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What Is CPU design?

A dual core CPU mounted to a motherboard.
A Central Processing Unit (CPU).
An Intel quad core CPU.
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  • Written By: Alex Tree
  • Edited By: Heather Bailey
  • Last Modified Date: 16 July 2014
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Central processing unit (CPU) design is the design of an important aspect of a computer. The design is usually carried out by a computer design engineer specializing in CPUs. In general, the first step of CPU design is deciding what the design priorities are and what goals are to be achieved with the CPU. Designing a new CPU can take up to five years, sometimes longer, and the total cost of the design period can range into the tens of millions of United States Dollars (USD). These costs vary depending on the type of CPU, which can range from high performance to low-end CPUs for embedded devices and general purpose models.

A few areas of CPU design must always be addressed, including the integration of an instruction set that programmers can use. Without an instruction set, programmers are not able to develop programs that run on a computer using a given CPU. The instruction set specifies a lot of basic information, such as how to read and write data and where specific things such as memory are located.

Another integral part of CPU design is designing the physical representation of the hardware. Since designing a CPU is a complicated, time-consuming process, it is typically necessary to use a computer simulator to visualize all of the prototyped hardware. In most cases, many CPU designers work together on this aspect of CPU design.

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One of the final steps of CPU design is called design rule checking. The purpose of this process is to ensure that the CPU design satisfies technical rules used to make sure the chip is manufactured effectively. Manufacturing is not a perfect process, so there are typically variables and imprecise actions. The design of a chip must be able to withstand some errors during manufacture but still operate properly.

Some common design goals exist when designing a new CPU, and there is often more than one goal for a given CPU. Sometimes a designer wants to make a CPU that can do more with less. The goal might not be to make a CPU that is much faster than existing designs, but to produce a certain standard that is cheaper or more energy-efficient. In other cases, the goal might indeed be to build a faster CPU with no regard to cost or power use. Another type of design goal might be to build a CPU that works better when used in parallel computing or more efficiently with certain types of processes.

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Discuss this Article

anon326358
Post 6

@MrMoody: About the second part of your post. That's not necessarily true. A while ago (I believe it was Intel) had that happen to them, where they shipped out a flawed chip. However, what they did was hand out "rebate" cards for new free chips to customers. They made them do the work to get the new chip. After it was all over, they only had to replace about 1 percent of all the faulty chips they sold, which is not much of a money loss.

starrynight
Post 5

@Azuza - I share your amazement. I bet your probably have to go through a good amount of schooling to design CPUs.

But, after all that schooling CPU designers are handsomely rewarded for their skills. I did a little bit of looking around online and it looks like the median salary for a CPU design engineer in the US is 79K per year.

Azuza
Post 4

I think it makes perfect sense that different CPU's are designed for different purposes. For instance, a netbook doesn't need as much processing power as a high end tower computer that's meant for graphic design!

I'm really amazed at the people who design these things though. They must really be able to think outside of the box, so to speak.

MrMoody
Post 3

@David09 - Yeah, there is a lot riding on the processor design. All of those resources are brought to bear down on one little chip.

That’s why it really causes a shakeup in the industry when the chip manufacturer discovers a flaw in its chip. That doesn’t happen often, but it does happen, and when it does they stand to lose close to a billion dollars in sales.

David09
Post 2

@SkyWhisperer - If you’ve ever seen a video of how the processor architecture is built you know that there is something more than technology involved there; it’s an absolutely perfect manufacturing environment.

A single particle of dust can destroy the whole chip. So these workers have to don masks and gloves, almost like they worked in a hospital, and enter a hermetically clean room where they work on the chip. It’s really quite amazing.

SkyWhisperer
Post 1

In my opinion there is no such thing as simple CPU design. CPU architecture is built on a microscopic level; it still amazes me how they can pack so much circuitry and technology onto a thin wafer.

I realize that they must be using some advanced electron beam lasers or things like that to do all of that sophisticated etching.

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