5.2. Accessibility

Some users may need specific support because of e.g. some visual impairment. USB braille displays are detected automatically (not serial displays connected via a serial-to-USB converter), but most other accessibility features have to be enabled manually. Some boot parameters can be appended to enable accessibility features. Note that on most architectures the boot loader interprets your keyboard as a QWERTY keyboard.

5.2.1. USB Braille Displays

USB braille displays should be automatically detected. A textual version of the installer will then be automatically selected, and support for the braille display will be automatically installed on the target system. You can thus just press Enter at the boot menu. Once brltty is started, you can choose a braille table by entering the preference menu. Documentation on key bindings for braille devices is available on the brltty website.

5.2.2. Serial Braille Displays

Serial braille displays cannot safely be automatically detected (since that may damage some of them). You thus need to append the brltty=driver,port,table boot parameter to tell brltty which driver it should use. driver should be replaced by the two-letter driver code for your terminal (see the BRLTTY manual). port should be replaced by the name of the serial port the display is connected to, ttyS0 is the default, ttyUSB0 can be typically used when using a serial-to-USB converter. table is the name of the braille table to be used (see the BRLTTY manual); the English table is the default. Note that the table can be changed later by entering the preference menu. Documentation on key bindings for braille devices is available on the brltty website.

5.2.3. Board Devices

Some accessibility devices are actual boards that are plugged inside the machine and that read text directly from the video memory. To get them to work framebuffer support must be disabled by using the fb=false boot parameter. This will however reduce the number of available languages.

5.2.4. High-Contrast Theme

For users with low vision, the installer can use a high-contrast color theme that makes it more readable. To enable it, append the theme=dark boot parameter.

5.2.5. Preseeding

Alternatively, Debian can be installed completely automatically by using preseeding. This is documented in Appendix B, Automating the installation using preseeding.

5.2.6. Accessibility of the installed system

Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page.