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Real-time Technology
Real-time computing (RTC) is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines". Ben-Ari, Mordechai; "Principles of Concurrent and Distributed Programming", ch. 16, Prentice Hall, 1990, , p. 164 The term "real-time" is also used in simulation to mean that the simulation's clock runs at the same speed as a real clock. Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually ''guarantee'' a response within any timeframe, although ''typical'' or ''expected'' response times may be given. Real-time processing ''fails'' if not completed within a specified deadline relative to an event; deadlines must always be met, regardless of system load. A real-time system has been desc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Real-time Communication
Real-time communication (RTC) is a category of software protocols and communication hardware media that gives real-time guarantees, which is necessary to support real-time guarantees of real-time computing. Real-time communication Protocols (computing), protocols are dependent not only on the Data integrity, validity and integrity of data transferred but also the timeliness of the transfer. Real-time communication systems are generally understood as one of two types: ''Hard Real-Time (HRT)'' and ''Soft Real-Time (SRT)''. The difference between a hard and soft real-time communication system is the consequences of incorrect operation. Safety-critical systems capable of causing catastrophic consequences upon a fault, such as Fly-by-wire, aircraft fly-by-wire systems, are designated as hard real-time, whereas non-critical but ideally real-time systems, such as hotel reservation systems, are designated as soft real-time. The designation of a real-time communication system as hard or sof ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simulation
A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model. Sometimes a clear distinction between the two terms is made, in which simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the simulation represents the evolution of the model over time. Another way to distinguish between the terms is to define simulation as experimentation with the help of a model. This definition includes time-independent simulations. Often, computer simulation, computers are used to execute the simulation. Simulation is used in many contexts, such as simulation of technology for performance tuning or optimizing, safety engineering, testing, training, education, and video games. Simulation is also used with scientific modelling of natural systems or human systems to gain insight into their functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt Latency
In computing, interrupt latency refers to the delay between the start of an Interrupt Request (IRQ) and the start of the respective Interrupt Service Routine (ISR). For many operating systems, devices are serviced as soon as the device's interrupt handler is executed. Interrupt latency may be affected by microprocessor design, interrupt controllers, interrupt masking, and the operating system's (OS) interrupt handling methods. Background There is usually a trade-off between interrupt latency, throughput, and processor utilization. Many of the techniques of CPU and OS design that improve interrupt latency will decrease throughput and increase processor utilization. Techniques that increase throughput may increase interrupt latency and increase processor utilization. Lastly, trying to reduce processor utilization may increase interrupt latency and decrease throughput. Minimum interrupt latency is largely determined by the interrupt controller circuit and its configuration. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dumb Terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. Most early computers only had a front panel to input or display bits and had to be connected to a terminal to print or input text through a keyboard. Teleprinters were used as early-day hard-copy terminals and predated the use of a computer screen by decades. The computer would typically transmit a line of data which would be printed on paper, and accept a line of data from a keyboard over a serial or other interface. Starting in the mid-1970s with microcomputers such as the Sphere 1, Sol-20, and Apple I, display circuitry and keyboards began to be integrated into personal and workstation computer systems, with the computer handling character generation and outputting to a CRT display such as a computer monitor or, sometimes, a consumer TV, but most larger computers continued to require termin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data General Business Basic
Data General Business Basic was a BASIC interpreter (based on a version from MAI Basic Four) marketed by Data General for their Nova minicomputer in the 1970s, and later ported to the Data General Eclipse MV and AViiON computers. Most business applications for the Nova were developed in Business Basic. Description Business Basic was an integer-only language inspired by COBOL, and contained powerful string-handling functions and the ability to manipulate indexed files very quickly. It also provided full control over the display screen, with cursor positioning, attribute setting, and region-blanking commands. Business Basic could interface to Data General's INFOS II database, and make calls directly to the operating system. A lock server gave multiple concurrent users efficient access to database records. Small business programs could be developed and debugged rapidly with Business Basic because of the interactive nature of the interpreter, but the language did not pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-sharing
