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.
When you receive a product donation, you can choose to download the current version of the software or the previous version. You can find out which version is the current one in the Microsoft Title Groups document. In addition, you can download the software in any language that's available.