Optimal number of disc clock tracks for block-oriented rotating associative processors

Block-oriented rotating associative processors provide a highly cost-effective solution to the need for parallel processing of large volumes of data in information storage and retrieval applications. Such processors are implemented by incorporating some processing logic into each read/write head of a fixed-head (head-per-track) disc memory. With non-self-clocked data recording, which offers higher storage densities, the usual data storage format is to assign the fixed capacity dictated by the maximum bit density and the length of the innermost (shortest) track to all tracks, thus making it possible to use a single clock track for the synchronisation of read and write operations. The author notes that with a single clock track about half of the total recording capacity of the disk surface is wasted. This leads to the proposal for dividing the tracks into groups, with one clock track for each group. It is shown that with optimal design, 90-95% of the useful disk capacity can be utilised. This represents a 70-90% improvement over the case of a single clock track and is achieved at virtually no extra cost.