On the XO Laptop

XO-Laptop Hardware Summary

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[First published as XO-Laptop Hardware Summary on November 29, 2007.]

I will make mention of some of the hardware features of the XO Laptop in forthcoming posts. I have previously cited Wikipedia’s XO description. However, I just came across a description at the OLPC site that is more authoritative, so I am taking the liberty of summarizing some of the key information from the XO Hardware specification here.

Physical dimensions

* Approximate dimensions: 242mm × 228mm × 32mm (see drawing to the right for detailed dimensions)
* Approximate weight:
o XO laptop with LiFeP battery: 1.45KG (~3.20lbs);
o XO laptop with NiMH battery: 1.58KG (~3.48lbs);
* Configuration: Convertible laptop with pivoting, reversible display; dirt- and moisture-resistant system enclosure; no fan.

Core electronics

* CPU: x86-compatible processor with 64KB each L1 I and D cache; at least 128KB L2 cache;
o AMD Geode LX-700@0.8W (datasheet)
* CPU clock speed: 433 Mhz;
* ISA compatibility: Support for both the MMX and 3DNow! x86 instruction-set extensions;
o Athlon instruction set (including MMX and 3DNow! Enhanced) with additional Geode-specific instructions
* Companion chips: PCI and memory interface integrated with CPU;
o North Bridge: PCI and Memory Interface integrated with Geode CPU (info)
o South Bridge: AMD CS5536 (datasheet)
* Graphics controller: Integrated with CPU; unified memory architecture;
* Embedded controller: ENE KB3700 or ENE KB3700B;
o Embedded Controller: ENE KB3700
* DRAM memory: 256 MiB dynamic RAM; data rate: dual-DDR333-166Mhz;
* BIOS: 1024KiB SPI-interface flash ROM;
* Open Firmware used to load the operating system;
* Mass storage: 1024 MiB SLC NAND flash, high-speed flash controller;
* Drives: No rotating media.
* CAFE ASIC (camera- and flash-enabler chip provides high-performance camera, NAND FLASH and SD interfaces); Marvell 88ALP01: CAFE Specification


* Liquid-crystal display: 7.5” dual-mode TFT display;
* Viewing area: 152.4 mm × 114.3 mm;
* Two modes: (1) grayscale (B&W) reflective mode (for outdoor use—sunlight-readable); and (2) color backlight Mode (for indoor use);
o reflective mode: high-resolution (200 DPI), 1200(H) × 900(V) grayscale pixels, power consumption 0.1–0.2Watts;
o backlight mode: built in sub-pixel sampling of the high-resolution display results in approximately 800(H) × 600(V) color pixels, power consumption 0.2–1.0Watts;
* The display-controller chip (DCON) with memory that enables the display to remain live with the processor suspended. The DCON also formats data for the display.
* This Liquid-crystal display is the basis of our extremely low power architecture. The XO is usable while the CPU and much of the motherboard is regularly turned off (and on) so quickly that it’s imperceptible to the user. Huge power savings are harvested in this way (e.g. by turning stuff on the motherboard off when it’s not being used (if even for a few seconds), while keeping the display on).

Note: web browser images are currently scaled up so that an image of very roughly [800 × 600] fills up the browser window.

eToys (Squeak)running on the OLPC display

Integrated peripherals

* Keyboard: 80+ keys, 1.0mm stroke; sealed rubber-membrane key-switch assembly;
o Keyboard Layouts
o Layout pictures: English, Arabic, Thai, West African (Nigeria), Portuguese, Spanish, Amharic, French (not final), Urdu, Cyrillic, Turkish (not final), Nepali, Mongolian, Kazakh, Devanagari, Uzbek, Pashto, Dari
* Gamepad: Two sets of four-direction cursor-control keys;
* Touchpad: Dual capacitance/resistive touchpad; supports written-input mode;
o ALPS Electric Dual capacitance/resistive touchpad;
* Audio: AC’97 compatible audio subsystem; Internal stereo speakers and amplifier; internal monophonic microphone; jacks for external headphones or microphone;
o Analog Devices AD1888 and Analog Devices SSM2302 for audio amplification

Keyboard detail

* Camera: integrated color video camera; 640 x 480 resolution at 30 FPS; independent (and undefeatable by software) display of microphone and camera recording status; the camera and device driver support disabling AGC and automatic color balancing, to enable its use as a photometric sensor for educational applications;
o Omnivision OV7670
* Wireless Networking: Integrated 802.11b/g (2.4GHz) interface; 802.11s (Mesh) networking supported; dual adjustable, rotating antennas support diversity reception; capable of mesh operation when CPU is powered down;
o Marvell Libertas wireless chipset, 88W8388 controller and 88W8015 radio
* Status indicators: Power, battery, and WiFi (2), visible with lid open or closed; Microphone In-Use, and Camera In-Use, visible when lid is open.

External connectors

* DC power: 6mm (1.65mm center pin) connector; 11 to 18 V input usable, –32 to 40V input tolerated; power draw limited to 15 W;
* Headphone output: standard 3.5mm 3-pin switched stereo audio jack;
* Microphone input: standard 3.5mm 2-pin switched mono microphone jack; selectable 2V DC bias; selectable sensor-input mode (DC or AC coupled);
* USB: Three Type-A USB 2.0 connectors; Up to 1A power supplied (total);
* Flash Expansion: SD Card slot.


* Pack type: 2 or 4 cells LiFePO4; or 5 cells NiMH, approx. 6V series configuration (subject to change);
* Capacity: 16.5 Watt-hours (NIMH), 22 Watt-hours (LiFeP);
* Fully-enclosed “hard” case; user removable;
* Electronics integrated with the pack provide:
o Identification;
o Battery charge and capacity monitoring chip (Maxim DS2756 data sheet);
o Thermal and over-current sensors along with cutoff switch to protect battery;
* Minimum 2,000 charge/discharge cycles (to 50% capacity of new).
* Power Management will be critical

BIOS/loader Open Firmware (including hardware initialization and fast resume).

Environmental specifications

* Temperature: UL certification planned to 45C in Q32007, pending 50C certification in mid-2008;
* Humidity: UL certification planned to IP42 (perhaps higher) when closed, the unit should seal well enough that children walking to and from school need not fear rainstorms and 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);
* 2mm plastic walls (1.3mm is typical for most systems).

Regulatory requirements

* The usual US and EU EMI/EMC (electromagnetic-interference and electromagnetic-compatibility) requirements will be met;
* The laptop meets IEC 60950-1, EN 60950-1, and CSA/UL 60950-1 specifications. It also complies with UL 1310 and UL 498. In order to guarantee the safety of children using the laptop, it passes ASTM F 963;
* The external power adapter complies with IEC, EN, and CSA/UL 60950-1;
* The removable battery pack complies with IEC, EN, and CSA/UL 60950-1 and UL 2054;
* RoHS (Restriction of Hazardous Substances Directive – EU) compliant.

Serial Adapter 3.3V TTL to RS-232/USB Adapter


Written by daveshields

December 12, 2007 at 3:10 pm

Posted in xo-laptop

One Response

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  1. […] this for a comparable summary for the […]

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