The local to me College of NJ library has copies of "How to design" by Heiserman and "How to build" by Loofbourrow. I read them and they are both interesting and useful as vintage how-to robotics books. Heiserman is pre-microprocessor so it's pure TTL digital logic. It's informative about digital methods. Loofbourrow covers a lot of mechanics on joints, hands; and has lots of KIM 6502 code. Both books, and others of that late 1970's era, are good on how to make mechanical stuff from available materials - wood, metal, etc. To make robotics from stuff on hand, not stuff you buy for that use. And they lay out the logic and often the code for managing sensors and actuators; stuff that's often buried in support code today. It's informative and educational to see these things at a fundamental level. HErb -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net