It's baked into the VM. When they say that in Smalltalk, everything's an object, they're seriously not kidding. Everything is an object, including compiled cod

It's baked into the VM. When they say that in Smalltalk, everything's an object, they're seriously not kidding. Everything is an object, including compiled code, stack frames, execution contexts, threads, etc. A traditional Smalltalk system uses an object table, where all object pointers are really references to a slot in the table; this allows the garbage collector to move objects around in memory easily. This means that it becomes trivial to dump everything out to disk, reload it later, update the object table, and suddenly the entire state of your system is restored (ignoring host OS resources, of course, but traditionally Smalltalk didn't use an operating system). I did have a handy sample for GNU Smalltalk that would snapshot an image containing a running thread which, when the thread was reloaded, would seamlessly resume but, er, I seem to have lost it.