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.