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BrailleLite Display Table (six-dot cells only)


Upper rows: Basic Latin character corresponding to code
Lower rows: Braille cell corresponding to code


What is a Braille Display Table?

A Display Table is a Glyph Table, associating character codes with dot patterns, used by a display driver for converting from electronic input to tactile braille output. Many Tables are for eight-dot braille with six-dot braille simply being a subset. The Tables work in reverse when using an electronic braille keyboard to enter braille.

Braille Display Tables are built into various models of embossers and refreshable braille displays (RBDs). The Table shown above is for the BrailleLite manufactured now by Freedom Scientific and originally by Blazie. Of course, these displays that use eight-dot braille require more table entries than just the ones for the six-dot cells shown here.

Display Tables are not intended for direct use by humans but require a software interface or a driver to convert the input electronic braille to the format needed by the particular embosser or braille display. It is essential to use the proper driver in order to get the correct dots.

Drivers and Interfaces

The drivers for embossers are available from the manufacturers and interfaces for common models of embossers are also built into some braille transcribing programs.

The interfaces for RBDs are typically available with screen readers. Many braille readers have gotten disappointed with JAWS because of poor service from Freedom Scientific. Windows users are turning to WindowEyes. The WindowEyes screen reader interfaces to more than 40 different braille displays. Linux users use the free brltty virtual terminal which also supports a number of different displays. Both WindowEyes and brltty have built-in Grade 2 translators for instantaneous transcription of printed text to braille.

Reading Braille Files on a Braille Display

Braille displays with built in transcribing software have two modes: translate on and translate off. The same is true of screenreaders. The translate off mode is used for reading electronically distributed (pre-translated) braille since re-translating a translated file would obviously produce garbage. This mode is also used for reading braille that has been directly entered on the keyboard.

Even in translate off mode, it is still necessary to ensure that the Table used for representing the braille cells in the braille file is consistent with the Table being used by the display. The Display Table for the BrailleLite is designed so that the proper dots for six-dot braille will be displayed when reading a braille format BRF file that uses the ASCII Braille Table if

  1. Translate off is being used and
  2. Six-dot display mode is activated (display of dots seven and eight is turned off).
In fact, if you load a BRF file into a BrailleLite, the translate off option is automatically selected. I've heard that other models of displays work the same way but I don't know for sure. Custom braille files which contain a mixture of six-dot and eight-dot braille have to be treated on a case-by-case basis.

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This page was first posted November 30, 2002.

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