Some users may need specific support because of e.g. some visual impairment. USB braille displays are detected automatically, but most other accessibility features have to be enabled manually. On machines that support it, the boot menu emits a beep when it is ready to receive keystrokes. Some boot parameters can then be appended to enable accessibility features. Note that on most architectures the boot loader interprets your keyboard as a QWERTY keyboard.
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.
Serial braille displays cannot safely be automatically detected
(since that may damage some of them). You thus need to append the
brltty=
boot parameter to tell driver,port,tablebrltty which driver it
should use. driver should be replaced by the
two-letter driver code for your terminal (see the
driver code list).
port should be replaced by the name of the
serial port the display is connected to, ttyS0 is
the default. table is the name of the braille
table to be used (see the table code
list); 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.
Support for hardware speech synthesis devices is available only alongside support for graphical installer. You thus need to select the “Graphical install” entry in the boot menu.
Hardware speech synthesis devices cannot be automatically detected. You
thus need to append the
speakup.synth=
boot parameter to tell driverspeakup which driver it should
use. driver should be replaced by the driver code
for your device (see driver code
list). The textual version of the installer will then be
automatically selected, and support for the speech synthesis device will be
automatically installed on the target system.
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
vga=normal fb=false
boot parameter. This will however reduce the number of available languages.
If desired a textual version of the bootloader can be activated before adding
the boot parameter by typing h Enter.