Root method of Squeak Image?

Hi.

I want to modify Squeak VM to only takes in string(Smalltalk expression), and return result in string. I have a look at embedded squeak, and it seems to be the answer. I want to make it even more simple. Maybe activate GC only with command; stop all the background process, only run with Smalltalk expression given.

Seems like I need to break the interpreter loop to do so, I mean return result from interp(), then interp() will be call for the next squeak expression. Any suggestion what should I do, or which part should I explore to make it possible?

I wish to know what exactly are those background processes, when no user input given. In squeak image, is there any method that acts like a main function in C? What I mean is, when method send returns to the previous method body, from one MethodContext back to the previous, we probably will reach the root. Is there any root method in image that taking care of GC, Scheduler etc.? Is it within object "proc"?

Thank you so much in advance for suggestion and answers.

Ang Beepeng