High Quality Content by WIKIPEDIA articles! The CDC 3000 series computers from Control Data Corporation were mid-1960s follow-ons to the CDC 1604 and CDC 924 systems. Over time, a range of machines were produced - divided into the `upper 3000 series` and the `lower 3000 series`. CDC phased out production of the 3000 series in the early 1970s. The 3000 series were the `cash cows` of Control Data during the 1960s; sales of these machines funded the company while the 6000 series was designed.