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What is a Math Coprocessor?

Derek Schauland
Derek Schauland

A math coprocessor is a computer chip that handles the floating point operations and mathematical computations in a computer. In early PCs, this chip was separate and often optional, and it was primarily used in computers where Computer Aided Design (CAD) was the primary focus. In today’s computers, it is generally built into the CPU, allowing the central processor to offshore the mathematical computations to this chip. This helps the CPU maintain more processes at one time.

Applications on a PC, like a CAD program or even a spreadsheet, that deal with floating point units (FPUs) and calculations relay on this coprocessor to assist in performing these calculations. This leaves the CPU more available for operating system tasks and overall PC management.

A math coprocessor.
A math coprocessor.

The math coprocessor can be compared to a computer’s graphics processing unit (GPU), a separate card that handles graphics rendering and can improve performance in graphics intensive applications, like games. The coprocessor, though neither as costly nor as noticeable in most PCs, is the workhorse of the chipset for mathematical computations. Considering that the majority of a computer’s actions are mathematical or binary, it plays a very important role, even though it is typically unseen or unnoticed by any computer user.

Because newer computers include this component as part of the CPU, its actions are not visible other than through overall CPU monitoring. While still optional, the fact that it is a part of the overall CPU does aid performance because programs that can make use of these functions will do so without user intervention. Comparing the performance of a spreadsheet on two computers, one with and one without a math coprocessor, should show considerable improvement in performance where the chip is present, assuming that the CPU chip speeds are the same.

Discussion Comments


@allenjo - You would have to have pretty specific, intensive needs to go beyond the math processing capabilities of the modern multi-core processor, especially since you can have several of them now along with a 64-bit operating system that really takes advantage of their power.

Now, if you are talking CAE or ocean current modeling or something, I suppose you need all the hardware you can get.

I used to work as a UNIX administrator and I was able to visit the regional headquarters for Silicon Graphics when they were really big in the movie and design industries, and even one of their high-end desktop machines could be $75,000.

The field engineers took us on a tour of some of their big, enterprise-class servers, and we were told that on some of the big dedicated rendering/modeling machines, the graphics-handling hardware could be hundreds of thousands of dollars.

So, if there is a need, and the money to fill it, I am sure somebody will make what is desired. Probably a lot cheaper, too.


@nightgamer - As far as I know the coprocessor is hardwired into the CPU, and is actually part of the silicon wafer, so there's really no way you could get to it. The programming is set at the factory. You'd have to be part of the engineering of the chips to have any input, it seems.

Now, it may be possible to write a piece of software or program a BIOS chip to alter the way the system interacts with the CPU in the processing of numbers. I really don't know how you would do that.


Here's a nerdy story: Does anyone remember the 486 chip from Intel? Well, it came in two types, the 486 SX and the 486 DX. The SX had no coprocessor, and was cheaper. The DX had a coprocessor built into the chip. You also had the option to buy an "upgrade chip" that turned your SX into a DX. It plugged into a spot on the motherboard next to the CPU.

Simple, right? Not so much.

You see, it turns out it was cheaper to make one kind of chip than to make two. So what they did at Intel was only make DX chips, then on the ones that were going to sell as SX chips for less money, they disabled the coprocessor.

If you had an SX and later decided to upgrade it, the "upgrade chip" was plugged into the motherboard next to the SX. What they didn't tell you was that the upgrade chip was a fully functional 486 DX processor. When you plugged it into the coprocessor slot, the motherboard disabled the original SX processor totally, and only the upgrade chip was used.

I have no idea what would have happened it you just took out the SX chip, sold it, and plugged the "upgrade chip" (or DX processor) into the CPU slot.


@nony - I don't think that the separate math processor is strictly a relic of the past.

Even today, high end graphics applications by physicists and engineers would require a separate co-processor, I believe.

I’ve even heard that Intel is releasing a super powerful math processor as a separate component on a PCI card, for computer users to use alongside their existing computers.

It may be overkill unless you’re doing processor intensive applications, but it will be available to you still.


I had an 8087 math processor back in the early days of the personal computer revolution. I remember how excited I was to have it, even though honestly I probably didn’t need.

I did some light spreadsheet stuff, and had a desktop publishing program and a word processing program.

That was pretty much it. The games I ran back then were in DOS. They may or may not have used the math processor. I think they were just using the graphics pipeline on the motherboard.

To be honest, however, I had nothing to compare against, so I don’t know if I was really getting the full benefit of the math processor or not.


I think that one day there will be no limit to the capacity of mathematical computations on a computer, but it will not be with the standard math processor or CPU on today’s computers.

It will be the result of using nanotechnology to accomplish infinitely more powerful calculations.

Nanotechnology uses thousands of little nanobots, from what I understand, to perform calculations.

Its power is in the collective action of all of these little nanobots working together on math problems, rather than having a big CPU working on the problem.

Think about it this way. Have you ever seen an army of ants pulling a twig or stick? Those ants couldn’t do that individually, but as an army, they can do it.

Those nanobots are like an army of computerized slaves toiling away at mathematical calculations and their combined power is greater than the biggest CPU we have in any computer today. At least that’s the way I understand it.


due to the limited communication (post-manufacturing)ability of the flux capacitor via the cosine spread channel, tweaking the programming would not produce noticeable results other than to produce a misalignment (inaccuracy)at eleven places to the right of the decimal point.


Is there any way a programmer can view and alter or enhance the programming of a math coprocessor and graphics processing unit? I'm interested in how pcs use basic mathematics, esp multiplication.

Is this done directly through the os or in the bios?

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    • A math coprocessor.
      By: ing_masa
      A math coprocessor.