IBM 2361 Large Capacity Storage

The IBM 2361 Large Capacity Storage was a component of the IBM System/360 models 50, 65 (when not being used as a multiprocessor), and 75 computers. Storage was implemented using magnetic cores, the cycle time was 8 microseconds and the access time was 3.6 microseconds. This component was also called IBM 2361 Core Storage, IBM 2361 Large Core Storage, and LCS.

In addition to its use on System/360, the IBM 2361 was also provided to NASA for use on their IBM 7094 real-time system.

There were two models of the IBM 2361: model 1 had 1,048,576 bytes and model 2 had 2,097,152 bytes.

The IBM 2361 could be shared between two System/360 computers. When sharing is between two model 50s, two model 65s, two model 75s, or a model 65 and a model 75, the two systems must have the same amount of main storage. When one of the sharing systems is a model 50 and the other a model 65 or model 75, the model 50 may have less main storage than the model 65 or model 75.

If a system contained an even number of IBM 2361 components and at least one model 65 or model 75 processor, the IBM 2361s could be interleaved to improve sequential access time. With interleaving, the first 64-bit word was contained in the first IBM 2361, the second in the second, the third in the first, and so forth. When doing sequential access, one IBM 2361 could complete its cycle while the other IBM 2361 was starting the next cycle.

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