IBM System/360

An IBM System/360 Model 30 at the Computer History Museum, its red cabinet beside the console panel of lights and switches. IBM announced System/360 in 1964 as one family rather than a set of unrelated machines: five models spanning a 50-to-1 range in performance, all able to run the same software. A customer could start small and move up without rewriting every program, an idea now so normal it is hard to see how radical it was. IBM's initial investment was $5 billion, and within two years orders were reaching 1,000 a month.