In computing, time-sharing is the Concurrency (computer science), concurrent sharing of a computing resource among many tasks or users by giving each Process (computing), task or User (computing), user a small slice of CPU time, processing time. This quick switch between tasks or users gives the illusion of Parallel computing, simultaneous execution. It enables computer multitasking, multi-tasking by a single user or enables multiple-user sessions. Developed during the 1960s, its emergence as the prominent model of computing in the 1970s represented a major technological shift in the history of computing. By allowing many users to interact concurrent computing, concurrently with a single computer, time-sharing dramatically lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one, and promoted the Interactive computing, interactive use of computers and the development of new interactive application ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RT-11
RT-11 (Real-time 11) is a discontinued small, low-end, single-user real-time operating system for the full line of Digital Equipment Corporation PDP-11 16-bit computers. RT-11 was first implemented in 1970. It was widely used for real-time computing systems, process control, and data acquisition across all PDP-11s. It was also used for low-cost general-use computing. Features Source code RT-11 was written in assembly language. Heavy use of the conditional assembly and macro programming features of the MACRO-11 assembler allowed a significant degree of configurability and allowed programmers to specify high-level instructions otherwise unprovided for in machine code. RT-11 distributions included the source code of the operating system and its device drivers with all the comments removed and a program named "SYSGEN" which would build the operating system and drivers according to a user-specified configuration. Developer's documentation included a kernel listing that included ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until he was forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the early 1960s. The company produced a series of machines known as the Programmed Data Processor, PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foreground-background
Foreground-background is a scheduling algorithm that is used to control an execution of multiple processes on a single processor. It is based on two waiting lists, the first one is called foreground because this is the one in which all processes initially enter, and the second one is called background because all processes, after using all of their execution time in foreground, are moved to background. When a process becomes ready it begins its execution in foreground immediately, forcing the processor to give up execution of the current process in the background and execute the newly created process for a predefined period. This period is usually 2 or more quanta. If the process is not finished after its execution in the foreground it is moved to background waiting list where it will be executed only when the foreground list is empty. After being moved to the background, the process is then run longer than before, usually 4 quanta. The time of execution is increased because the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data General RDOS
The Data General RDOS (''Real-time Disk Operating System'') is a real-time operating system released in 1970. The software was bundled with the company's popular Nova and Eclipse minicomputers. Overview RDOS is capable of multitasking, with the ability to run up to 32 tasks (similar to the current term threads) simultaneously on each of two grounds ( foreground and background) within a 64 KB memory space. Later versions of RDOS are compatible with Data General's 16-bit Eclipse minicomputer line. A cut-down version of RDOS, without real-time background and foreground capability but still capable of running multiple threads and multi-user Data General Business Basic, is called Data General Diskette Operating System (DG-DOS or now—somewhat confusingly—simply DOS); another related operating system is RTOS, a Real-Time Operating System for diskless environments. RDOS on microNOVA-based "Micro Products" micro-minicomputers is sometimes called DG/RDOS. RDOS was super ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data General
Data General Corporation was an early minicomputer firm formed in 1968. Three of the four founders were former employees of Digital Equipment Corporation (DEC). Their first product, 1969's Data General Nova, was a 16-bit minicomputer intended to both outperform and cost less than the equivalent from DEC, the 12-bit PDP-8. A basic Nova system cost two-thirds or less than a similar PDP-8 while running faster, offering easy expandability, being significantly smaller, and proving more reliable in the field. Combined with Data General RDOS (DG/RDOS) and programming languages like Data General Business Basic, Novas provided a multi-user platform far ahead of many contemporary systems. A series of updated Nova machines were released through the early 1970s that kept the Nova line at the front of the 16-bit mini world. The Nova was followed by the Data General Eclipse, Eclipse series which offered much larger memory capacity while still being able to run Nova code without modification. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital On-screen Graphic
A digital on-screen graphic, digitally originated graphic (DOG, bug, network bug, or screenbug) is a watermark-like station logo that most television broadcasters overlay over a portion of the screen area of their programs to identify the channel. They are thus a form of permanent visual station identification, increasing brand recognition and asserting ownership of the video signal. The graphic identifies the source of programming, even if it has been time shifting, time-shifted—that is, recorded to videotape, DVD, or a digital personal video recorder such as TiVo. Many of these technologies allow viewers to skip or omit traditional between-programming station identification; thus the use of a DOG enables the station or network to enforce brand identification even when standard commercials are skipped. DOG watermarking helps to reduce off-the-air copyright infringement—for example, the distribution of a current series' episodes on DVD: the watermarked content is easily diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
