There are only minor changes in the API between Simics version 3.0 and 2.2. Some functions that have been marked deprecated for a long time were removed.
The Simics API was changed for the 2.0 release to allow modeling of heterogeneous target systems, i.e., systems that have processors of different architectures all running in the same Simics session.
Modules written for the 1.4 and 1.6 versions of Simics can usually be compiled for Simics 2.0, using the obsolete API backward compatibility layer. Modules for version 1.8 should compile without any major changes, but in all those cases, there may be some minor updates that have to be done manually.
Modules from older versions has to specify what API that are written for by setting the make variable SIMICS_API. This variable can have one of the following values: