How do computer chips work

The first microprocessor to make a real splash in the market was the Intel , introduced in and incorporated into the IBM PC which first appeared around If you are familiar with the PC market and its history, you know that the PC market moved from the to the to the to the to the Pentium series to the Core series to the Xeon series.

All of these microprocessors are made by Intel and all of them are improvements on the basic design of the Since , Intel has introduced microprocessors with multiple cores and millions more transistors. But even these microprocessors follow the same general rules as earlier chips. An Intel Core i9 processor can have up to eight cores , each of which can execute any piece of code that ran on the original , only about 6, times faster!

Each core can handle multiple threads of instructions, allowing the computer to manage tasks more efficiently. Intel's product range has widened substantially from the s. In addition, Intel offers the Celeron and Atom processor lines. Celeron is aimed at entry-level computer users, and Atom processors are better for mobile devices and devices that are part of the Internet of Things.

While Intel still has a large portion of the market, it has more than its fair share of competitors. AMD competes with Intel in the PC processor market, but also does big business in graphics processor chips that are popular with PC gamers. Nvidia, famous for its graphics chips, also manufactures CPUs.

In , Apple introduced its M-series chips, which are replacing the Intel chips Apple was using for its Macintosh computers.

Samsung may also be working on its own proprietary processor designs. Many more companies build processors for other electronics uses, like cars and smart home products. The market is getting more and more competitive. A chip is also called an integrated circuit. Generally it is a small, thin piece of silicon onto which the transistors making up the microprocessor have been etched. A chip might be as large as an inch on a side and can contain tens of millions of transistors.

Simpler models might consist of a few thousand transistors etched onto a chip just a few millimeters square. It has become common to see chips in all kinds of devices with multiple cores, each of which is a processor. To understand how a microprocessor works, it is helpful to look inside and learn about the logic used to create one. In the process you can also learn about assembly language — the native language of a microprocessor — and many of the things that engineers can do to boost the speed of a processor.

A microprocessor executes a collection of machine instructions that tell the processor what to do. Based on the instructions, a microprocessor does three basic things:. There may be very sophisticated things that a microprocessor does, but those are its three basic activities.

The following diagram shows an extremely simple microprocessor capable of doing those three things:. Although they are not shown in this diagram, there would be control lines from the instruction decoder that would:. Coming into the instruction decoder are the bits from the test register and the clock line, as well as the bits from the instruction register. The previous section talked about the address and data buses, as well as the RD and WR lines.

In our sample microprocessor, we have an address bus 8 bits wide and a data bus 8 bits wide. That means that the microprocessor can address bytes of memory, and it can read or write 8 bits of the memory at a time. Let's assume that this simple microprocessor has bytes of ROM starting at address 0 and bytes of RAM starting at address ROM stands for read-only memory. A ROM chip is programmed with a permanent collection of pre-set bytes.

While chips look flat, they are three-dimensional structures and may include as many as 30 layers of complex circuitry. Chips are fabricated in batches of wafers in clean rooms that are thousands of times cleaner than hospital operating rooms. Fab technicians wear special suits, nicknamed bunny suits, designed to keep contaminants such as lint and hair off the wafers during chip manufacturing.

Design specifications that include chip size, number of transistors, testing, and production factors are used to create schematics—symbolic representations of the transistors and interconnections that control the flow of electricity though a chip. Designers then make stencil-like patterns, called masks, of each layer.

Designers use computer-aided design CAD workstations to perform comprehensive simulations and tests of the chip functions. To design, test, and fine-tune a chip and make it ready for fabrication takes hundreds of people.

Making chips is a complex process requiring hundreds of precisely controlled steps that result in patterned layers of various materials built one on top of another. Hundreds of identical processors are created in batches on a single silicon wafer. These first computer chips used relatively few transistors, usually around ten, and were known as small-scale integration chips. As time went on through the century, the amount of transistors that could be attached to the computer chip increased, as did their power, with the development of medium-scale and large-scale integration computer chips.

The latter could contain thousands of tiny transistors and led to the first computer microprocessors. There are several basic classifications of computer chips, including analog, digital and mixed signal varieties. But, you see, one thing all our circuits have in common is that they just take in inputs and do the same operation over them to give the output.

What if I wanted to multiply something, or another time, to add? In this case, we need to not consider bits as just numbers. Let us try to represent the "actions" themselves in bits. Let us say 0 means "add", 1 means "multiply". Now, let us build a tiny circuit that sees a bit as a "command", and selects between two inputs, I0 and I1, and outputs I0 if the command is 0, and I1 if it is 1.

This is a multiplexer. In fact, we can have lots of these multiplexers to choose between so many outputs—then we've got ourselves a truly amazing machine. But wait—we have another idea. Remember those funny little flip-flops we built earlier? Well, what if we plug in a multiplexer at the output of flip-flops?

Now we have what is called a 1 Kilobit memory. We can give it an "address," and it will give us a bit back, which was the bit stored at that numbered location. What's more, these bits can now be either "numbers" data or "commands" instruction.

Here's the really amazing thing: We have everything that we need to build a processor:. This thing you've just built is called a Von-Neumann machine yeah, crazy people like him figured all of this stuff out in Nowadays, people are beginning to question if this is the best way to build things, but this is the standard way any processor nowadays is built.

Well, when I said earlier that this is how all processors are built, I meant "theoretically," and by "theoretically," I mean "let us consider a cow is a sphere" theoretically. You only have Kilobits of memory, your competitor can handle as many as billions Gb or trillions Tb of bits of memory. But now you say, no way in hell those guys can create a billion to one multiplexer and have its data within 1 nanosecond. Their secret sauce is something called locality.

What this means is that your program normally only uses a few locations of data and instruction memory at a time. So what you do is have a large memory consisting of GB's of data, then you bring in a small part of it—the part that is being used currently, to a much smaller array maybe 1 MB called the cache.

Of course, now you can have an even smaller cache below this cache, and so on, till you can get to something that you can read or write to in about the same amount of time you can do an arithmetic calculation. Another powerful idea that you can do is called out-of-order processing. In the normal way, you will just do it sequentially, going one instruction after another and finishing execution in 3 steps.

But, if you have two adders in your system, you can run instructions 1 and 2 in parallel, and then be done in 2 steps. So you execute as much as possible every step and finish your execution faster.

Now, think back to the time when all you knew was a simple AND gate. This thing you built seems so alien from that.