There are two way to check.first is you can directly check whether key contain A or not in binding like this:-. but i think this is not the better way so instead of this you can use ko.computed to check.
Check for operating system information in Windows 7. 1  Click the Start button , enter Computer in the search box, right-click Computer, and then click Properties. 2  Look under Windows edition for the version and edition of Windows that your PC is running.
Ciaran Griffin/Stockbyte/Getty Images. Click the Version tab if you are running Windows XP or the Details tab in Windows Vista and 7. The version of the Remote Desktop client installed on your computer is shown next to File Version in Windows XP or Product Version in Windows Vista and 7.The version number will be long--for example, 6.1.7600.16385.ips & Warnings. 1  If you are running Windows XP and your installed version of Remote Desktop begins with 5, the Terminal Services Client will be upgraded automatically if you install Service Pack 3 for Windows XP. 2  Alternatively, download the updated client from the link in the References section below.