Here are some technical notes I wrote up about the OLPC XO-1 and its unique display and hardware, problems and successes, etc, back around November 2008:

http://donhopkins.com/home/documents/OLPC-Notes.txt

OLPC: One Laptop Per Child (XO-1)

Summary by Don Hopkins (dhopkins@DonHopkins.com).

+ Mission

+ Education.
Educational content, games, simulations, learning tools,
programming languages.
+ Literacy.
eBook, creative writing, journalism.
+ Constructionist learning.
Seymour Papert, Alan Kay.

+ Goals of the XO-1 Hardware Design:

+ Minimal power consumption, with a design target of 2-3 W
total power consumption.
+ Minimal product cost, with a target of $100 per laptop for
production runs of millions of units.
+ A "cool" look, implying innovative styling in its physical
appearance.
+ E-book functionality with extremely low power consumption.
+ The software provided with the laptop should be open source
and free software.

+ Display

+ Designed by Mary Lou Jepsen.
+ 1200x900, 200 dpi, 6x4 inch (152.4x101.6 mm), 6 bits (262k colors).
+ Pixel size 0.127 mm, about 1 arc minute.
+ You can always see 200 dpi grayscale, even in direct sunlight.
(reflective layer)
+ You can get color from the LED backlight.
+ Colors wash out as the sunlight gets brighter.
+ The backlight uses power (though not nearly as much as cold cathode
fluorescent backlight).
+ You can turn the backlight down or off to conserve power.
+ Turning off the backlight tells screen to give slightly higher
resolution, to make reading comfortable.

+ Display Design Goals:
+ Maximize the number hours of ebook reading.
+ Minimize the power consumption.
+ Maximize the resolution and readability.
+ Mesh with how human perception works.
+ Display sharp high quality text, that's easy on the eyes
during the day (reflective) and night (backlight).

+ Critical design innovations:
+ Remove the subtractive color filters that absorb 85% of the light.
+ Replace them with plastic diffraction gratings and lenses,
stamped like DVDs.
+ Much brighter display for a given amount of backlight.
+ Can be manufactured with existing technologies and processes.
+ Uses efficient environmentally friendly LEDs,
instead of fragile, expensive, high voltage, cold cathode
fluorescent lamp backlights.

+ Combination of two separate screens: sharing an LCD glass.
+ One normal backlit screen.
+ Another normal reflective screen.
+ LCD is 1200x900 square grid, with 64 gray levels (6 bits).
+ Off pixels transparent, on pixels opaque.

+ Backlit screen shines through a color filter on the 1200x900 grid.
+ Filter gives each pixel just one color: red, green, blue.
+ Individual grayscale pixels behave like sub-pixels of a normal
backlit display.

+ Reflective screen has reflector behind LCD grid.
+ Room light passes through grayscale LCD and bounces off of back
reflector.
+ 1200x900 pixels depending on ambient outside light to display.

+ The light the user sees comes from both sources (reflected outside
light plus filtered backlight).
+ Color filters use fresnel prisms to pass most light, instead of
color filters that absorb most light, wasting less energy.

+ The amount of color and perceived resolution depends on backlight
brightness and outside light level.
+ The ambient light level of the room changes the perceived
resolution of the display.
+ In direct sunlight you see the reflective screen (exactly 1200x900,
200 dpi),
+ In a dark room you see the backlit screen (approx. 800x600
perceived, 133 dpi),
+ In between you see both (approx. 1024x768 perceived).
+ The "official story" is "1200x900 mono resolution,
693x520 color resolution".

+ Screen layers:
+ LED backlight.
+ 1200x900 grid of color filters (fresnel prisms).
+ Semi-reflective layer.
+ 1200x900 LCD.
+ Each pixel has a single color behind it.
+ Colors are arranged in a diagonal pattern.
+ Each pixel has:
+ Fixed hue (r, g or b).
+ 6 bits (64 gray levels) of luminance.
+ Chrominance depends on relative strength of room light
to backlight.

