5.2. Accessibility
| Chapter 5. Booting the Installation System |

## 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. Installer front-end

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, “Ubuntu Installer Parameters”.

### 5.2.2. 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.

### 5.2.3. 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`` boot parameter to tell `brltty` which driver and port 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. A third parameter can be provided, to choose 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. A fourth parameter can be provided to pass parameters to the braille driver, such as `protocol=foo` which is needed for some rare models. Documentation on key bindings for braille devices is available on the `brltty` website.

### 5.2.4. 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.

### 5.2.5. 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.

### 5.2.6. Zoom

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.

### 5.2.7. Preseeding

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

### 5.2.8. Accessibility of the installed system

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

5.1. Booting the Installer on PowerPC |  | 5.3. Boot Parameters