Aside from its novel aspects, however, Pilot's real significance is its careful integration, in a single relatively compact system, of a number of good ideas which have previously tended to appear individually, often in systems which were demonstration vehicles not intended to support serious client programs. The combination of streams, packet communications, a hierarchical virtual memory mapped to a large file space, concurrent programming support, and a modular high-level language, provides an environment with relatively few artificial limitations on the size and complexity of the client programs which can be supported.
Acknowledgments. The primary design and implementation of Pilot were done by the authors. Some of the earliest ideas were contributed by D. Gifford, R. Metcalfe, W. Shultz, and D. Stottlemyre. More recent contributions have been made by C. Fay, R. Gobbel, F. Howard, C. Jose, and D. Knutsen. Since the inception of the project, we have had continuous fruitful interaction with all the members of the Mesa language group; in particular, R. Johnsson, J. Sandman, and J. Wick have provided much of the software that stands on the border between Pilot and Mesa. We are also indebted to P. Jarvis and V. Schwartz, who designed and implemented some of the low-level input/output drivers. The success of the close integration of Mesa and Pilot with the machine architecture is largely due to the talent and energy of the people who designed and built the hardware and microcode for our personal computer.
Received June 1979; accepted September 1979; revised November 1979