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62-595: As with RSX-11 and VMS , Dave Cutler was the principal force behind the development of this operating system. Cutler's team developed the product after moving to the Seattle , Washington area to form the DECwest Engineering Group; DEC's first engineering group outside New England . Initial target platforms for VAXELN were the backplane interconnect computers such as the V-11 family . When VAXELN

124-950: A data-driven approach. IPC is used across a wide range of industries where precise control is important. The applications can range from controlling the temperature and level of a single process vessel, to a complete chemical processing plant with several thousand control loops. In automotive manufacturing, IPC ensures consistent quality by meticulously controlling processes like welding and painting. Mining operations are optimized with IPC monitoring ore crushing and adjusting conveyor belt speeds for maximum output. Dredging benefits from precise control of suction pressure, dredging depth and sediment discharge rate by IPC, ensuring efficient and sustainable practices. Pulp and paper production leverages IPC to regulate chemical processes (e.g., pH and bleach concentration) and automate paper machine operations to control paper sheet moisture content and drying temperature for consistent quality. In chemical plants, it ensures

186-488: A distributed control system (DCS, for large-scale or geographically dispersed processes) analyzes this sensor data transmitted to it, compares it to predefined setpoints using a set of instructions or a mathematical model called the control algorithm and then, in case of any deviation from these setpoints (e.g., temperature exceeding setpoint), makes quick corrective adjustments through actuators such as valves (e.g. cooling valve for temperature control), motors or heaters to guide

248-415: A few moments came up with better than a dozen candidate acronyms and names.  My purpose was to come up with a good acronym and then find some appropriate words to justify it.  For example, X always appealed to me as part of an acronym because it is pronounced so forcefully, inferring (at least to me) some power and drama.  I used a lot of X's.  These potential acronyms were submitted back to

310-659: A free license granted in May 1998 by Mentec Inc. Legal ownership of RSX-11A, RSX-11B, RSX-11C, RSX-11D, and IAS never changed hands; therefore it passed to Compaq when it acquired Digital in 1998 and then to Hewlett-Packard in 2002. In late 2015 Hewlett-Packard split into two separate companies ( HP Inc. and Hewlett Packard Enterprise ), so the current owner cannot be firmly established. No new commercial licenses have been issued since at least October 1979 (RSX-11A, RSX-11B, RSX-11C) or 1990 (IAS), and none of these operating systems have ever been licensed for hobbyist use. In 1968,

372-476: A lower priority. In order to support large programs within the PDP-11's relatively small virtual address space of 64 KB, a sophisticated semi-automatic overlay system was used; for any given program, this overlay scheme was produced by RSX's taskbuilder program (called TKB ). If the overlay scheme was especially complex, taskbuilding could take a rather long time (hours to days). The standard RSX prompt

434-477: A minimum and maximum for a property of the material or product, or a range within which the property must be. All loops are susceptible to disturbances and therefore a buffer must be used on process set points to ensure disturbances do not cause the material or product to go out of specifications. This buffer comes at an economic cost (i.e. additional processing, maintaining elevated or depressed process conditions, etc.). Process efficiency can be enhanced by reducing

496-419: A non-logged in user to execute a " HELP " command. When run on certain PDP-11 processors, each DEC operating system displays a characteristic light pattern on the processor console panel when the system is idle. These patterns are created by an idle task running at the lowest level. The RSX-11M light pattern is two sets of lights that sweep outwards to the left and right from the center of the console (inwards if

558-504: A permanently-staffed central control room. Effectively this was the centralization of all the localized panels, with the advantages of lower manning levels and easier overview of the process. Often the controllers were behind the control room panels, and all automatic and manual control outputs were transmitted back to plant. However, whilst providing a central control focus, this arrangement was inflexible as each control loop had its own controller hardware, and continual operator movement within

