Original Tinkertoy Computer

Object is an assembly of standard Tinkertoy rods and wheels in a 3x3 array of units (as seen from the front). There are a number of strings used as belts to connect rotating parts between units. In a letter from Danny Hillis to Gordon Bell dated May 21, 1981 : "It contains about 10,000 wooden parts, plus some fishing line and sinkers, all held together by small brass escutcheons. The machine plays tic-tac-toe with the human player giving the first move. It never loses. The game tree was generated by a LISP program running on a PDP-10. The PDP-10 also computed the connections of the 140 nine-input gates in the machine. The gates are all TTL (Tinker Toy Logic). A simple three-state logic is used to represent the three possible states of a square (X-O-blank). The design uses simple combinational logic. It could have been built by any six-year old with 500 boxes of tinker toys and a PDP-10. I designed the machine with Brian Silverman in 1978. It was purchased by the Arkansas Department of Parks and Tourism and placed in the Mid-America Museum. The machine works, but it's flaky. It requires constant tightening of the fishing line. The [Mid-America] museum wanted a more rugged machine that they demonstrate every day, so in 1980 we built a second machine... It works much better and has fewer parts, but I think it is a less impressive object."