Difference Between Old Bootrom and New Bootrom - An iOS Bootrom, known as “SecureROM” by Apple, is the most basic code that runs on an iOS device. It is read-only, meaning that you can’t write on it after it is installed. Each device version has its own Bootrom.
iOS jailbreaking is done by finding exploits in the Bootrom of that device. Once it is done, the rest of the stuff is pretty easy. Moreover, Apple can’t even fix that exploit without a hardware revision so exploiting the bootrom is a pretty big thing.
Difference Between Old Bootrom and New Bootrom
Only some devices have different bootrom versions like the iPhone 3GS and the iPod Touch 2G and are referred to as “new bootrom” and “old bootrom”.
The iPhone 3GS with the older bootrom had an exploit in it which got fixed in the newer bootrom which was released after 9 September 2009. Each model of the iPhone 3GS that got released after the 9th of September runs on the newer bootrom.
How To Find The Bootrom Version?
Finding the Bootrom version is very easy as it is included in the serial number and model number of your iPhone.
- Serial Number: If the second character of the model number of your iPhone 3GS is “B”, then it is uses the old bootrom. If it is “C”, then it runs on the newer bootrom.
- Model Number: The third digit of the serial number of your iPhone indicates the year it was released in (9 for 2009). While the fourth and fifth are dedicated to the week it was made in. Any iPhone made on or after Week 45 of 2009 runs on the new bootrom.
Jailbreaks for old and new bootrom also differ as the jailbreak software created with the old exploit can not work on the newer one.