Sony Corporation's Data Discman Electronic Book Player was first introduced to the Japanese market during the summer of 1990 and in the US in Sept 1991. The US price was $550.
The Data Discman uses a postcard-sized player for reading books recorded on 3.15-inch compact disks. Each disk can store approximately 100,000 pages of text or 32,000 graphic images. The unit has an LCD display of 30 characters by 10 lines, and a 26-character keyboard. Data on the electronic books can be searched by entering the first or last few letters of a search word, by entering key words, by menu, or by using an icon-based selection.
There were 18 models for this device with various screen sizes. Some models included a backlight. Some models had video output to support a larger screen. There were also variations depending on which books came with it. The last model was the DD-1EX which had a 3.5 inch (2.5x2inch) screen.
The electronic books to be played on the Data Discman were primarily reference books and most versions included Compton's Concise Encyclopedia, Wellness Encyclopedia, and Passport's World Travel Translator. A movie guide, a disk of baseball information, a year-in-review volume from the newspaper USA Today, international wine guide, Kings James Bible, Chambers Science and Technology Library and Hutchinson Gallup's Info were also available for purchase. The disks sold for $20 to $50. A complete Airline guide was available for $150 a year subscription.
- Screen Size: 3.5", 4", or 4.4"
- Resolution: 32 characters by 10 lines. On line was devoted to a function menu. A few models had 12 lines.
- The various models were different physical sizes but were approximately 160 mm long, 30 to 40 mm deep, and 107 to 113 mm wide.
- Weight: 1.5 lbs.
- Some models could play audio disks. DD-10EX.
 For more information
http://www.data-discman.info/ - Software to make CD's.
http://www.data-discman.info/ddmodels.htm - Model comparison
http://www.treebook.de/ - A German site still makes books for this device.