Microprocessors

The Journey Inside℠, an Intel® Education Program.

Lesson 1: The Robotic Arm

For you, reaching out and picking up an object requires little thought. But what if you wanted to use a robot to pick something up? Robots are being used in many different industries today—from factories and warehouses to hospitals and shopping malls—to complete repetitive tasks, work in environments that are unsafe for people, and even to make experiences more fun.

But unlike us, robots need very precise instructions on how to do something and in what order. Programming a robot to make a peanut butter and jelly sandwich, for example, could take hundreds of precise instructions. That’s why robotic devices used in factories are designed and programmed to perform just a few tasks over and over again. All of the instructions robots need are stored on a microprocessor.

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Lesson 2: Fetch, Decode, and Execute

Whether a computer is used to play a game, write a report, or search for something on the web, the microprocessor in a computer processes data using the same three steps over and over again. It does these three steps at incredible speeds of billions of times per second:

  1. Fetch: The microprocessor gets a software instruction from the memory telling it what to do with the data.
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  2. Decode: The microprocessor determines what the instruction means.
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  3. Execute: The microprocessor performs the instruction.
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Lesson 3: The Best Things Come in Small Packages

Pluck a hair from your head. (Really.) Now look at it. It isn’t very thick, is it? Well, to a microprocessor manufacturer, that hair looks like a telephone pole. That’s because a human hair is about 2,000 times wider than a transistor on a microprocessor. Wires between transistors are even thinner. They’re more than 8,000 times thinner than a human hair.

See a human hair up close.

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How wide is a human hair? A human hair is approximately 80 to 100 microns in diameter. In comparison, a transistor is just 0.065 microns wide.

What’s a micron? It’s a very small metric measurement. You’re probably familiar with centimeter marks on a ruler. (If not, look for them the next time you have a ruler. At one end of the ruler, you should also see a small CM label.) A micron is .0001 of a centimeter. That’s 10,000 times smaller!

A microprocessor transistor then is 0.0000065 centimeters wide. (Want that in inches? It’s 0.00000255 of an inch.)

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Journey to the Center of a Microprocessor

It is impossible to see the incredibly small transistors and circuits in a microprocessor with your eyes, but with a microscope you can.

Use the different magnification powers of this virtual microscope to see the inner workings of a microprocessor. At the highest magnifications, you will see actual circuit paths.

Microscopic Dust

A lot of dust is so small we cannot even see it. But with a microscope, you can. Use the different magnification powers of this virtual microscope to see how big a microscopic speck of dust can be compared to circuits in a microprocessor. Since a single speck of dust can ruin a microprocessor, you can see how important it is to manufacture microprocessors in virtually dust-free facilities.

To protect chips from dust during the manufacturing process, they are made in clean rooms, which can be 10,000 times cleaner than a hospital operating room.

Lesson 4: How Do They Make Chips So Small?

Because a microprocessor is manufactured, it has to first be designed. This is no easy task. It takes a team of up to 600 engineers. The engineers face a task equivalent to trying to design a small city from the ground up. How much area of the chip should be set aside for temporarily storing information? How much area should be set aside for maintaining instructions currently being used? How much area should be dedicated to accepting information?

Once the areas of the chip have been mapped out by purpose, the circuitry has to be designed down to the individual transistor. With over 500 million of them in modern microprocessors, that’s a lot to keep track of. It’s like creating a city by planning every room in every home and building before you even pick up a brick.

Lesson 5: Recipe for a Microprocessor

While the process of designing and manufacturing a microprocessor is extremely complex, the components are rather simple. In the most elemental terms, microprocessors are composed of silicon, quartz, metals, chemicals, and water.

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Lesson 6: Building Skyscrapers on a Wafer

Ever hold a 20-story building in the palm of your hand? That’s what it’s like holding a dime-sized microprocessor with millions of transistors.

You may be surprised to learn that a single microprocessor is like a miniature skyscraper. A skyscraper has many floors and stairways that connect the floors. Similarly, microprocessors are made of many layers with stairway-like circuits between them. Hundreds of these “skyscrapers” can be produced on a silicon wafer at a time.

See a wafer up close

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From start to finish, a microprocessor takes about two months to produce. Fabrication begins with a very thin slice of silicon. Over 300 manufacturing steps later, this silicon wafer holds hundreds of microprocessors. If you could enlarge the wafer to the size of a swimming pool, the surface would look like a miniature city.

Now think small, and ask yourself this: How are such tiny circuits put in such a small chip? Good question! No mechanical object or pen could lay down such incredibly microscopic wires. Instead, the pathways for the current are created by using solvents to remove channels of material. These microscopic channels are then etched with chemicals and implanted with electrons to make them conduct electricity.

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Explore a Microprocessor

This activity lets you select and view sections of a chip at a fixed magnification. Imagine you are putting a microprocessor on a microscope slide and moving it around the lens.

Once you’ve started the lesson, choose Select. Then, use your pointer to grab and drag the white circle to the part of the chip you want to view. Use the Focus, Intensity, and Zoom controls to perfect your image.

As you examine the processor, think about how different areas of the chip handle various tasks. Can you tell what each particular area of the chip does—fetch, decode, or execute?

Unless you are a chip designer, it would be hard to guess. Today’s advanced microprocessors with their multiple layers and millions of transistors are too complex.

What conclusion can you make? There is incredible processing power for all three tasks in something smaller than your fingernail.

Exploring Chip Layers

Chips may look flat, but they can have as many as 20 layers. Each layer is full of tiny pathways that make up the circuits and transistors of the chip. There are also microscopic connections running between each layer.

This activity lets you move between the several layers of a chip by focusing on various depths. Use the Focus Depth control to change the layer visible through the microscope.