Technical Talk

Amazon's first offering of Kindle in November 2007 sold out in five and a half hours and the device remained out of stock for five months until late April 2008.

The original Kindle device, featuring a 6 inch (diagonal) 4-level grayscale display, retailed for US$399. Amazon subsequently lowered the price to $359. The 250 MB of internal memory in the Amazon Kindle 1 can hold approximately 200 non-illustrated titles, and the memory is expandable with an SD memory card.This model is no longer available, as it was replaced by the Kindle 2.

On the original Kindle, Whispernet only works in the United States, but content can be downloaded from Amazon over the Internet. Amazon did not sell the original Kindle outside the United States. Plans for a launch in the UK and other European countries were delayed by problems with signing up suitable wireless network operators.

On February 9, 2009, Amazon announced the Kindle 2 which became available for purchase on February 23, 2009. The Kindle 2 features 16-level grayscale display, improved battery life, 20 percent faster page-refreshing, a text-to-speech option to read the text aloud, and overall thickness reduced from 0.8 to 0.36 inches (9.1 mm).

The Kindle 2 has 2 GB of internal memory of which 1.4 GB is user-accessible. Amazon estimates that the Kindle 2 will hold about 1500 non-illustrated books. Unlike the original Kindle, Kindle 2 does not have a slot for SD memory cards. To promote the new Kindle, author Stephen King made UR, his then-new novella, available exclusively through the Kindle Store. On October 22, 2009, Amazon ceased selling the Kindle 2 as originally built in favor of the International Version it had introduced earlier in the month.

According to an early review by iFixit, the Kindle 2 features a Freescale 532 MHz, ARM-11 90 nm processor, 32MB main memory, 2 GB moviNAND Flash Storage, and a 3.7 V 1530 mAh lithium polymer battery. On November 24, 2009, Amazon released a firmware update for the Kindle 2 that it said increases battery life by 85% and introduces native PDF support.

On October 7, 2009, Amazon announced an international version of the Kindle 2 that works in over 100 countries, which became available October 19, 2009. The international Kindle 2 is physically very similar to the U.S.-only model although it uses a different mobile network standard. The original Kindle 2 uses the Sprint network while the international version uses AT&T's U.S. mobile network and roams on 3G, EDGE, and GPRS on GSM networks in other countries. On October 22, Amazon lowered the price on the international version to $259 from $279 and ceased selling the U.S.-only model.

On May 6, 2009, Amazon announced the Kindle DX which retails for $489. It is the first Kindle model with an accelerometer, automatically rotating pages between landscape and portrait orientations if the device is turned on its side, unless automatic rotation is disabled by the user. It is slightly over ¹⁄₃ inch (about 8.5 mm) thick, has a 4 GB (3.3 GB user-accessible) storage capacity, holding approximately 3500 non-illustrated e-books, a 9.7 inch (24.6 cm) display with 1200 x 824 pixel resolution, and a battery life of up to one week while using wireless or two weeks offline. The DX adds support for PDF files natively, built-in stereo speakers, and 1xRTT wireless technology as fallback option for when EVDO connectivity is not available. Like the Kindle 2, it does not have an SD memory card slot. The model was released on June 10, 2009.

The exact sales numbers were not released by the company, but according to some estimates based on official statements it is estimated that as of Q4-2009 there were about 1.5 million devices sold^.

Amazon e-book sales overtook print for the first time on Christmas Day of 2009.

Users can download content from Amazon and some other Kindle content providers in the proprietary Kindle format (AZW), or load content in various formats from a computer by simply emailing DOC, TXT, and PDF files to your own Kindle email address. Kindle Terms of Use forbid transferring Amazon e-books to another user or a different type of device^. Users can select reading material using the Kindle itself or through a computer at the Amazon Kindle store, and can download content through the Kindle Store, which upon the initial launch of the Kindle had more than 88,000 digital titles available for download, steadily increasing to more than 275,000 by late 2008. As of July 1, 2009, there were more than 300,000 books available for download. In late 2007, new releases and New York Times bestsellers are being offered for approximately US$10, with first chapters of many books offered as free samples. Many titles, including some classics, are offered free of charge or at a low price, which has been stated to relate to the cost of adapting the book to the Kindle format. Magazines, newspapers, and blogs via RSS such as popular blogs (Amazon Daily, Huffington Post, and Kindle me elmo) are provided by Amazon per a monthly subscription fee or a free trial period. Newspaper subscriptions cost from US$5.99 to $14.99 per month, magazines charge between $1.25 and $10.99 per month, and blogs charge from $0.99 to $1.99 per month.

The device is sold with electronic editions of its owner's manual and the New Oxford American Dictionary. Owners cannot use a dictionary in a language other than English as the "default lookup dictionary." The Kindle also contains several free experimental features, including a basic web browser. Users can also play music from MP3 files in the background in the order in which they were added to the Kindle. Operating system updates are designed to be received wirelessly and install automatically during a period in sleep mode in which wireless is turned on^.

The original Kindle supported only unprotected Mobipocket books (MOBI, PRC), plain text files (TXT), topaz format books (.tpz), and Amazon's proprietary DRM-restricted format (AZW). Version 2.3 firmware upgrade for Kindle 2 (U.S. and International) added native PDF support. Earlier versions did not fully support Portable Document Format (PDF), but Amazon provided "experimental" conversion to the native AZW format, with the caveat that not all PDFs may format correctly. It does not support the EPUB ebook standard. Amazon offers an email-based service that will convert JPEG, GIF, PNG, and BMP graphics to AZW. Amazon will also convert HTML pages and Microsoft Word (DOC) documents through the same email-based mechanism, which will send a Kindle-formatted file to the device directly for $0.15 per MB or to a personal e-mail account for free. These services can be accessed by sending emails to @kindle.com and to @free.kindle.com for Whispernet-delivered and free email-delivered file conversion, respectively. The file that the user wants to be converted needs to be attached to these emails. Users could also convert PDF and other files to the first-generation Kindle's supported formats using third-party software. The original Kindle supported audio in the form of MP3s and Audible audiobooks (versions 2, 3 and 4), which had to be transferred to the Kindle via USB or on an SD card.

Initially, Kindle 1 only supported the ISO 8859-1 (Latin 1) character set for its content; Unicode characters and non-Western characters were not supported. A firmware update in February 2009 added support for additional character sets, including ISO 8859-16.

Kindle 2 added support for Audible Enhanced (AAX) format, but dropped support for Audible versions 2 and 3. Using the experimental web browser, it was possible to download books directly on the Kindle (in MOBI, PRC and TXT formats only). Hyperlinks in a Mobipocket file could be used to download e-books but could not be used to reference books stored in the Kindle's memory. Kindle DX added native support for PDF files.

Users can bookmark, highlight, and look up content. Pages can be dog-eared for reference and notes can be added to relevant content. While a book is open on the display, menu options allow users to search for synonyms and definitions from the built-in dictionary. The device also remembers the last page read for each book. Pages can be saved as a "clipping", or a text file containing the text of the currently displayed page. All clippings are appended to a single file, which can be downloaded over a USB cable.