Hardware specification

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One Laptop per Child

Hardware details for OLPC, May 11, 2006

Maintained from a document written by Michael Bove 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 recipe that you can actually buy in the volume you need to manufacture. Sometimes you can substitute ingredients without spoiling the general recipe, and sometimes the result would be inedible. In this case, we have a single chip that Mark Foster is specifying, that sits between the CPU and the display, and over which we have detailed control.

If you'd like some insight into this process, you can look at older versions of this page in the wiki.

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—often to the point of selection of major and minor components—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 (almost 1/3rd of the total made), 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 you can 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 early 2007, 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.

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

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 and the chip that drives it. The electrical interface to the flat panel and the LCD panel itself is now in detailed engineering. A family of flat panels all based on a common LCD panel, but differing on their use of color filters, what kinds of backlights or temporal color, which have different properties (power consumption, resolution, gamut) and risks are being built this summer, and the initial display panel will be chosen from among these designs in September.

Several of these designs are very low risk and do not require innovations in manufacturing, so our initial ship schedule of the OLPC system is now much more certain than in the past. Several other designs are higher risk, but better performance, either on effective resolution or power consumption. It is quite possible we may initially use a low risk panel and phase in one of the alternatives to manufacturing later in 2007. ChiLin of Taiwan will be the manufacturer of the OLPC display. 3M is building specialized plastic optical components being used in the design of these displays.

First Generation System

Physical dimensions:

  • Dimensions: 193mm × 229mm × 64mm (as of 3/27/06—subject to change)
  • Weight: Less than 1.5 KG (target only—subject to change)
  • Configuration: Convertible laptop with pivoting, reversible display; dirt- and moisture-resistant system enclosure

Core electronics:

  • CPU: AMD Geode GX2-533@1.1W
  • CPU clock speed: 400 Mhz
  • Compatibility: X86/X87-compatible
  • Chipset: AMD CS5536 South Bridge
  • Graphics controller: Integrated with Geode CPU; unified memory architecture
  • Embedded controller: Based on ENE 3920
  • DRAM memory: 128MB dynamic RAM
  • Data rate: Dual – DDR266 – 133 Mhz
  • BIOS: 512KB SPI-interface flash ROM; LinuxBIOS open-source BIOS
  • Mass storage: 512MB SLC NAND flash
  • Drives: No rotating media

Display:

  • Liquid-crystal display: 7.5” Dual-mode TFT display
  • Viewing area: 151.6 mm × 113.4 mm
  • Resolution: 1200 (H) × 900 (V) resolution (200 dpi)
  • Mono display: High-resolution, reflective monochrome mode
  • Color display: Standard-resolution, quincunx-sampled, transmissive color mode
  • Special "DCON" chip, that enables deswizzling and anti-aliasing in color mode, while enabling the display to remain live with the processor suspended. Since we will always be running the frame buffer at 1200x900 resolution, the color resolution is lower, but exactly how this works out in effective resolution is complex. Mary Lou Jepsen is planning a document to explain the effective resolution, which is higher than if we simply reduced the size of the frame buffer and used the red, green and blue channels.

Integrated peripherals:

  • Keyboard: 80 keys, 1.2mm stroke; sealed rubber-membrane key-switch assembly
  • Cursor-control keys: Dual five-key cursor-control pads; four directional keys plus Enter
  • Touchpad: Capacitance-sensing touchpad; supports written-input mode
  • Audio: Analog Devices AD1888, AC97-compatible audio codec; stereo, with dual internal speakers; monophonic, with internal microphone
  • Wireless: Marvell 83W8388, 802.11b/g compatible; dual adjustable, rotating coaxial antennas; supports diversity reception
  • Status indicators: Power, battery, WiFi; visible lid open or closed

External connectors:

  • Power: 2-pin DC-input, 10–25V
  • Line output: Standard 3.5mm 3-pin switched stereo audio jack
  • Microphone: Standard 3.5mm 2-pin switched mono microphone jack; selectable sensor-input mode
  • Expansion: 3 Type-A USB-2.0 connectors
  • Maximum power: 500 mA (total)

Battery:

  • Pack type: 6 Cells, 7.2V series configuration
  • Fully-enclosed “hard” case; user removable
  • Capacity: 22.8 Watt-hours
  • Cell type: 7/5AF or 18670 NiMH
  • Pack protection: Integrated pack-type identification
  • Integrated thermal sensor
  • Integrated polyfuse current limiter
  • Cycle life: Minimum 1,000 charge/discharge cycles

BIOS/loader:

  • LinuxBIOS is our intended BIOS for production units.

Environmental specifications:

  • Temperature: somewhere in between typical laptop requirements and Mil spec; exact values have not been settled
  • Humidity: Similar attitude to temperature. When closed, the unit should seal well enough that children walking to and from school need not fear rainstorms or dust.
  • Maximum altitude: -15m to 3048m (14.7 to 10.1 psia) (operating), -15m to 12192m (14.7 to 4.4 psia) (non-operating
  • Shock 125g, 2ms, half-sine (operating) 200g, 2ms, half-sine (non-operating)
  • Random vibration: 0.75g zero-to-peak, 10Hz to 500Hz, 0.25 oct/min sweep rate (operating); 1.5g zero-to-peak, 10Hz to 500Hz, 0.5 oct/min sweep rate (nonoperating)

Regulatory requirements:

  • The usual US and EU EMI/EMC requirements will be met.
  • The laptop and all OLPC-supplied accessories will be fully UL and RoHS compliant.

Photographs of First Prototype Electronics

Power up of the first OLPC electronics prototype boards occurred April 15, 2006. Power and ground testing continued over the weekend, and formal debug and BIOS bring up started Monday, April 17, 2006 at Quanta Computer's labs in Taipei, Taiwan. By Wednesday, April 19, Linux was booting on the first generation prototypes.

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 a next generation 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.

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