Pilot (operating system)
Encyclopedia
Pilot was a single-user, multitasking
operating system
designed by Xerox PARC in early 1977. Pilot was written in the Mesa programming language
, totalling about 24,000 lines of code
.
Pilot was designed as a single user system in a highly networked environment of other Pilot systems, with interfaces designed for inter-process communication
(IPC) across the network via the Pilot stream interface. Pilot combined virtual memory
and file storage into one subsystem, and used the manager/kernel architecture for managing the system and its resources. Its designers considered a non-preemptive multitasking model, but later chose a preemptive system based on monitors
.
Pilot was used as the operating system for the Xerox Star
workstation.
Computer multitasking
In computing, multitasking is a method where multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
designed by Xerox PARC in early 1977. Pilot was written in the Mesa programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
, totalling about 24,000 lines of code
Source lines of code
Source lines of code is a software metric used to measure the size of a software program by counting the number of lines in the text of the program's source code...
.
Pilot was designed as a single user system in a highly networked environment of other Pilot systems, with interfaces designed for inter-process communication
Inter-process communication
In computing, Inter-process communication is a set of methods for the exchange of data among multiple threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC methods are divided into methods for message passing, synchronization, shared...
(IPC) across the network via the Pilot stream interface. Pilot combined virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
and file storage into one subsystem, and used the manager/kernel architecture for managing the system and its resources. Its designers considered a non-preemptive multitasking model, but later chose a preemptive system based on monitors
Monitor (synchronization)
In concurrent programming, a monitor is an object or module intended to be used safely by more than one thread. The defining characteristic of a monitor is that its methods are executed with mutual exclusion. That is, at each point in time, at most one thread may be executing any of its methods...
.
Pilot was used as the operating system for the Xerox Star
Xerox Star
The Star workstation, officially known as the Xerox 8010 Information System, was introduced by Xerox Corporation in 1981. It was the first commercial system to incorporate various technologies that today have become commonplace in personal computers, including a bitmapped display, a window-based...
workstation.
Further reading
- Horsley, T.R., and Lynch, W.C. Pilot: A software engineering case history. In Proc. 4th Int. Conf. Software Engineering, Munich, Germany, Sept. 1979, pp. 94-99.