One of the most impressive computer systems ever was the vacuum tube based behemoth AN/FSQ-7, which was the heart of the 'Semi Automatic Ground Environment'. Machines of this type were children of the Cold War and had a tremendous effect in politics. They also generated a vast amount of spin-offs which still shape our world. This book focuses on the technological achievements and details of this marvelous machine and of its predecessor Whirlwind. The various developments, ranging from magnetic core memory to data transmission via telephone lines, are covered in detail with schematics, circuit descriptions and small programming examples. This book is a treasure trove for those interested in the technology of early digital computers and those interested in the impact these machines had and still have on our current computer systems.