+ DCON screen driver chip
+ The screen can stay on while the processor is turned off.
+ Automatically interpolates ("swizzles") lower resolution color
pixels, so the unusual screen format is invisible to software.
+ Looks just like a regular 1200x900 color framebuffer to software.
+ DCON has different modes:
+ Monochrome.
+ Color swizzled antialiased.
+ Color swizzled not antialiased.
+ Video pass through.

+ Power saving techniques
+ Uses low power LEDs instead of high voltage cold cathode
fluorescent backlights.
+ Turns off processor while leaving the screen and wireless
network on.
+ Uses fresnel prisms to split most white light into primary
colors, instead of color filters to throw away most light.
+ Turn down refresh rate.
+ Dynamically turn off sections of the screen.

+ Green Electronics

+ Order of magnitude less power consumption.
+ Designed to use as many environmentally friendly components
as possible.
+ Fully compliant with EU's Restriction of Hazardous Substances
Directive (RoHS).
+ One of eight laptops to receive EPEAT's Gold rating for
environmental performance.

+ GPS

+ A future version of the OLPC may include a built-in GPS!
+ The OLPC project needs GPS mapping sofware and low resolution
maps, which kids can improve, to map out the areas of the world
where they live.

+ Software

+ OpenFirmware Forth BIOS loader boot ROMs.
+ Pared-down version of Fedora Linux.
+ Custom web browser based on Gecko engine (xulrunner + Cairo) used
by Mozilla Firefox.
+ Word processor based on AbiWord. Paint program.
+ Email via web based services.
+ Online chat and VoIP programs.
+ Many programming languages:
+ Python, JavaScript, Forth, Csound, eToys (visual, Squeak
Smalltalk), Logo (visual), TamTam (visual).
+ Music sequences with digital instruments: Jean Piche's TamTam.
+ Audio and video players.
+ RSS news reader. Calculator.
+ Games: SimCity. Tetris. Connect. Others in development.
+ Educational software and content. Wikipedia.
Internet Archive. E-books. Scanned books. PDF files.

+ Python is the primary programming language for the "Sugar" user
interface and applications.

+ Important Python modules and libraries:
+ Sugar graphical user interface, written in Python, with GTK,
Cairo and Pango.
+ GTK user interface toolkit for X11.
+ Cairo rendering library (hardware accelerated Porter/Duff imaging
model, like PostScript).
+ Great for efficiently drawing high quality antialiased maps
with high quality scalable graphics and text, with hardware
acceleration.
+ Pango international text rendering library.
+ Pygame computer game programming module (graphics, audio,
input, etc).
+ Mozilla xulrunner (Firefox Gecko web browser component).
+ PyXPCOM Python/XPCOM integration module (enables Python and
JavaScript to script the browser, share objects and call each
other).
+ Many other high quality Python modules.

+ Project Status: October 2008
+ About half a million XO-1 units out in the field.
Most are in South America.
+ Afghanistan, Brazil, Cambodia, Columbia (65,000 ordered, 700
pilots), Ethiopia (5,000 shipped), Ghana, Haiti (7,000
shipped), India, Iraq (200 shipped), Mali, Mexico (50,000
ordered), Mongolia (10,000 shipped), Nepal, Nicaragua, Nigeria
(300 shipped), Niue (500 shipped), Oceania (5000 shipped),
Pakistan, Peru (260,000 ordered, 20,000 shipped), Philippines,
Rwanda (5,000 shipped), Tanzania, Thailand, USA (Alabama
(15,000 ordered), Massachusets, New York, Virgin Islands),
Uraguay (100,000 ordered, 10,000 shipped), Yemen.
+ You can buy an XO-1 on eBay now, for $90-$200.
+ G1G1 program ran last year.
+ G1G1 v2 program in America will be run by Amazon,
starts mid November.
+ A new G1G1 program has been announced for Europe, beginning on
November 17, the same day as the US program starts.
+ The price will be around $399, 312 EUR (no VAT will apply,
only shipping cost).
+ The 27 member states of the EU, plus Switzerland, Russia and
Turkey are included.
+ Where to get them: http://www.amazon.com/xo
+ More info about OLPC Foundation Europe: http://www.olpceu.org
+ Latest Changes
+ The new version of XO-1 has slight revisions to the circuit
board, changing a few things, because parts they are using
going obsolete. Trying not to change it much.
+ Making versions of XO-1 with more RAM and more flash memory.
+ Revamped basic sugar interface.
+ Software support for low power consumption is coming along.
+ New software release is going in the can this week.
+ Suspends when you close the laptop.
+ Turns off WiFi chip while in suspend unless actually on mesh.
+ Will sit in suspend for 2 days, which John timed.
+ User interface for power saving modes.
+ Sugar control panel, extreme power saving mode without WiFi,
saves a watt.
+ Advanced power management mode, goes into suspend when machine
is idle, leaves machine on, powers off CPU.
+ Still has a bunch of bugs around the edges:
+ Sharing over the net, presence service screws up sometimes,
but basically works.
+ Need to figure out how to decide whether a laptop is there
or not.
+ Multicast port, machine wakes up when it gets a multicast
it's interested in, but it always wakes up because protocol
does too much milticasting, busy protocol, otherwise the
world thinks laptop goes away.

