title: Short explanation of last two chapters of SICP
body: <p>Can anybody give me a clear and concise explanation of the last 2 chapters of SICP(structure and interpretation of computer programs), ch4 meta-linguistic abstraction and ch5 computing with register machines?</p>
  
  <p>I'd also like to know if(and how) these two chapters differ in content from a standard undergraduate compiler course.</p>