developing for blackberry 5/6

I am writing an java based application开发者_StackOverflow中文版 for blackberry. Can anyone please tell me if it makes any difference in running my app in old models of Blackberry or the latest version ?

If you use APIs that were introduced in 5.0, your application will NOT run on devices running an OS prior to 5.0 (i.e. the 83xx series Curve which are still quite popular - most are still running 4.3 or 4.5). Same goes for 6.0 - if you use any APIs new to 6.0 it will only run on devices running the 6.0 OS or higher (as of this time only one model, the Torch 9800).

See https://stackoverflow.com/questions/1437044/which-blackberry-os-version-to-target-for for more information about choosing the lowest OS version to support with your app. But it basically depends on how large of a market share you wish to reach with your application.