620-407: Is ">" or "MCR>", (for the "Monitor Console Routine". All commands can be shortened to their first three characters when entered and correspondingly all commands are unique in their first three characters. Only the login command of "HELLO" can be executed by a user not yet logged in. "HELLO" was chosen as the login command because only the first three characters, "HEL", are relevant and this allows

682-399: Is a Piping and instrumentation diagram . Commonly used control systems include programmable logic controller (PLC), Distributed Control System (DCS) or SCADA . A further example is shown. If a control valve were used to hold level in a tank, the level controller would compare the equivalent reading of a level sensor to the level setpoint and determine whether more or less valve opening

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744-453: Is a general model which shows functional manufacturing levels in a large process using processor and computer-based control. Referring to the diagram: Level 0 contains the field devices such as flow and temperature sensors (process value readings - PV), and final control elements (FCE), such as control valves ; Level 1 contains the industrialized Input/Output (I/O) modules, and their associated distributed electronic processors; Level 2 contains

806-416: Is asserted in binary files, source code and documentation alike. It was entirely developed internally by Digital. Therefore, no part of it is open source . However a copy of the kernel source is present in every RSX distribution, because it was used during the system generation process. The notable exception to this rule is Micro-RSX, which came with a pre-generated autoconfiguring binary kernel. Full sources

868-435: Is expected to come closely after. When manuals have different printing dates, the latest date is used. RSX-11S is a proper subset of RSX-11M, so release dates are always assumed to be the same as the corresponding version of RSX-11M. On the other side, RSX-11M Plus is an enhanced version of RSX-11M, so it is expected to be later than the corresponding version of RSX-11M. RSX-11S 4.0 RSX-11 is proprietary software . Copyright

930-477: Is fixed for the system, such as the vessel volume or the viscosity of the material. Output (y) is the metric used to determine the behavior of the system. The control output can be classified as measured, unmeasured, or unmonitored. Processes can be characterized as batch, continuous, or hybrid. Batch applications require that specific quantities of raw materials be combined in specific ways for particular duration to produce an intermediate or end result. One example

992-457: Is represented through variables that are smooth and uninterrupted in time. The control of the water temperature in a heating jacket , for example, is an example of continuous process control. Some important continuous processes are the production of fuels, chemicals and plastics. Continuous processes in manufacturing are used to produce very large quantities of product per year (millions to billions of pounds). Such controls use feedback such as in

1054-421: Is the production of adhesives and glues, which normally require the mixing of raw materials in a heated vessel for a period of time to form a quantity of end product. Other important examples are the production of food, beverages and medicine. Batch processes are generally used to produce a relatively low to intermediate quantity of product per year (a few pounds to millions of pounds). A continuous physical system

1116-619: The PDP-15 minicomputer, first released in 1971. The main architect for RSX-15 (later renamed XVM/RSX) was Dennis “Dan” Brevik. Commenting on the RSX acronym, Brevik says: "At first I called the new system DEX-15.  It was an acronym for 'Digital's Executive - for the PDP-15.'  The homonymic relation between DEC, DEX and deques (used as the primary linkage mechanism in the kernel) appealed to my sense of whimsy.  People readily adopted

1178-453: The PID controller A PID Controller includes proportional, integrating, and derivative controller functions. Applications having elements of batch and continuous process control are often called hybrid applications. The fundamental building block of any industrial control system is the control loop , which controls just one process variable. An example is shown in the accompanying diagram, where

1240-655: The System/360 architecture, the Russians and their allies sometimes significantly modified Western designs, and therefore many SM EVM machines were binary-incompatible with DEC offerings at the time. A clone of the RSX-11M operating system ran on the Romanian -made CORAL series family of computers (such as CORAL 2030, a clone of PDP-11). RSX-11 was often used for general-purpose timeshare computing, even though this

1302-409: The 1760s, process controls inventions were aimed to replace human operators with mechanized processes. In 1784, Oliver Evans created a water-powered flourmill which operated using buckets and screw conveyors. Henry Ford applied the same theory in 1910 when the assembly line was created to decrease human intervention in the automobile production process. For continuously variable process control it

