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In page Magnetic-core memory:

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Using smaller cores and wires, the memory density of core slowly increased. By the late 1960s, a density of about 32 kilobits per cubic foot (about 0.9 kilobits per litre)[citation needed] was typical. The cost declined over this period from about $1 per bit to about 1 cent per bit. Reaching this density requires extremely careful manufacturing, which was almost always carried out by hand in spite of repeated major efforts to automate the process. Core was almost universal until the introduction of the first semiconductor memory chips in the late 1960s, and especially dynamic random-access memory (DRAM) in the early 1970s. Initially, around the same price as core, DRAM was smaller and simpler to use. Core was driven from the market gradually between 1973 and 1978.