In addition to screen-reading software, some blind people also have a braille display attached to their computers. Though not strictly necessary to make the PC accessible, a braille display goes a long way toward achieving this goal.
Braille is written in cells. Each cell has six dots–three on the left and three on the right. With these six dots, you can braille everything in the English language and many other languages, punctuation, mathematical symbols, and more.
A braille display is a single line of 18, 20, 32, 40, or 80 Braille cells arranged in a single line. The Braille dots are made of plastic pins, and there is a cover over each cell to keep the pins in place. Software drivers power the display when it's connected to a PC, and the text that appears on the screen can be spoken by the screen-reading software and/or displayed in Braille. The display has advance bars called either thumb keys or whiz wheels, depending on the model, and these allow the reader to scroll backward and forward through the text on the screen.
Braille displays offer other functionality as well. Many of them have a cursor routing button over each cell. When one is pressed, the computer cursor moves to that point on the screen. In addition, they sometimes offer six keys that can be used as Braille keys. With these, a blind person who can write in Braille has the ability to enter text in Braille, instead of via the computer keyboard.
Braille displays offer enhanced editing capabilities that aren't available with screen-readers–which only provide spoken feedback. Transcriptionists, proof-readers, and editors, for instance, use their Braille displays to make sure punctuation and capitalization are correct, text is formatted properly, and that words are spelled correctly.
Two companies that manufacture Braille displays are Freedom Scientific and HumanWare. Freedom Scientific is the main retailer in the United States, but some also have HumanWare displays. Both companies offer displays for computers, but also personal note-takers, similar to PDAs, with Braille displays. These have small displays of 18, 20, or 32 cells. These devices are most often used by students and working professionals.
Unfortunately, Braille displays are extremely expensive. The least expensive is a 20-cell Focus Braille display made by Freedom Scientific, at a cost of $1200. The most expensive Braille display costs over $7000, and is an 80-cell display, also from Freedom Scientific.
People who have Braille displays say they do indeed provide more reliable feedback for blind computer users than speech synthesizers. However, most people still only have screen-reading software, but hopefully Braille displays will become more affordable in the future.