Microsoft is busy preparing a second update to Windows 8.1, but the company is largely focused on a larger “Windows 9″ release due next year. ZDNet reports that a preview of codename Threshold — which may or may not be named Windows 9 once it’s released — will be available later this year. The public preview is said to arrive in the fall, shortly after Windows 8.1 Update 2 is delivered to existing machines. Microsoft had been planning to bring the Start Menu back with Update 2, but the company is now planning to deliver that change with Threshold. While Microsoft has started to move away from the Start Screen for desktop PCs with Windows 8.1 Update, it appears that it will go further in the “Windows 9″ release. Sources familiar with Microsoft’s plans tell The Verge that the company is testing versions of Windows that enable the Start Menu by default on desktop machines, and hide the existing Start Screen from use.