The personal computer needs the optically-size-reduced IC chip developed for missiles in the sixties. If nobody thinks of it, parts of technology freeze. The best example I can compare it to is CPR, cardiopulmonary resuscitation, the first aid procedure. It was put in place in 1958. There is no reason it couldn't have been implemented in the 19th century, as it requires no instruments or medication. Nobody thought of it, plain and simple. In an earlier post, I mentioned a brief war in 1960 that ends the Cold War, takes away the need for ICBM missiles and stops the race to the moon. Some space flights will still happen. Weather satellites, when initiated, used transistors. In the late sixties, televisions with "works in a drawer" used solid state electronics for every component except the picture tube. That was progress that exceeded the expectations of WW2 veterans who endured the Depression and wartime rationing. In the mainframe years, learning about computers meant learning FORTRAN or COBOL, issues that took more training than the average person wanted to pursue.
