An entirely new laptop

The display is sensational, the envisioned power consumption record- breaking, and operation different from the ground up - not just intuitive, but playful in the ideal case. The OLPC is considering a mechanical generator to provide power where electricity from wall sockets is a luxury. c't received a prototype from the first batch for a test drive.

The XO's mainboard is found behind the panel in the display lid. AMD's Geode is in the middle, with the Southbridge to the right.

Design Continuum designed the original laptop, with Fuseproject taking up the design for the prototypes now available. The XO is an inch smaller than a 12-inch notebook and weighs around one kilogram with the battery. Because the mainboard is in the lid behind the display, the bottom part of the laptop containing the keyboard is very thin – ideal for children's hands. The keys are also specially designed for this target audience with a width of 13.3 millimeters, compared to the 19-millimeter keys used on notebook keyboards for adults.

The bottom half of the laptop extends behind the display when closed, exposing a stable handle. When the display is opened, the handle prevents the laptop from tipping over to the back due to its relatively heavy lid. The opened machine is expected to be robust against dirt and drops of water. The laptop's case thickness measures two millimeters, which also increases the robustness of the units.

The core of the mainboard is a 366 MHz Geode GX2-500 processor with a mere 32 KB of cache. The x86-compatible CPU is otherwise mainly found in embedded hardware. It contains an integrated graphics chip and Northbridge, but the Southbridge AMD CS5536 rides on its own chip with USB 2.0, audio, and an IDE connection with a data connection of 32 MHz. The system has its own memory controller because the one in the Geode system was too slow for the developers.

While the computing performance does not nearly match that of current notebooks, the Geode 500 also peaks at a consumption of 3.5 watts, with the chipset making do with less than one watt; Geode systems have been optimized for especially low power consumption. Since the mainboard can do without a fan and a cooling system completely in light of these values, it fits into the lid behind the display.

The laptop will have 256 MB of DDR 266 DRAM but no hard drive, storing data instead on 1024 MB of NAND flash memory (prototype BTest- 1 has 128 MB DDR and 512 NAND flash). The XO also does without an optical drive, meaning that it has no moving parts inside. Extensions can, however, be added via USB slots and a single SD card slot.

Data can be stored on a school computer via WLAN. The OLPC plans to provide such a server with 330 gigabytes of memory for roughly 100 US dollars. Unfortunately, the first such server has yet to be seen. Few schoolchildren live near their school; most live near other schoolchildren. So the developers came up with something clever for wireless connections between XOs via WLAN: the WLAN chips operate as a mesh, with each laptop passing on data for others. Less infrastructure is needed in such mesh networks; in extreme cases, all that is needed is a single WLAN base station to get all of the schoolchildren connected to the Internet.

As "mesh point portals", individual XOs keep in contact with the WLAN base station providing access to the Internet. Each one passes on data to the other mesh points. The entire mesh works from one and the same WLAN interface. The OLPC laptop is the first implementation of the IEEE's 802.11s standard for mesh networks [1].

Marvell's 88W8388 USB WLAN chip presented at the beginning of 2005 provides a connection to this network within the XO. The chip contains an ARM processor core in addition to a bit of RAM as firmware memory; it communicates in accordance with IEEE 802.11g. Thanks to its ARM core, the WLAN controller can even stay in contact when the XO is switched off. But you shouldn't expect to break any speed records with a WLAN mesh: the typical data rate across multiple nodes would be pretty slow for DSL at one to two megabits per second. But that would be enough to look something up in an online encyclopedia or to communicate by e-mail and chat. Above all, the mesh serves to network children without any external connections. In fact, the XO is even useful for video conferences via Skype or Telepathy thanks to the installed camera and microphone.