To begin to answer your 'abstract question', "What are Silver Machines good for', one need only look at the title of Prof. Silver's unpublished manuscript

>"How to eliminate the fine structure from the work of jensen"

to find the beginning of the answer.


Why does one wish to eliminate the fine structure of Jensen?  For the reason given by Boris Piwinger in section 0 of his Diploma Thesis found by clicking on the link "Silver Machines" found in Prof. Golshani's answer (I am quoting from an English translation I found on the Web--on pp. 2-3 of the translation):

>The idea [of fine structure theory--my comment] is to have a closer look at the passage from $L_{\alpha}$ to $L_{\alpha + 1}$ and to describe the process with some "bookkeeping device".  Even today--after 25 years of development--, this method is extremely complicated and wearisome [is it really?--my question].


This is the correct context in which to frame the OP's question (at least in my opinion).