If you are planning to jailbreak/unlock iPhone 3GS 4.0 then we sure you would have come across term like old bootrom/new bootrom. Many users don’t understand what does this old bootrom means and how to find which bootrom their iPhone 3GS has.
In order to help you to check your iPhone 3GS bootrom here is small utility “iDetector” developed by iH8sn0w. iDetector is a real easy to use application to tell wheter or not your iPhone 3G[S] contains the New Bootrom or the Old bootrom. Simply place your 3GS into DFU mode and click the button. iDetector only supports iPhone 3GS.