Amazon’s portable, handheld reader, which allows users to download digital versions of books, newspapers, and magazines, represents one of the first consumer uses of a low-power, easy-to-read electrophoretic display. The $399 device is a breeze to use, and though the company has not disclosed sales numbers, demand quickly outstripped supply. However, the success of the Kindle may depend on consumers’ willingness to bear the price of using it: though e-books, at $9.99, cost less than most physical books, newspapers, blogs, and other content available free on the Internet will cost money (for instance, $1.99 per month for Slashdot and $13.99 per month for the New York Times).

1. Electronic paper
The Kindle’s 600-by-800-pixel, 167-pixels-per-inch screen uses a display technology made by E Ink of Cambridge, MA. At the front of the screen is a layer of transparent electrodes. Below it are millions of microcapsules containing positively charged white particles and negatively charged black particles, and below them is a layer of nearly a million more electrodes. A negative charge on one of these bottom electrodes pushes black particles to the top, and a positive charge does the same with the white ones. Each microcapsule acts as a pixel that can thus be made to appear black, white, or gray.

E-paper consumes far less power than LCD displays do. Because the microcapsules retain their configurations until a new charge is applied, the display doesn’t have to draw current until it’s time to switch pages.

2. CPU
Powering the Kindle is an Intel PXA255 processor, says John Knuth, lead technician at Rapid Repair and one of the first to take apart the Kindle. This processor is part of Intel’s XScale line, designed for use in mobile phones and smart phones.

3. Wireless downloads
Most electronic readers require physical connection to a computer to retrieve data, but the Kindle allows users to browse and download texts wirelessly via what Amazon is calling Whispernet: an AnyData EVDO wireless modem enables the device to connect to Sprint’s wireless data network in the United States. In addition to buying books, users can subscribe to newspapers and blogs, which are downloaded automatically–each morning, in the case of daily papers. Though Amazon charges for this content (even when it’s available free on the Internet), a browser bundled with the Kindle allows users to read other Web content at no cost.

4. Operating system
Amazon decided that the Kindle would run a modified version of the Linux 2.6.10 kernel. One of the modifications added support for execute in place (XIP), which allows faster and more efficient memory usage. In compliance with Linux licensing, Amazon has made the modified source code freely available.

5. Memory
The Kindle comes with 256 megabytes of internal flash memory, 180 megabytes of which is available for storing content. (On average, that’s enough for about 200 books.) Users can also use SD cards for more storage. Though it’s more expensive than hard-drive-based storage, flash memory offers quicker access, lighter weight, and more resistance to bumps and shocks.

6. Battery
The Kindle uses a replaceable lithium-­polymer battery. Amazon claims that when the device’s wireless connectivity is switched off, users can read for a week on one battery charge.