There are an increasing number of free assistive technology options for a computer.
These will be less sophisticated and have fewer features than software you can buy, but if you want to surf the web, send and receive emails, and write basic documents, one of these might be just the ticket.
Commercial magnifiers offer many features that you won't find in a free option, like the ability to magnify the screen before logging on. The free options are aimed at people who need only a relatively low level of magnification and mainly use the mouse.
The free applications often have no installation process or they have an installation process that does not require administrator privileges. This means they can be easily used on a public computer, or even run from a pen drive plugged into a computer. You should always check with the owner of a computer before doing this!
One of the restrictions of Windows Magnifier is that it has no full screen mode before Windows 7, and only in Windows 8 does it work with all colour settings.
The big plus of Lightning Express is that it gives full screen magnification. It works with 32-bit versions of Windows XP, Vista and 7, and with desktop apps in Windows 8.
A significant limitation of Lightning Express is that it has to be downloaded or run from the Internet each day.
Desktop Zoom works with Windows XP, 2000, Vista and 7. It has keyboard control for many of its options, which include mouse pointer size and shape enhancements, and speech output using the Windows voice. There are also some unusual features, such as the ability to turn off by moving the mouse pointer to the bottom right corner of the screen.
Desktop Zoom isn't as reliable as Magnifier or Lightning Express. Keyboard tracking and text smoothing don't work smoothly and zoom level settings are difficult to set. At high levels of magnification, smoothing and general movement deteriorate.
There are a number of free magnifiers that only magnify an area around the mouse pointer. They are usually aimed at people who need to do detailed graphics work and do not track the keyboard.
There are a number of free text-to-speech applications which can read out emails or documents. They will leave out lots of visual information such as if text is bolded or an email has an attachment, and are therefore not very useful if you need to use a computer but can't see the screen. Software that reads out this additional information is called a screen reader, and that is what this section covers.
NVDA (Non-Visual Desktop Access) is the most popular free screen reader. It is an open-source programme that comes in portable and installer versions - the portable version can be run from a pen drive without any installation.
NVDA uses the eSpeak synthesizer which includes UK regional accents. It works on Windows XP, Vista, 7 and 8, where it supports touch screens. It also supports ARIA-enabled web pages.
NVDA has support for the basic features of Windows, Internet Explorer and Mozilla Firefox, and a growing support for Microsoft Office.
GW Micro, the makers of the Window-Eyes screen reader, have released a free version for users of Microsoft Office 2010 and above.
The free version is the same as the paid-for version of Window-Eyes except that it does not include the same voices, has no print, braille or audio CD documentation, and comes with little free technical support.
This offer only started in January 2014, so it's too early to say how popular it will be.
There are other, less widely used, free screen readers:
System Access to Go works on Windows XP and later (although support on Windows 8 is restricted to desktop apps), and includes support for some braille displays and even basic screen magnification. You have to connect to the website to download and start it. It is a free version of the System Access screen reader, intended for use only in temporary situations.
The voices used by free screen readers may not appeal at first, as they can seem quite robotic. Voices may grow on you, or they may have other benefits such as responsiveness or staying understandable at high speech rates.
If you want to explore other voices, Microsoft's Speech Platform and voices are free, or you can buy more human-sounding voices from any vendor of commercial screen readers.
One way to get the Microsoft voices is via the GW Micro website:
Go to gwmicro.com/voices
Find the heading "Microsoft Speech Platform Downloads" at the bottom of the page and read the instructions.
In the combo box used to select a voice, the English voices start with "en".
Eldy is aimed at people aged over 60 or who are new to computing. It presents large, clear controls to allow writing of documents and email, sharing pictures and surfing the web. It may be of use to a partially sighted person interested in basic computer use.
Eldy is available for Windows, Mac and Linux computers, and some Android tablets. It contains simple instructions and video tutorials to help you get started.