With the advent of 64-bit architectures comes enhanced capabilities, such as 64-bit integer arithmetic, a larger virtual address space, and 64-bit file systems. UNIX vendors are now faced with the task of incorporating this new technology into their products. In this paper, the authors propose both a short and long term plan for the evolution of the UNIX operating system to 64-bit architectures. The short term plan is designed to quickly make available many of the features of these new architectures, while requiring little change to the existing UNIX code base. The long term plan involves changing the traditional UNIX process model to take better advantage of the large virtual address space. The authors will describe the Single Address Space Operating System (SASOS) model, under which all programs and data reside in a single global virtual address space. This simplifies data sharing, process migration, and distributed system design in general. They will also present a survey of current research in this area.
