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On the XO Laptop

The Power of the XO Laptop is its Power Supply

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[First published as on November 25, 2007.]

We have all heard someone say, “More power to you.” But when it comes to discussing the new XO laptop, the XO design team can brag, “Less power from you.” This is why I consider the XO the first “terraputer,” a small computer that can be deployed on a global scale, yet requiring minimal power consumption.

The new XO laptop from the OLPC (One Laptop Per Child) Project has many advantages, but to me the single most important fact about the XO is that the key features seem to be either ignored in discussions about this new machine, or just treated as among the laundry list of new features that come with any new product.

Here are the features that matter most, as described in a recent (October 2007) article from the OLPC Team, OLPC XO: The Greenest Laptop Ever Made, (emphasis added, my comments in italic):


Congratulations to Mary Lou Jepsen!

By combining the XO computer’s power management, including the LiFePo4 battery, with its highly rugged yet low toxicity case, she earned an amazing triple play:

The XO laptop has earned the highest environmental certifications: it is in full compliance with the European Union’s rigorous RoHS(a) standards; it has qualified for Energy Star 4.0 Category A (the most stringent ranking); and it has received the US PC and notebook environmental ratings agency EPEAT Gold(b) rating, one of only eight laptop computers to do so.

In fact, the last we heard Mary Lou was working on a take-back policy with Quanta Computer so that no XO laptop will end up in a landfill – anywhere.

Now thinking of the conversations I’ve had with her, I know she’ll credit her whole team of gifted designers for the realization of her hardware design dream:

“In developing the XO laptop, OLPC had the goal of creating a child-friendly educational tool that inspires creativity and learning for children all over the world,” said Mary Lou Jepsen, chief technology officer at OLPC.

“But equally important for us was to produce a laptop that could be used in remote areas with unreliable or limited energy sources. The result is a laptop computer that has more than 10 times less environmental impact than the average laptop computer. It’s the greenest laptop ever made, and that’s not just its color.”


For example, the XO is a “laptop that could be used in remote areas with unreliable or limited energy sources.” It thus meets a crucial need in humanitarian assistance and disaster relief. See terraputer xo-laptop: Saving Lives Using the XO Laptop and terraputer, xo-laptop xo-sahana: A historic occasion, using the XO Laptop to run Sahana

Here are some consequences of this design:

  • The XO idles at a single Watt of electricity instead of the 70 or so used by conventional laptops.
  • If everyone converted from current laptop technology to XO technology, power used would go down over ninety percent.
  • The XO has NO moving parts.
  • When running, the XO requires about a tenth the power of current laptops.

Let me try to make the issue of power consumption more concrete.

Let’s assume that in the United States a kilowatt-hour of electricity costs $.10 (I pay close to .20, and graph in article says U.S. national average is .12, but we are just looking for rough approximation here.)

Let’s say the XO laptop takes 10 watts when running, though I have seen articles suggesting it is less.

Let’s assume an XO is used in a town or village about 14 hours per day, seven days a week. This would allow for use during school hours and also at night while teachers and others use the XO to learn about it, to prepare lesson plans, and so forth.

Thus, one XO runs 100 hours per week, using 10 watts per hour, consuming 1,000 watts, or one kilowatt. That kilowatt costs $0.10 in the US, for a weekly operating cost of $0.10, or ten cents.

Let’s assume the XO is used fifty weeks a year. This would requre 50 * $0.10, or $5.00 (five dollars) per year.

Now suppose we use a conventional laptop that uses current technology. Such laptops, running all the time, with the hard disk spinning (remember the XO has no hard disk, as it has no moving parts), take about 100 watts, about ten times more power.

This is key: the XO requires about one tenth the power of current laptops.

Thus, the conventional laptop would require not five dollars per year, but fifty dollars, $50.00.

Articles in the newspaper and trade press often say the XO is too expensive, saying it currently costs $200 when it was supposed to cost $100. However, the XO is so much cheaper to operate that the extra hundred dollars can be recouped within a year.

Let’s look at the basic XO hardware:

  • 400 Mhz CPU
  • 256 MB main memory (DRAM)
  • 1 GB “disk” (flash memory

Note that the XO has no moving parts, save the hinge and keyboard keys.

This is a very modest computing device by current standards. For example, most cellphones and iPods are much more powerful.

But it does exist, and it can be used to do useful work.

Now let’s see if Intel could match this. The first question the design team would ask is, “Does it need to run Windows Vista?”

The answer would most likely be, “Of course. Vista is the latest version of the Windows operating system. Just reduce the memory and disk requirements to the bare minimum needed to run Vista.”

As best as I can tell, the bare minimum needed to run Vista is about

  • 1 GB CPU, (two times faster than the XO)
  • 1 GB DRAM memory (four times bigger)
  • 4 GB disk (four times bigger)

These are estimates, and one could chew on them a bit, but I think it safe to say that Linux is as least three times more efficient in using the key computing resources, be it central processor speed, main memory size, or hard disk space needed to hold the operating system code.

So if Intel and/or Microsoft decided to join this race to create a rugged computer capable of being used anywhere in the world, then the possible outcomes include the following.

If Intel meets the power consumption standards established by the XO then Intel will have made a major contribution to improving the environment, and the XO software can then be ported to Intel’s new platform (this would not be difficult), so that Intel can become the hardware supplier of the OLPC project.

If Intel can meet the power consumption standards of the XO and also run Microsoft Vista, then we will have at hand an improved XO that is at least three times better than the current prototype.

If Microsoft can reduce the memory requirements of Vista to 256 MB and 1GB of disk then we can all ask why it took them so long to do this, as the need for new hardware to run Vista is the main impediment to its adoption by non-profit and educational organizations, since these organizations cannot afford to update hardware just to meet increased requirements of a new release of an operating system. (In the non-profit sector every dollar counts. For example, just ask the folks who run the Bill and Melinda Gates Foundation.)

I’ll leave some of the other outcomes as an exercise, but they all say essentially say the same thing.

By proving that a small laptop can be built that:

  • provides a ten-fold reduction in power consumption
  • is based on free and open-source software to require minimal memory and disk, with no moving parts
  • includes microphone, three USB ports, speaker, and video camera;
  • can be built now for $200

the OLPC project has already set a new benchmark in computing technology, one that provides a platform that can now be used to deploy free and open-source software on a global scale for the benefit of humanity, including:

  • education
  • humanitarian relief and crisis/disaster management
  • reducing impact of computing technology on the environment
  • demonstrating that power requirements of embedded devices such as cellphones can be reduced even further
  • provided a convincing demonstration of the power of open-source technology
  • provided a convincing demonstration of the power of technology based on open standards
  • provided a strong reason for open-source developers to start participating in the OLPC project
  • provided by way of new technology a way to spur innovation in other areas. For example, how could you use an XO laptop in an animal shelter?
  • put the fun back into programming
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Written by daveshields

December 12, 2007 at 2:50 pm

Posted in xo-laptop

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