More about One Laptop Per Child and its XO Laptop

Dave Moon pointed me to this article, in which a BBC reporter brings an XO home from Nigeria and gives it to his nine-year-old son to try out. There’s also a 3:34 min video of the boy playing with the XO.

http://newsvote.bbc.co.uk/mpapps/pagetools/print/news.bbc.co.uk/1/hi/technology/7140443.stm

More stuff:

http://www.technorati.com/tag/One+Laptop+Per+Child

The rest of this blog pointing consists of some more fun facts about the XO/OLPC, from an interview with Mary Lou Gepsen (the CTO) in ACM Queue Nov/Dec 2007 (very slightly edited by me):

Generators make really weird power. Sometimes the frequency is as low as 35 hz, and the OLPC’s AC adapter has to do “really interesting” power conditioning. The laptop itself can take between negative 32 volts and 40 volts, and works well with anything from 11 to 18 volts. You can plug a car battery into it, or a solar cell, or a bicycle or wind powered generator. India has this cow-dung system that creates methane that drives a generator. Even that will work.

We run the mesh network at extremely low power: 400 milliwatts, compared with my ThinkPad laptop, which uses approximately 10 watts just to run Wi-Fi.

We had to fix a couple of bugs with the chipsets to make sure that they can talk to the flash memory, which operates at very high speed. We had to do wear leveling on the flash. Luckily we’ve got David Woodhouse, who wrote JFFS2 (Journaling Flash File System, Version 2), on the project.

We put memory into directly into the display itself. That means the screen can stay on while the rest of the motherboard or the chipset is off. The way to get to low power — the big secret — is to turn off stuff that you’re not using. But nobody has ever made a laptop with a screen that self-refreshes.

We also put a tiny ARM core into our Wi-Fi chip. We used the Marvell chip because it’s the only Wi-Fi chip with a tiny ARM core in it, which means the Wi-Fi can also stay up and running while the CPU is off. [This is important because the machine is part of a mesh network. -- DLW]

We put the motherboard behind the screen so the kid can use the XO machine on his or her lap and it won’t get too hot like a normal laptop. These are the first truly laptop-use computers made in the last decade.

In Libya, it gets up to 57 degrees C [134 degrees F -- DLW] in the desert. But the safe (read: don’t explode) NiMH (nickel-metal hydride) batteries won’t recharge above 45 degrees C. That’s a real problem because many spots in Libya are off the grid. But the lithium ferro-phosphate batteries charge in heat up to 60 degrees C. The machine can handle many different battery chemistries, which was a real pain. We did that in the embedded controller.

Our battery has a five-year life. You can go to 2,000 charge/recharge cycles. The lithium ion battery in my ThinkPad is supposed go to for 500 charges, but in practice it’s more like 200. So, moving to lithium-ferro-phosphate is really cool because you don’t have to spend additional money on periodic battery replacement costs, regardless of the environment.

We do 15 times better than Energy Star compliance. Where a typical laptop has maybe a one-, two-, or three-year maximum lifetime in office workplaces, ours is double that at five years — and we do this in extreme environments to boot. Our machines are half the size and weight of a typical laptop, and our laptops are repairable by children and by locals. You can change out plastic parts quite easily, including the screens. Five-year-olds can change the screen on our laptops because it’s actually that easy.