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1364-475: The 1930s, pneumatic and electronic controllers, such as PID (Proportional-Integral-Derivative) controllers, were breakthrough innovations that laid the groundwork for modern control theory. The late 20th century saw the rise of programmable logic controllers (PLCs) and distributed control systems (DCS), while the advent of microprocessors further revolutionized IPC by enabling more complex control algorithms. Early process control breakthroughs came most frequently in

1426-532: The IND indirect command file processor program was currently running on older versions of RSX). By contrast, the IAS light pattern was a single bar of lights that swept leftwards. Correspondingly, a jumbled light pattern (reflecting memory fetches) is a visible indication that the computer is under load (and the idle task is not being executed). Other PDP-11 operating systems such as RSTS/E have their own distinctive patterns in

1488-540: The Soviet Government decided that manufacturing copies of IBM mainframes and DEC minicomputers, in cooperation with other COMECON countries, was more practical than pursuing original designs. Cloning of DEC designs began in 1974, under the name of SM EVM ( Russian : СМ ЭВМ or Russian : Система Малых Электронно-Вычислительных Машин , lit.   'System of Small electronic computing machines'). As happened with ES EVM mainframes based on

1550-624: The UK, also set up the team that designed and prototyped the Interactive Application System (IAS) operating system in the UK; IAS was a variant of RSX-11D more suitable for time sharing . Later development and release of IAS was led by Andy Wilson , in Digital's UK facilities. Below are estimated release dates for RSX-11 and IAS. Data is taken from the printing date of the associated documentation. General availability date

1612-462: The acronym without question. But in a short time I was asked to submit the choice to the corporate legal department for a trademark search and registration.  They sent me a memo that DEX was already trademarked by some paper company and I would have to rename the product.  I pointed out to them that software and paper mills didn't seem to have a hell of a lot of connection, but they wouldn't budge. So I sat down with pencil and paper, and in

1674-404: The board and erased all the rest until the only writing left was RSX.  It even looked right. I have absolutely no memory about the other candidate acronyms.  They are lost forever, I suppose.  Well, maybe there's just a chance that the legal department kept copies of the correspondence - after all they are lawyers and they seem to hold on to everything (especially my money). Oh, by

1736-709: The console lights. Process control Industrial process control (IPC) or simply process control is a system used in modern manufacturing which uses the principles of control theory and physical industrial control systems to monitor, control and optimize continuous industrial production processes using control algorithms. This ensures that the industrial machines run smoothly and safely in factories and efficiently use energy to transform raw materials into high-quality finished products with reliable consistency while reducing energy waste and economic costs , something which could not be achieved purely by human manual control. In IPC, control theory provides

1798-453: The control room was required to view different parts of the process. With the coming of electronic processors and graphic displays it became possible to replace these discrete controllers with computer-based algorithms, hosted on a network of input/output racks with their own control processors. These could be distributed around the plant, and communicate with the graphic display in the control room or rooms. The distributed control system (DCS)

1860-413: The current rate of change; this was then given a mathematical treatment by Minorsky. His goal was stability, not general control, which simplified the problem significantly. While proportional control provided stability against small disturbances, it was insufficient for dealing with a steady disturbance, notably a stiff gale (due to steady-state error ), which required adding the integral term. Finally,

1922-439: The customers and strengthens the company's reputation. It improves safety by detecting and alerting human operators about potential issues early, thus preventing accidents, equipment failures, process disruptions and costly downtime. Analyzing trends and behaviors in the vast amounts of data collected real-time helps engineers identify areas of improvement, refine control strategies and continuously enhance production efficiency using

VAXELN - Misplaced Pages Continue

1984-504: The decision, for the first release, to use the programming language Pascal as its system programming language . The development team built the first product in approximately 18 months. Other languages, including C , Ada , and Fortran were supported in later releases of the system as optional extras. A relational database , named VAX Rdb/ELN was another optional component of the system. Later versions of VAXELN supported an X11 server named EWS (VAXELN Window Server). VAXELN with EWS

