Within every operating system available there is the potential to make adjustments to suit personal needs
Windows
Since the release of Windows95 there has always been an integrated set of accessibility features which you can configure through your "Control Panel". You can configure how the computer interacts with you. For example; if you only have the use of one hand, using a keyboard would be difficult, due to the amount of options which require you to press 2 keys at the same time. By loading "Sticky-Keys", within the Windows Accessibility Features, the computer can be changed so that it works one keystroke at a time. Other useful features include the ability to slow down the repeat speed of the keyboard and how long you have to hold a key down for, before it is processed.
Information on the features within each version of windows and other platforms can be found below:
Accessibility Options in Windows for Users with Physical Impairments