1955: TRADIC - The First Fully Transistorized Computer
TRADIC stands for TRAnisitor DIgital Computer, and as the name suggests this was the first machine to use all transistors and diodes and no vacuum tubes. It was built by Bell Labs for the U.S. Air Force, which was interested in the lightweight nature of such a computer for airborne use. The machine consisted of 700 point-contact transistors and 10,000 germanium diodes. During two years of continuous operation only 17 of these devices failed, a vastly lower failure rate than Vacuum tube machines of the time.