 New versions of the basic 1604 architecture were rebuilt into the CDC 3000 series, which sold through the early and mid-1960s.Cray immediately turned to the design of a machine that would be the fastest (or in the terminology of the day, largest) machine in the world, setting the goal at 50 times the speed of the 1604.This required radical changes in design, and as the project "dragged on" — it had gone on for about four years by then — the management got increasingly upset and it demanded greater oversight.