+ The next version: XO-2
+ The X0-2 exists playdough mockup, looks like paperback with
2 hires multitouch screen, no keyboard.
+ No working hardware for that stuff.
+ Jim Gettys stopped working on other things, and is now working
on full blown multi touch support in X servers.
+ Price target is $75 for the XO-2, but that seems unlikely.

+ Mesh Networking Problems
+ Mesh networking stuff still does not work well.
+ Not using mesh networking in most schools, since it does not
scale to more than 10 laptops.
+ 30 laptops in room all on mesh melt down the network talking
to each other.
+ Can't reliably do TCP on a busy mesh network, because computers
are too busy doing status updates.
+ The problem is complicated with using multicast, which have to
get repeated throughout the mesh.
+ The idea of sticking laptops in a room and they see each other
is a good idea.
+ School servers should put up standard WiFi access points.
+ Mesh networking still useful if small deployment scattered
across whole village.
+ Don't use mesh networking for larger tasks than 10 or 15 laptops.
+ Could improve it with more work.
+ Work should go into getting colaboration protocols (independent
of mesh networking) out into generic Linux world.
+ AbiWord should be able to share across internet to edit the same
document.

+ Windows Compatibility
+ OpenFirmware boot ROMs are now compatible with Windows BIOS,
so it can boot Windows and Linux without reflashing.
+ OLPC is not doing any work on Windows, not shipping Windows.
+ Putting all work into Linux based stuff, everything they are
shipping is free software
+ OLPC will sell laptops to countries that want to run Windows.
+ Countries must worry about it.
+ You can't buy that version of Windows in developed countries.
+ $3 version of Windows not for sale in the US or anywhere people
pay full price for Windows, just the "third world".

+ High Expectations
+ OLPC had to recover from artificially high expectations created
by the fawning press and Nick Negroponte.
+ The high expectations had to come crashing down eventually.
+ The Windows announcement finally casued it to crash down.
+ Only a few hundred in pilot running Windows.
+ All the rest are running Fedora Linux.
+ The community needs to be reminded that OLPC is still a free
software project.
+ OLPC is the largest deployment of Fedore anywhere.
+ 500,000 units of Fedore, 50,000 more every month.

+ Successes
+ Two good things have happened to the project in the broader sense:

1) Spawned this whole netbook thing.
+ Nobody was doing that before.
+ Now 15 different major companies are doing the same thing.
+ Finally people are exploring the low cost low power end
of the laptop spectrum.
+ OLPC is still unique in that it was ruggedly designed to be
dropped and survive.
+ Other companies have not figured that out yet, and are still
making cheap low quality laptops.

2) The free software community is widely in favor of the project.
The deal with Microsoft got bad press, and most people in the
free software community mistakenly think the free software part
is over, and OLPC is now shipping laptops with Windows.
But actually they are not.