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 Download the Microsoft Security Essentials virus and spyware definition update file that is appropriate for your version of Windows: 2  Note You must be running a 64-bit version of Windows to run a 64-bit version of Microsoft Security Essentials.3  The 64-bit versions of Windows include x64-based versions of Windows. To install the saved file, follow these steps: 2  Windows XP. 3  Double-click the file, and then click OK. 4  Windows Vista or Windows 7. 5  Right-click the file, and then click Run As Administrator.