2046-419: The derivative term was added to improve stability and control. Process control of large industrial plants has evolved through many stages. Initially, control would be from panels local to the process plant. However this required a large manpower resource to attend to these dispersed panels, and there was no overall view of the process. The next logical development was the transmission of all plant measurements to

2108-536: The design of large high volume and complex processes, which could not be otherwise economically or safely operated. Historical milestones in the development of industrial process control began in ancient civilizations, where water level control devices were used to regulate water flow for irrigation and water clocks. During the Industrial Revolution in the 18th century, there was a growing need for precise control over boiler pressure in steam engines. In

2170-436: The developers. Some documentation and marketing material had already been printed referring to the product as ELAN, and samples of these posters were prized for many years by members of the original team. RSX-11 RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation . In widespread use through the late 1970s and early 1980s, RSX-11

2232-537: The direction of Ron McLean a derivative of RSX-11M, called RSX-20F, was developed to run on the PDP-11/40 front-end processor for the KL10 PDP-10 CPU. Meanwhile, RSX-11D saw further developments: under the direction of Garth Wolfendale (project leader 1972–1976) the system was redesigned and saw its first commercial release. Support for the 22-bit PDP-11/70 system was added. Wolfendale, originally from

2294-432: The flow rate in a pipe is controlled by a PID controller , assisted by what is effectively a cascaded loop in the form of a valve servo-controller to ensure correct valve positioning. Some large systems may have several hundreds or thousands of control loops. In complex processes the loops are interactive, so that the operation of one loop may affect the operation of another. The system diagram for representing control loops

2356-431: The form of water control devices. Ktesibios of Alexandria is credited for inventing float valves to regulate water level of water clocks in the 3rd century BC. In the 1st century AD, Heron of Alexandria invented a water valve similar to the fill valve used in modern toilets. Later process controls inventions involved basic physics principles. In 1620, Cornelis Drebbel invented a bimetallic thermostat for controlling

2418-671: The fully fledged RSX-11D disk-based operating system, which first appeared on the PDP-11/40 and PDP-11/45 in early 1973. The project leader for RSX-11D up to version 4 was Henry Krejci . While RSX-11D was being completed, Digital set out to adapt it for a small memory footprint , giving birth to RSX-11M, first released in 1973. From 1971 to 1976, the RSX-11M project was spearheaded by noted operating system designer Dave Cutler , then at his first project. Principles first tried in RSX-11M appear also in later designs led by Cutler, DEC's VMS and MICA and Microsoft's Windows NT . Under

2480-457: The legal department.  At the time I had no favorite. In a week or so they came back with a subset of my list that they could accept as trademarks.  It was left to me to make the final choice. Bob Decker and I met in my office one afternoon to discuss the choice.  Bob was a marketeer who worked for me.  I chalked all the candidates on the blackboard and we started going through them one by one, pronouncing each out loud, savoring

2542-455: The margins necessary to ensure product specifications are met. This can be done by improving the control of the process to minimize the effect of disturbances on the process. The efficiency is improved in a two step method of narrowing the variance and shifting the target. Margins can be narrowed through various process upgrades (i.e. equipment upgrades, enhanced control methods, etc.). Once margins are narrowed, an economic analysis can be done on

VAXELN - Misplaced Pages Continue

2604-505: The process back to the desired operational range. This creates a continuous closed-loop cycle of measurement, comparison, control action, and re-evaluation which guarantees that the process remains within established parameters. The HMI (Human-Machine Interface) acts as the "control panel" for the IPC system where small number of human operators can monitor the process and make informed decisions regarding adjustments. IPCs can range from controlling

