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.
1 The Microsoft Download Center. 2  The Malicious Software Removal Tool website on Microsoft.com. 3  The computer must be running Windows 7, Windows Vista, Windows Server 2003, or Windows XP. 4  You must log on to the computer by using an account that is a member of the Administrators group. The Microsoft Download Center. 2  The Malicious Software Removal Tool website on Microsoft.com. 3  The computer must be running Windows 7, Windows Vista, Windows Server 2003, or Windows XP. 4  You must log on to the computer by using an account that is a member of the Administrators group.