air cooler, a metal heatsink with a fan, or a liquid cooler, but either way it serves the same purpose, to carry heat away from the CPU.

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Thermal paste is applied between the CPU and the cooler.

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It's a tiny dab of gray stuff that ensures there are no air gaps and maximizes heat transfer between the CPU's surface and the cooler's surface.

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base. When done correctly, this cooling setup keeps the CPU at a happy operating temperature

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even under load. As I was going through my script for this episode, there was one question I kept

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asking myself that I really wanted to know, and that's why are these tiny transistors made of

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silicon? Silicon is one of the most abundant elements on earth. Common sand is largely silicon

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dioxide, which means it's cheap and widely available. But more importantly, silicon is a

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semiconductor, meaning it can act as an electrical conductor or an insulator under different conditions.

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In pure form, silicon doesn't conduct electricity well. However, by doping it, introducing tiny

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amounts of other elements, like phosphorus or boron, we can tweak its electrical properties.

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Doped silicon can carry current in a controlled way, creating regions that either have excess electrons, N-type, or excess holes, P-type.

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Put an N-type or P-type silicon together, and you get a transistor that can switch on or off at your command.

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Additionally, silicon is friendly to manufacturing.

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It can be refined into extremely pure, single crystals, and then sliced into thin wafers you might have seen in photos of chip factories.

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Those wafers are the platform on which billions of transistors are fabricated, using processes like photolithography.

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The abundance of silicon means we can produce these wafers in huge quantities relatively cheaply.

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And the material stability and reliability mean the resulting chips can run for years without degrading.

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It really is amazing when you stop to think about it.

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A CPU is this small piece of material that sits quietly inside your computer, yet it does so much.

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That old machine I took apart with my dad felt so powerful,

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yet today's CPUs run thousands of times faster and pack far more complexity.

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In the Shell is written, researched, and recorded by me,

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the ARM-based podcaster,

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if you are listening in an app that lets you rate shows,

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please take a minute to rate this one.

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I would truly appreciate it.

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I always heard that if you're hiking in the woods, bring a piece of fiber optic cable with you.

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If you get lost, you can bury it,

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and 15 minutes later, five backhoes will be there to dig it up.

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That's it. Take care, and I'll see you next time.