Vacuum tube systems in apollo era space missions
Start from this page and drool :-) 

http://klabs.org/history/build_agc/

Abstract of the page: 


  This report describes my successful
  project to build a working
  reproduction of the 1964 prototype for
  the Block I Apollo Guidance Computer.
  The AGC is the flight computer for the
  Apollo moon landings, with one unit in
  the command module and one in the LEM.
  
  I built it in my basement. It took me
  4 years.
  
  If you like, you can build one too. It
  will take you less time, and yours
  will be better than mine.