Hardware specification

=Hardware details for OLPC, 24 Dec. 2005= V. Michael Bove, Jr., updated by Jim Gettys.

Hardware Design Process
Designing hardware is much more constrained than software; while you may sometimes have great influence on the design of a chip many months in advance of availablility, you can only actually use chips which you can get in the volumes required at prices that you can afford. Even a single missing component, or component not available in the quantities you need, may cripple your production. Many in the software community, who are used to more fluid ability to modify design and produce in unlimited copies, find this a foreign concept.

Designing hardware is similar to making sausage: you may be able to grow new ingredients starting long in advance if you are friendly with farmers (chip designers). You can only make your sausage, however, with the ingredients required by your recipie that you can actually buy in the volume you need to manufacture. Sometimes you can substitute ingredients without spoiling the general recipie, and sometimes the result would be inedible.

High-Volume Design and Manufacturing
Furthermore, production of high-volume hardware is now a very specialized business, and is now often joint between the organization/company that specifies what the hardware should do&mdash;often to the point of selection of major and minor components&mdash;and an ODM (original device manufacturer), which specializes in very high-volume design and production. The ODM generally does the detailed design for production; e.g., exact part selection if there are variants, schematics, layout, board routing, mechanical design, testing, debugging for production, logistics, and production of the finished goods.

In OLPC's case, the ODM is Quanta, as announced in mid December. There is a good chance that your laptop was manufactured by Quanta, headed by Barry Lam, which is possibly the largest company few people have heard of. Quanta manufactures more laptops than any other company in the world, whether branded HP or Apple or others. Detailed design of the first production OLPC design is just starting, though OLPC has investigated (and continues to investigate) the possible components and other design tradeoffs.

Note that CPU chip manufacturers generally provide sample designs, development boards, and application notes, that are often complete and usable by themselves, though often include interfaces or hardware you might not choose in volume production. These clarify how their products might be "designed in" to actual products. Our prototype machine seen at Tunis was using one of the AMD "Rumba" boards. It approximated much of the first OLPC hardware, though used a conventional disk rather than NAND flash, and has components we will not use (e.g. ethernet), and that conceptual (but working) model lacked the much cheaper flat panel that is under development.

Detailed schematics and layouts of such sample AMD designs are generally available in the chip manufacturer's developer programs. If you are interested in exact design details of hardware could you get for immediate experimentation, we direct your attention to these programs, which generally include the ability to buy such sample hardware. Most of the information required to program devices, however, is completely freely available at the manufacturer's web sites in fully public specifications.

In concert with ODMs, such sample designs are generally customized to fit the exact product needs and engineered for high-volume-production tooling and techniques that are not applicable to low-volume development-board runs. OLPC has just entered in partnership with Quanta on this engineering-for-production phase of the project.

Detailed schematics and board layouts of these high-volume designs are often considered proprietary to the ODM's, or jointly owned by both parties involved. They represent the competitive advantage one ODM may have with its rivals (who may have access to the same components as they do). Those design schematics are sometimes available to programmers after production starts under NDA agreements; for example, schematics of many of the iPAQ handhelds were made available to programmers in the open-source community under NDA, when insufficient written programming information was available. OLPC will try to document our designs sufficiently to avoid NDAs; we expect this will be less effort than the logistics of requiring NDAs in such a large and diverse community.

Forseeable Designs
Currently we can forsee three generations of machines: a first one to ship in late 2006, a second production run sometime in 2007 that will incorporate a newer AMD chip and possibly a newer wireless chip, and an E-Ink (or other low-power, bistable display technology) based machine to ship when this new display technology is available at an appropriate price point. The further out, the fuzzier the crystal ball.

We will try to keep this specification up to date as more and more details of the first design (and subsequent designs) are nailed down, provide links to specifications for the chosen components, and provide information required to program them (e.g. address space assignments). The first generation design uses already available components, with the (major) exception of the new flat panel. The electrical interface to the flat panel is not yet complete.

Subsequent OLPC designs may use components that have not yet been shipped by their manufacturer, and we may have to arrange a program whereby the open source community can get early access to specifications of those components for driver development.

First Generation System
Details of the first generation are firming up as of the date of this document, and are closely related to the CPU and CPU support chip chosen:


 * Processor: AMD Geode GX500@1.0W with AMD CS5536 companion chip (note that the "500" chip really operates at a 366MHz clock).
 * Memory: 128MB DRAM, possibly DDR Mobile
 * Nonvolatile storage: 512MB (possibly 1GB) NAND flash memory
 * BIOS/loader: hardware details TBD; either conventional, or maybe LinuxBIOS, if available in time.
 * Audio: AC97 codec (chip TBD; we are down to probably two or three alternatives), built-in stereo speakers and mono microphone, jacks for external stereo speakers and microphones
 * External ports: four USB2.0, one supporting On-The-Go functionality
 * Display: dual-mode, based on a 7.2" diagonal 800x600 monochrome TFT panel
 * Monochrome (high-res, low-power "E-Book") mode: 800x600, reflective (ambient light)
 * Color mode: 462x346, quincunx-sampled, LED-backlit
 * Input devices: keyboard, trackpad (supporting pointing, scrolling, and possibly graphical input), additional buttons adjacent to screen for use in E-Book/tablet mode
 * Wireless: Atheros AR5004G or AR5004GS chip, 802.11b/g. The requirements of mesh networking in combination with the abilities of the madwifi device driver have driven this selection; it is the best and most flexible wireless device driver today. There are not other viable alternatives at this time.
 * Power: 100-240VAC, 12VDC, also integrated crank charger based on a permanent-magnet generator and 100:1 gear train. Battery details TBD.

Many of the TBD's should be set by late January, 2006, and we'll try to keep this page up to date.

The display is the only part of this design which is actually novel. At this moment, we are pursuing two possible designs in parallel to reduce risk. We will probably not have final details on the display's details until after first samples can be evaluated in several months.

Second Generation Design
Second-generation unit will use a more power-efficient integrated Geode-based AMD chip (instead of the GX500/5536 set) and probably the Atheros AR6001G or similar wireless chip. Feedback window on design of the next AMD chip will close in March 2006, so it's important to maintain dialogue with AMD regarding Gen 2.