IBM 653 Auxiliary Unit

The IBM 653 was used for immediate access storage, indexing registers and automatic floating decimal arithmetic. It was an integral component of tape processing combinations, and was available separately as high-speed "working" storage to increase the 650's processing speeds. It received blocks of information -- data and instructions -- transferred from the drum in single operations. These blocks were then individually processed from core storage. As soon as one block had been processed, a new one was transferred in for processing, and so on. In this fashion, the problem was worked from core storage instead of the drum.