Choosing a computer, laptop or tablet can be a confusing process.
This guide aims to demystify some of the jargon and help you make an informed choice.
Let's start by explaining some common terms used by retailers to describe their products.
Processor speed: The speed that a computer can process information, measured in Gigahertz (Ghz). Typically at least 2.5 Ghz.
Random Access Memory (RAM): The working memory of a computer, measured in gigabytes (GB) and typically between 4GB and 12GB.
Disk Storage: The amount of space a machine has for storing data, measured in gigabytes (GB) and typically between 500GB and 1000GB (or 1 terabyte, 1TB).
Contrast ratio: A measure of the ability of a monitor (screen) to display colour contrast. Partially sighted people may find high contrast displays helpful.
Operating system: The software your computer runs on. The two most common for desktop and laptop computers are Microsoft Windows and Mac OS X; for tablets it's Android and iOS.
The latest version of Microsoft Windows operating system is Windows 8.1, which comes with a basic screen magnifier and screen reader. Various free and paid-for screen readers and screen magnifiers are available from third parties.
The latest version of the Mac OS X operating system is called Mavericks, which comes with a basic screen magnifier and fully fledged screen reader. Mac computers are considerably more expensive than Windows computers.
For everyday tasks like browsing the web, using email, watching films, playing music and creating documents, a standard machine should be adequate. More sophisticated tasks such as video and audio editing or playing some computer games may need a more powerful computer.
If you're going to use a screen reader, screen magnifier or other assistive technology, you may want additional RAM.
There are a range of different computers, laptops, and tablets available from manufacturers like HP, Lenovo, Dell, Acer and Apple.
The most popular computers in use today are desktops and laptops.
A desktop computer sits on a desktop or workstation, and is therefore not portable. A typical system consists of a monitor (or 'screen' or 'LCD display'), base unit (or a 'central processing unit'), keyboard and mouse or trackpad.
Desktops may be particularly valuable to people with low vision, as they come with a 20 inch or larger monitor. They also have a large number of ports for connecting equipment like printers, scanners and braille embossers.
A desktop package with a 23 inch LCD display, fast processor, 4GB of RAM and 500GB of storage, may cost between £350 and £700.
All-in-one computers are desktops with the processor, memory and all other components built onto the back of the display. Screen sizes range from 20 to 27 inches. All-in-ones are ideal if space is at a premium, but are more expensive and less easy to modify than desktop computers.
A laptop is a portable computer with processor, keyboard, battery and tilting display all incorporated into one. Also known as notebooks, laptops have become very popular as they can be easily carried. Available in all sizes and colours, laptops typically include a suite of built in accessories including microphone, web camera, Wi-Fi and Bluetooth. Lighter laptops will be more expensive than heavier models.
Netbooks are small, light and cheap laptops, typically costing £200 to £300. They usually have a 10 inch display, compact keyboard and very few connectors, but are good low-cost options for everyday computing. Almost all models include built-in webcam, microphone, Wi-Fi and Bluetooth. Older netbooks run Windows 7 Starter which has a limited version of the built-in screen magnifier.
Netbooks were very popular for a few years, but have become much less popular with the rise of tablet computers (see below).
Ultrabooks are high-end light laptops, usually costing £750 or above. While they can be powerful, their smaller size means they have a limited number of ports for connecting external devices.
A tablet is a small, thin and lightweight portable computer with a touch-screen, no keyboard and few physical buttons. The launch of the iPad in 2010 was the beginning of a huge surge of interest in tablet computing. While the iPad is still the most popular tablet on the market, there are new models becoming available every week.
Screen sizes range from 5-10 inches, and many tablets have two versions which differ in their screen size.
Typing is done on an on-screen keyboard which appears when it's needed, and disappears when typing isn't an option. Some people with sight loss can find the touch-screen challenging, as the lack of a tactile keyboard can present a real barrier. Some choose to use their tablet with a braille display or Bluetooth keyboard.
Tablets do have some distinct advantages over traditional technology. They are low weight with no moving parts, and are therefore more durable. They instantly 'wake up' so you can use them immediately, without having to wait for them to start up. Many have a rechargeable battery that lasts up to 10 hours.
Tablets work using wireless internet or Wi-Fi, so they are good to use on the move. Some also offer 3G, allowing you to access mobile phone networks (subject to subscription with a provider).
Tablets have far less storage than desktop or laptop computers, ranging from 8GB to 128GB. The assumption is that you will use online storage if you need more.
The iPad was the first tablet with built-in screen magnification and screen-reading capability that is accessible 'out of the box' (without setup), making them a good option for low vision users. When using the new iPad for the first time, simply click the 'home' button three times and the device begins talking straight away.
There is a built-in magnification feature called Zoom, as well as a facility to enlarge fonts in some apps. There is a invert colours feature, plus a range of other accessibility features.
iPads costs from £319 and are available from major high street retailers and Apple stores, and online from Apple and others.
There are lots of Android tablets on the market. The latest versions of Android, KitKat and Jelly Bean, contain a robust screen reader which can be started without sighted help, and a basic magnification facility that does require sighted assistance to start up. However, many manufacturers of Android tablets tinker with the facilities within Android, and this can have an impact on the accessibility.
The Nexus tablets have a version of Android that has not been tampered with or added to.
The Nexus costs from £199 and is available from a range of high street and online shops, including Google.
Windows RT is a version of Windows 8 designed especially for tablets. It has the same basic magnifier and screen reader as Windows 8, but is restricted to loading Windows Store apps. This means you cannot add another magnifier or screen reader.
Other Windows tablets run Windows 8 or Windows 8 Pro, both of which allow you to install other screen readers and magnifiers.
Windows 8 tablets cost from around £280 from many shops and online, for instance from Microsoft.
The web is a huge resource for finding out about technology, although of course you have to be able to use technology to use the web! Here are some examples of websites that contain useful information, most of which can be downloaded.
The Access Technology Institute offer training on Windows and Office with JAWS, Window-Eyes or NVDA.
VIP Software Guides has some useful Windows guides for users of screen magnifiers or JAWS.
AppleVis is a very popular community website for all things Apple.
Vision Australia have some great resources on their "Help Yourself!" page. Most of their audio downloads are aimed at users of Apple technology.
The makers of assistive technology may include guidance material in the box of goodies they sell you, or online. While aimed at users of their products, some may be useful even if you use a different product. Examples are the Freedom Scientific training page, GW Micro's audio video archive and the videos from the Dolphin Training Academy.