The design described in this paper covers a non-traditional, rotary positioner for a 14 inch, mid-range magnetic disk memory. It was intended to provide high performance and track density while retaining traditional advantages found in rotary positioners such as high reliability, and low cost, power, weight, and size. The paper describes positioner motor architecture and design, head support arm architecture and design, performance achieved by the total servo system including positioner, and finally, conclusions reached as a result of this design approach. Extensive use of computer modelling and computer assisted testing and analysis is highlighted. In particular, modal analysis results obtained from theoretical studies are described and compared with positioner performance measurements.