IBM 7302

The IBM 7302 Core Storage unit was designed in 1957–1958 for the IBM 7030 (Stretch). The IBM 7030 could use from one to sixteen IBM 7302s (typically six); either individually or in interleaved groups of two or four. The IBM 7090 also used one IBM 7302. The IBM 7094 used one IBM 7302A. The IBM 7094 II used one IBM 7302, but it was a new model unique to the IBM 7094 II. The IBM 7080 also used one decimal model IBM 7302 with a different core stack than used in the binary models.
The core memory in the IBM 7302 was heated/cooled to stabilize its operating characteristics. Early units immersed the core stack in heated/cooled oil. Later units, called the IBM 7302A, blew heated/cooled air through the core stack. The use of smaller cores in the IBM 7302A allowed the cycle time to be reduced to 2.0μs for the IBM 7094. The use of even smaller cores in the IBM 7302 Model 3 allowed the cycle time to be reduced to 1.4μs for the IBM 7094 II.