BlackBerry on Wednesday published software development kit BlackBerry 10.3 beta for developers to test applications on the OS ahead of its launch. The update is targeted only for new device hardware being introduced later this year. The SDK is available to download via BlackBerry's developer site.

While inviting developers for testing, the company noted that it has delivered 'a variety of new features and tooling improvements' in the BlackBerry 10.3 SDK beta. Developers will see some visual changes and new functionality been introduced. Also, the SDK simulator (download) will show a square screen. BlackBerry says that it is for 'a new device with a 1440x1440 resolution and pixel density of 453 DPI,' which if one calculates, would indicate a display with a diagonal length of 4.5 inches.

If you dig through the details of the 10.3 SDK, you’ll notice that there is support for the screen resolutions we’re all used to: 1:1 and 16:9, with a dpi of 720×720 and 1280×720, respectively. In addition to that, there’s a simulator for a 1:1 ratio device with a resolution of 1440×1440. Naturally, BlackBerry gave no other details on what that device might be. In a blog post this afternoon, the folks over at BlackBerry DevBlog let developers know that the SDK for OS 10.3  is now available. The blog post has some pretty interesting information in it, including a pretty nice little confirmation about the anticipated BlackBerry Classic, as well as our first bit of news on OS 10.3.1.