Linux
Far less commonly used than Windows or Apple computers, Linux is popular amongst technically-minded people but is not advised for a novice! There are a number of different versions of Linux (called "distros") available, with different accessibility features. The main screen reader under development is called Orca.
Orca has been included as part of the GNOME desktop since version 2.16 (September 2006) and is included in many distros including Fedora, Ubuntu, Mint, Debian and (optionally) openSUSE.
Orca comes with the Festival or eSpeak synthesisers, depending on which distro you have. Support for contracted braille is via the liblouis project which ships with many distros.
Earlier versions of Orca included a basic magnifier with options for foreground and background colours and the mouse pointer. The current version, 3.4.2, does not include magnification.
Vinux is a distro designed for blind or partially sighted users - it has a speech-enabled installation, full screen magnification and braille support, and it includes a lot of accessible applications.
The Speakup screen reader can be run on a number of Linux distros including Debian, Slackware and Fedora Core. It does not include a synthesiser, but works with a variety of free and commercial hardware or software synthesisers (e.g. eSpeak, Festival or Flite, which are all free, and Fonix DecTalk).
Emacspeak is a speech interface which uses "audio formatting" - variations in voice inflection and other characteristics together with non-speech sounds to convey information about layout and formats. Its latest release is Emacspeak 36.0 (EPubDog), and it supports IBM ViaVoice TTS and Fonix Software DecTalk software synthesisers as well as DecTalk hardware synthesisers.
Chrome OS
Laptops running Google's Chrome OS - Chromebooks - have been available in the UK since the summer of 2011. All applications are run through a browser interface, with a pop-up taskbar . Without an internet connection, therefore, you can do little with a Chromebook.
ChromeBooks have a non-standard keyboard with a Search key where most keyboards have a Caps Lock key. The top row of the keyboard holds a number of action-specific keys such as Previous Page, Reload Page and Increase Volume.
Speech output
There is a built-in screen reader called ChromeVox, which can be started at the login screen by pressing Ctrl+Alt+Z or from the Settings screen (click "Show advanced settings" and then check "Enable spoken feedback"). ChromeVox is basic but workable.
ChromeVox uses the Shift + Search combination as the ChromeVox modifier, so for instance, ChromeVox + RightArrow, which moves to and reads the next screen element, would mean holding down the Shift and Search keys and tapping the RightArrow.
Display options
It is possible to zoom a page with the keystrokes Ctrl+Plus/Minus. It is also possible to change the display from within the Settings area (click "Show advanced settings" and then look for "Font size" and "Page zoom". Further down the page is an "Enable high contrast mode" checkbox). The size and zoom settings do not affect the Address bar or Settings menu.
It is possible to change screen colours with a theme or extension from the Chrome Web Store. A theme is a preset colour scheme and an extension adds or changes Chrome's functionality. The Extension category on the Chrome Web Store has an "Accessibility" sub-category which contains a number of potentially useful extensions.