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Pilot (operating System)
Pilot is 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. Overview 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 (run until blocked) system based on monitors. Pilot included a debugger, Co-Pilot, that could debug a frozen snapshot of the operating system, written to disk. A typical Pilot workstation ran 3 operating systems at once on 3 different disk volumes : Co-Co-Pilot (a backup debugger in case the main operating system crashed), Co-Pilot (th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PARC (company)
Future Concepts division (formerly Palo Alto Research Center, PARC and Xerox PARC) is a research and development company in Palo Alto, California. It was founded in 1969 by Jack Goldman, Jacob E. "Jack" Goldman, chief scientist of Xerox Corporation, as a division of Xerox, tasked with creating computer technology-related products and hardware systems. Xerox PARC has been foundational to numerous revolutionary computer developments, including laser printing, Ethernet, the modern personal computer, graphical user interface (GUI) and desktop metaphor–paradigm, object-oriented programming, ubiquitous computing, electronic paper, amorphous silicon (a-Si) applications, the computer mouse, and very-large-scale integration (VLSI) for semiconductors. Unlike Xerox's existing research laboratory in Rochester, New York, which focused on refining and expanding the company's copier business, Goldman's "Advanced Scientific & Systems Laboratory" aimed to pioneer new technologies in advanced ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Memory
In computing, virtual memory, or virtual storage, is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very large (main) memory". The computer's operating system, using a combination of hardware and software, maps memory addresses used by a program, called '' virtual addresses'', into ''physical addresses'' in computer memory. Main storage, as seen by a process or task, appears as a contiguous address space or collection of contiguous segments. The operating system manages virtual address spaces and the assignment of real memory to virtual memory. Address translation hardware in the CPU, often referred to as a memory management unit (MMU), automatically translates virtual addresses to physical addresses. Software within the operating system may extend these capabilities, utilizing, e.g., disk storage, to provide a virtual address space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proprietary Operating Systems
{{Short pages monitor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Human–computer Interaction
History is the systematic study of the past, focusing primarily on the human past. As an academic discipline, it analyses and interprets evidence to construct narratives about what happened and explain why it happened. Some theorists categorize history as a social science, while others see it as part of the humanities or consider it a hybrid discipline. Similar debates surround the purpose of history—for example, whether its main aim is theoretical, to uncover the truth, or practical, to learn lessons from the past. In a more general sense, the term ''history'' refers not to an academic field but to the past itself, times in the past, or to individual texts about the past. Historical research relies on primary and secondary sources to reconstruct past events and validate interpretations. Source criticism is used to evaluate these sources, assessing their authenticity, content, and reliability. Historians strive to integrate the perspectives of several sources to develop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeline Of Operating Systems
This article presents a timeline of events in the history of computer operating systems from 1951 to the current day. For a narrative explaining the overall developments, see the History of operating systems. 1950s * 1951 ** LEO I 'Lyons Electronic Office' was the commercial development of EDSAC computing platform, supported by British firm J. Lyons and Co. * 1953 ** DYSEAC - an early machine capable of distributing computing * 1955 ** General Motors Operating System made for IBM 701 ** MIT's Tape Director operating system made for UNIVAC 1103 * 1956 ** GM-NAA I/O for IBM 704, based on General Motors Operating System * 1957 ** Atlas Supervisor (Manchester University) (''Atlas computer project start'') ** BESYS (Bell Labs), for IBM 704, later IBM 7090 and IBM 7094 * 1958 ** University of Michigan Executive System (UMES), for IBM 704, 709, and 7090 * 1959 ** SHARE Operating System (SOS), based on GM-NAA I/O 1960s * 1960 ** IBSYS (IBM for its 7090 and 7094) * 1961 ** ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monitor (synchronization)
In concurrent programming, a monitor is a synchronization construct that prevents threads from concurrently accessing a shared object's state and allows them to wait for the state to change. They provide a mechanism for threads to temporarily give up exclusive access in order to wait for some condition to be met, before regaining exclusive access and resuming their task. A monitor consists of a mutex (lock) and at least one condition variable. A condition variable is explicitly 'signalled' when the object's state is modified, temporarily passing the mutex to another thread 'waiting' on the condition variable. Another definition of monitor is a thread-safe class, object, or module that wraps around a mutex in order to safely allow access to a method or variable by more than one thread. The defining characteristic of a monitor is that its methods are executed with mutual exclusion: At each point in time, at most one thread may be executing any of its methods. By using one or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
A kernel is a computer program at the core of a computer's operating system that always has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the use of common resources, such as CPU, cache, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inter-process Communication
In computer science, interprocess communication (IPC) is the sharing of data between running Process (computing), processes in a computer system. Mechanisms for IPC may be provided by an operating system. Applications which use IPC are often categorized as client–server model, clients and servers, where the client requests data and the server responds to client requests. Many applications are both clients and servers, as commonly seen in distributed computing. IPC is very important to the design process for microkernels and nanokernels, which reduce the number of functionalities provided by the kernel. Those functionalities are then obtained by communicating with servers via IPC, leading to a large increase in communication when compared to a regular monolithic kernel. IPC interfaces generally encompass variable analytic framework structures. These processes ensure compatibility between the multi-vector protocols upon which IPC models rely. An IPC mechanism is either Synchroni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xerox Star
The Xerox Star workstation, officially named Xerox Star 8010 Information System, is the first commercial personal computer to incorporate technologies that have since become standard in personal computers, including a bitmapped display, a window-based graphical user interface, icons, folders, mouse (two-button), Ethernet networking, file servers, print servers, and email. Introduced by Xerox Corporation on April 27, 1981, the name ''Star'' technically refers only to the software sold with the system for the office automation market. The 8010 workstations were also sold with software based on the programming languages Lisp and Smalltalk for the smaller research and software development market. History The Xerox Alto The Xerox Star system's concept owes much to the Xerox Alto, an experimental workstation designed by the Xerox Palo Alto Research Center (PARC). The first Alto became operational in 1972. The Alto had been strongly influenced by what its designers had seen previ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Source Lines Of Code
Source lines of code (SLOC), also known as lines of code (LOC), is a software metric used to measure the size of a computer program by counting the number of lines in the text of the program's source code. SLOC is typically used to predict the amount of effort that will be required to develop a program, as well as to estimate programming productivity or maintainability once the software is produced. Measurement methods Multiple useful comparisons involve only the order of magnitude of lines of code in a project. Using lines of code to compare a 10,000-line project to a 100,000-line project is far more useful than when comparing a 20,000-line project with a 21,000-line project. While it is debatable exactly how to measure lines of code, discrepancies of an order of magnitude can be clear indicators of software complexity or man-hours. There are two major types of SLOC measures: physical SLOC (LOC) and logical SLOC (LLOC). Specific definitions of these two measures vary, but the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Programming Language
A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually defined by a formal language. Languages usually provide features such as a type system, Variable (computer science), variables, and mechanisms for Exception handling (programming), error handling. An Programming language implementation, implementation of a programming language is required in order to Execution (computing), execute programs, namely an Interpreter (computing), interpreter or a compiler. An interpreter directly executes the source code, while a compiler produces an executable program. Computer architecture has strongly influenced the design of programming languages, with the most common type (imperative languages—which implement operations in a specified order) developed to perform well on the popular von Neumann architecture. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
