While I published everything you need to know about the upcoming Windows Phone update, codenamed "Tango," about a month ago in Windows Phone in 2012, there are those who won't believe anything about a Microsoft product until they confirm the information themselves. So with regards to Tango, they have now verified virtually everything I wrote.

In a post to the Windows Phone Developer blog, Microsoft's Mike Battista confirms that this next Windows Phone update, which will marketed as part of the Windows Phone 7.5 line as I first wrote last month, will open up the platform to new markets and lower-end devices. But you knew that.

"Apps that follow performance best practices today will run well across all devices without much effort," he writes in the post. "Apps that perform adequately today may perform noticeably slower on lower-cost devices."

Key takeaways from this post, which is of course aimed at developers, include the fact that Windows Phone apps should not exceed 90MB of memory usage on 256MB devices. A new version of the Windows Phone SDK, version 7.1.1, provides a low-end device emulator to help developers target these new types of Windows Phones.

Likewise, as I first reported in February, Windows Phone "Tango" doesn't just reduce the available RAM, it reduces the availability of other on-device resources too, including background agents.

In a previous post to the Windows Phone blog on February 27, Microsoft's Joe B. noted that this push to low-end phones would open up the platform to 23 new markets. He also confirmed my report that some existing apps would not run on Tango devices. 

"A small number (around 5%) of current applications will not run properly on the new lower cost devices," he wrote. Microsoft is working with the developers of these apps to see if they can be fixed. One of the "bad" apps, I'm told, is Plants vs. Zombies.