For many years, the primary developer and project leader was Bill Joy, who was a graduate student at the time; funding for this project was provided by DARPA. DARPA was interested in obtaining a programming platform and programmer's interface which would provide a robust, general purpose, time-sharing computing platform which would not become obsolete every time computing hardware was or is replaced. Such an operating system would allow US Department of Defense software, especially for intricate, long-term finance and logistics operations, to be quickly ported to new hardware as it became available.