5.2. Accessibility 5.2.1. Installer front-end 5.2.2. Board Devices 5.2.3. High-Contrast Theme 5.2.4. Zoom 5.2.5. Preseeding 5.2.6. Accessibility of the installed system 5.3. Boot Parameters Boot parameters are Linux kernel parameters which are generally used to make sure that peripherals are dealt with properly. For the most part, the kernel can auto-detect information about your periph- erals. However, in some cases you’ll have to help the kernel a bit. Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page (http://wiki.debian.org/accessibility). Alternatively, Ubuntu can be installed completely automatically by using preseeding. This is docu- mented in Appendix B. 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. 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. 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. The Ubuntu installer supports several front-ends for asking questions, with varying convenience for accessibility: notably, text 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. 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. Chapter 5. Booting the Installation System 34