Some users may need specific support because of e.g. some visual impairment. Most 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.
The Debian installer supports several front-ends for asking questions, with
varying convenience for accessibility: notably,
uses plain text while
newt uses text-based dialog
boxes. The choice can be made at the boot prompt, see the documentation for
DEBIAN_FRONTEND in Section 5.3.2, “Debian Installer Parameters”.
newt front-end (used mostly with braille), one
mostly just selects answers with arrow keys and presses Enter to
validate the choice. Pressing Tab or Shift - Tab allows to
switch between dialog elements, and notably to access the
Go Back button, which brings back again to previous
questions. Some dialogs contain check boxes, which can be ticked on and off by
text front-end (used mostly with speech), one
mostly selects answers either by typing their number followed by pressing
Enter, or by selecting an answer with arrow keys, and pressing Enter
to validate the choice. One can also not type anything and just press
Enter to simply accept the default value. Typing
and pressing Enter brings back again to previous questions. When a
selection of choices has to be made (e.g. during task selection), one can type
! to express an empty selection.
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
boot parameter. This will however reduce the number of available languages.
For users with low vision, the installer can use a high-contrast
color theme that makes it more readable. To enable it, you can
use the “Accessible high contrast” entry from the boot screen with the
d shortcut, or append the
theme=dark boot parameter.
For users with low vision, the graphical installer has a very basic zoom support: the Control++ and Control+- shortcuts increase and decrease the font size.
Expert, Rescue, and Automated installation choices are also available
with accessibility support. To access them, one has to first enter the
“Advanced options” submenu from the boot menu by typing
a. When using a BIOS system (the boot menu will
have beeped only once), this has to be followed by Enter ;
for UEFI systems (the boot menu will have beeped twice) that must not be done. Then, to
enable speech synthesis,
s can optionally be pressed
(followed again by Enter on BIOS systems but not on UEFI systems). From there, various
shortcuts can be used:
x for expert installation,
r for rescue mode, or
automated installation. Again these need to be followed by Enter when
using a BIOS system.
The automated install choice allows to install Debian completely automatically by using preseeding, whose source can be entered after accessibility features get started. Preseeding itself is documented in Appendix B, Automating the installation using preseeding.
Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page.