One Laptop Per Child: Charity, Prosperity, & Capitalism In The Developing World

The XO-1 Hardware

Given the conditions that the XO-1 was built to endure, virtually all parts of the XO-1 deviate from traditional laptop designs. Externally, the case needs to be able to withstand harsh environments, including heat and water, requiring that the entire thing be built to standards similar to those of mass-market high-durability laptops (e.g. the Panasonic Toughbook) which strike a balance between usability, cost, and protection. The plastic casing as at least 2mm thick in all covered locations, and the laptop is lightly sealed when packed up for travel. As an added level of durability, the keyboard is completely sealed, preventing the most common destination of spills from getting inside the machine.

Besides the physical requirements of such a laptop, the XO-1 is also built to deal with the logistical problems of where the laptops are intended to go, mainly the power problem. The laptop is already a sub-notebook in size for several reasons, but even most sub-notebooks have a relatively high power requirement, which is a problem when it comes to generating heat, running off of a small battery, and working with an acceptable recharge source. Much of the hardware as a result has been selected for power usage, if not already for physical constraints.

Specifications:

• AMD Geode LX-700@0.8W, 433mhz
• Chipset: AMD CS5536 Southbridge
• Graphics: Integrated
• Memory: 256MB DDR-333
• Mass storage: 1024MB SLC NAND flash
• Display: 7.5" Dual-mode TFT display, 1200 x 900

At the core of the system is AMD's Geode LX processor, a near system-on-chip design that incorporates an x86 processor core along with Northbridge functions and the video controller. As a distant relative of the Cyrix MediaGX processor, performance is in no way notable with the Geode LX, but with the integration of features and a low clock speed of 433MHz it has a very attractive power profile for an x86 chip. Maximum TDP/power consumption is only 3.1W, with an average power consumption measured in milliwatts.

A hard drive is out of the question due to the high power usage, the high costs in manufacturing, and the lack of durability. Instead the system uses 1GB of flash memory as its primary storage, far smaller than a hard drive but also far more suitable for the design. Optical drives are also not included for the same reasons, so external storage is handled via SD cards and USB devices.

Due to the small amount of primary storage, wireless communication has a high precedence on the device and is the main method for accessing data. To that extent the laptop features a Marvell 802.11b/g controller and uses a pair of antenna (the so-called "ears") for best reception. The WiFi controller like the rest of the hardware is also optimized for power as WiFi is another major power drain. We're not entirely sure how it has been optimized but we believe that this is via a reduced transmission rate.

The WiFi module also serves a secondary purpose on the unit, which is the formation of a full-time wireless mesh network. When the laptop is powered down, the WiFi module can stay operational and route wireless traffic so that other laptops in the area can be linked together as part of one large mesh. By having an active mesh children are not limited in who they can wirelessly communicate with as long as they can see at least one other node of the mesh, and it allows all the laptops in the mesh to share internet access in a wider area if it's available. It's one of the more novel elements of the XO-1 hardware, and the OLPC organization estimates a XO-1 can run for an impressive 40 hours in its router mode.

Because the XO-1 is intended to pull double-duty as a laptop and an eBook reader, it has a very unusual screen that is both backlit and reflective. When reflecting light the screen operates as a 1200x900 6-bit grayscale screen, as the reflective layer sits above the color components. This mode uses a minimal amount of power because there is no need to drive a backlight, ideal for use as an eBook. When the backlight is activated the unit can produce 6bit color (assuming that the majority of the light is coming from the backlight), although the design of the color filter is such that the unit loses some of its effective resolution compared to grayscale mode.

The power system of the XO-1 is also worth mentioning, again an example of the rugged design. The initial designs for the XO-1 floated several ways to recharge the unit assuming a regular electrical grid was not available, including an integrated hand crank. The OLPC organization has since then opted to not build in any such charger; instead the unit has a DC input that can handle highly variable voltages (-40V to 40V) so that the unit can safely be hooked up to any number of power sources, including solar or pedals. While the initial units will be shipping with a traditional (albeit well built) NiMH battery, future units are planned to ship with a higher density exotic LiFePO4 battery, once mass production of those batteries begins.

Unfortunately, the OLPC organization missed its initial price target on the XO-1 by a good amount. The goal was $100, but the actual price looks to be closer to $175. While it's only a $75 difference, that amounts to the laptop coming in at 75% more than was intended. Until costs further come down, the XO-1 will likely remain unaffordable to some of the target nations.