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Phantom OS
Phantom OS is an Persistence_(computer_science)#Orthogonal_or_transparent_persistence, orthogonally persistent managed code general-purpose operating system. It is based on a concept of persistent virtual memory, and executes bytecode in a virtual machine. It is one of a few OSes not based on the classic concepts of Unix-like systems. Phantom is based on the principle that "Everything is an Object (computer science), object", in contrast to the Unix-like approach of "Everything is a file". Overview Phantom was founded by and is being developed mostly by Russian programmers. It is free and open-source software (FOSS) released under a GNU Lesser General Public License (LGPL). Basics Managed code – Memory protection on object level, rather than Process (computing), process level; absence of pointer arithmetic in managed code avoids many problems that exist and occur in unmanaged code. Global address space – Inexpensive inter-process communication (IPC). Single address space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Real-time Operating System
A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. A RTOS is distinct from a time-sharing operating system, such as Unix, which manages the sharing of system resources with a scheduler, data buffers, or fixed task prioritization in multitasking or multiprogramming environments. All operations must verifiably complete within given time and resource constraints or else fail safe. Real-time operating systems are event-driven and preemptive, meaning the OS can monitor the relevant priority of competing tasks, and make changes to the task priority. Characteristics A key characteristic of an RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is "jitter". A "hard" real-time operating system (hard RTOS) has less jitter than a "soft" real-time operating system (soft RTOS); a l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object (computer Science)
In software development, an object is an entity that has state, behavior, and identity. An object can model some part of reality or can be an invention of the design process whose collaborations with other such objects serve as the mechanisms that provide some higher-level behavior. Put another way, an object represents an individual, identifiable item, unit, or entity, either real or abstract, with a well-defined role in the problem domain. A programming language can be classified based on its support for objects. A language that provides an encapsulation construct for state, behavior, and identity is classified as object-based. If the language also provides polymorphism and inheritance it is classified as object-oriented. A language that supports creating an object from a class is classified as class-based. A language that supports object creation via a template object is classified as prototype-based. The concept of object is used in many different software contexts, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( ) is a family of open source Unix-like operating systems based on the Linux kernel, an kernel (operating system), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically package manager, packaged as a Linux distribution (distro), which includes the kernel and supporting system software and library (computing), libraries—most of which are provided by third parties—to create a complete operating system, designed as a clone of Unix and released under the copyleft GPL license. List of Linux distributions, Thousands of Linux distributions exist, many based directly or indirectly on other distributions; popular Linux distributions include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while commercial distributions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are frequently used in server platforms. Many Linux distributions use the word "Linux" in their name, but the Free ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porting
In software engineering, porting is the process of adapting software for the purpose of achieving some form of execution in a computing environment that is different from the one that a given program (meant for such execution) was originally designed for (e.g., different CPU, operating system, or third party library). The term is also used when software/hardware is changed to make them usable in different environments. Software is ''portable'' when the cost of porting it to a new platform is significantly less than the cost of writing it from scratch. The lower the cost of porting software relative to its implementation cost, the more portable it is said to be. This is distinct from cross-platform software, which is designed from the ground up without any single " native" platform. Etymology The term "port" is derived from the Latin '' portāre'', meaning "to carry". When code is not compatible with a particular operating system or architecture, the code must be "carried" to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
POSIX
The Portable Operating System Interface (POSIX; ) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines application programming interfaces (APIs), along with command line shells and utility interfaces, for software compatibility (portability) with variants of Unix and other operating systems. POSIX is also a trademark of the IEEE. POSIX is intended to be used by both application and system developers. As of POSIX 2024, the standard is aligned with the C17 language standard. Name Originally, the name "POSIX" referred to IEEE Std 1003.1-1988, released in 1988. The family of POSIX standards is formally designated as IEEE 1003 and the ISO/IEC standard number is ISO/ IEC 9945. The standards emerged from a project that began in 1984 building on work from related activity in the ''/usr/group'' association. Richard Stallman suggested the name ''POSIX'' to the IEEE instead of the former ''IEEE-IX''. Th ... [...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] |
Java Virtual Machine
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform. The JVM reference implementation is developed by the OpenJDK project as open source code and includes a JIT compiler called HotSpot. The commercially supported Java releases available from Oracle are based on the OpenJDK runtime. Eclipse OpenJ9 is another open source JVM for OpenJDK. JVM specification The Java virtual machine is an abstract (virtual) computer defined by a specification. It is a part of the Java runtime environment. The garbage collection ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Single Address Space Operating System
In computer science, a single address space operating system (or SASOS) is an operating system that provides only one globally shared address space for all processes. In a single address space operating system, numerically identical (virtual memory) logical addresses in different processes all refer to exactly the same byte of data. In a traditional OS with private per-process address space, memory protection is based on address space boundaries ("address space isolation"). Single address-space operating systems make translation and protection orthogonal, which in no way weakens protection. The core advantage is that pointers (i.e. memory references) have global validity, meaning their meaning is independent of the process using it. This allows sharing pointer-connected data structures across processes, and making them persistent, i.e. storing them on backup store. Some processor architectures have direct support for protection independent of translation. On such architectures, ... [...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] |
Pointer Arithmetic
In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer ''references'' a location in memory, and obtaining the value stored at that location is known as ''dereferencing'' the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture. Using pointers significantly improves performance for repetitive operations, like traversing iterable data structures (e.g. strings, lookup tables, control tables, linked lists, and tree structures). In particular, it is often much cheaper in time and space to copy and derefere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process (computing)
In computing, a process is the Instance (computer science), instance of a computer program that is being executed by one or many thread (computing), threads. There are many different process models, some of which are light weight, but almost all processes (even entire virtual machines) are rooted in an operating system (OS) process which comprises the program code, assigned system resources, physical and logical access permissions, and data structures to initiate, control and coordinate execution activity. Depending on the OS, a process may be made up of multiple threads of execution that execute instructions Concurrency (computer science), concurrently. While a computer program is a passive collection of Instruction set, instructions typically stored in a file on disk, a process is the execution of those instructions after being loaded from the disk into memory. Several processes may be associated with the same program; for example, opening up several instances of the same progra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free And Open-source Software
Free and open-source software (FOSS) is software available under a license that grants users the right to use, modify, and distribute the software modified or not to everyone free of charge. FOSS is an inclusive umbrella term encompassing free software and open-source software. The rights guaranteed by FOSS originate from the "Four Essential Freedoms" of '' The Free Software Definition'' and the criteria of '' The Open Source Definition''. All FOSS can have publicly available source code, but not all source-available software is FOSS. FOSS is the opposite of proprietary software, which is licensed restrictively or has undisclosed source code. The historical precursor to FOSS was the hobbyist and academic public domain software ecosystem of the 1960s to 1980s. Free and open-source operating systems such as Linux distributions and descendants of BSD are widely used, powering millions of servers, desktops, smartphones, and other devices. Free-software licenses and open-so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
