This drum iwas intended to replace the original drum operational with CSIR Mk 1 in Sydney. The drum has 30 heads, but was most likely of the same memory capacity as the operational drum ie. 1024, 20 bit words. It was never finished and never actually used with CSIRAC.

When CSIR Mk1 (later CSIRAC) began operating, it only had a mercury delay line storage system. In 1950, work began on the development of an auxiliary store in the form of a magnetic drum to provide additional data storage capacity. It was completed and trialled by 1952. The development of the drum was the responsibily of Brian Cooper. Once the drum storage was running, Trevor Pearcey, one of CSIRAC's two designers, requested that another drum be constructed with quadruple the storage capacity.This project reached an advanced stage but was not completed. Instead, a disk storage was developed in Sydney and fitted to the computer after it was transferred from Sydney to Melbourne

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