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.
The Debian 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 第 5.3.2 节 “Debian 安装程序的参数”.
系统应该可以自动检测到 USB 盲文点显器。然后自动选取安装程序的文本界面,该设备也会被自动安装到最终系统中。您只需要在引导菜单中按下 Enter 键。一旦 brltty
启动,您就可以通过菜单选择 braille table。在 brltty
website 可以找到盲文点显器的键绑定文档。
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
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.
一些辅助设备实际上是插入计算机里面的板卡,它们直接从显存里面读取字符。要让它们工作,需要使用引导参数 fb=false
禁止使用 framebuffer。然而这会减少可用语言的数量。
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.
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. Then, to enable speech synthesis, s
can optionally be pressed (followed again by Enter when using a BIOS system). From there, various shortcuts can be used: x
for expert installation, r
for rescue mode, or a
for automated installation. When using a BIOS system, they must be followed by Enter.
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 附录 B, 使用预置自动进行安装.
Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page.