2666-583: The safe and efficient production of chemicals by controlling temperature, pressure and reaction rates. Oil refineries use it to smoothly convert crude oil into gasoline and other petroleum products. In power plants, it helps maintain stable operating conditions necessary for a continuous electricity supply. In food and beverage production, it helps ensure consistent texture, safety and quality. Pharmaceutical companies relies on it to produce life-saving drugs safely and effectively. The development of large industrial process control systems has been instrumental in enabling

2728-474: The sound, trying to get the feel of each one.  After ten minutes or so we had narrowed down the selection to three. Bob sat back in silence as I kept looking at each acronym, seeing how it flowed off my tongue, what impression it gave me, and most importantly, the overall feeling about it.  After three or four minutes a strong feeling came over me about one of them.  It really felt right.  I looked at Bob and announced, "It's RSX".  I went to

2790-409: The supervisory computers, which collate information from processor nodes on the system, and provide the operator control screens; Level 3 is the production control level, which does not directly control the process, but is concerned with monitoring production and monitoring targets; Level 4 is the production scheduling level. To determine the fundamental model for any process, the inputs and outputs of

2852-401: The system are defined differently than for other chemical processes. The balance equations are defined by the control inputs and outputs rather than the material inputs. The control model is a set of equations used to predict the behavior of a system and can help determine what the response to change will be. The state variable (x) is a measurable variable that is a good indicator of the state of

2914-415: The system, such as temperature (energy balance), volume (mass balance) or concentration (component balance). Input variable (u) is a specified variable that commonly include flow rates. The entering and exiting flows are both considered control inputs. The control input can be classified as a manipulated, disturbance, or unmonitored variable. Parameters (p) are usually a physical limitation and something that

2976-572: The temperature and level of a single process vessel (controlled environment tank for mixing, separating, reacting, or storing materials in industrial processes.) to a complete chemical processing plant with several thousand control feedback loops. IPC provides several critical benefits to manufacturing companies. By maintaining a tight control over key process variables, it helps reduce energy use, minimize waste and shorten downtime for peak efficiency and reduced costs. It ensures consistent and improved product quality with little variability, which satisfies

3038-416: The temperature in a furnace. In 1681, Denis Papin discovered the pressure inside a vessel could be regulated by placing weights on top of the vessel lid. In 1745, Edmund Lee created the fantail to improve windmill efficiency; a fantail was a smaller windmill placed 90° of the larger fans to keep the face of the windmill pointed directly into the oncoming wind. With the dawn of the Industrial Revolution in

3100-561: The theoretical framework to understand system dynamics, predict outcomes and design control strategies to ensure predetermined objectives, utilizing concepts like feedback loops, stability analysis and controller design. On the other hand, the physical apparatus of IPC, based on automation technologies, consists of several components. Firstly, a network of sensors continuously measure various process variables (such as temperature, pressure, etc.) and product quality variables. A programmable logic controller (PLC, for smaller, less complex processes) or

3162-428: The way, the acronym stood for 'Real-Time System Executive.'  Years later that was changed to 'Resource Sharing Executive,' which I think is even better. ...And that is how RSX got its name, on the 3rd floor of building 5 in the old mill." The porting effort first produced small paper tape based real-time executives (RSX-11A, RSX-11C) which later gained limited support for disks (RSX-11B). RSX-11B then evolved into

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3224-499: Was available as a separate product to those who already had a binary license, for reference purposes. Ownership of RSX-11S, RSX-11M, RSX-11M Plus and Micro/RSX was transferred from Digital to Mentec Inc. in March 1994 as part of a broader agreement. Mentec Inc. was the US subsidiary of Mentec Limited , an Irish firm specializing in PDP-11 hardware and software support. In 2006 Mentec Inc.

3286-547: Was born. The introduction of DCSs allowed easy interconnection and re-configuration of plant controls such as cascaded loops and interlocks, and easy interfacing with other production computer systems. It enabled sophisticated alarm handling, introduced automatic event logging, removed the need for physical records such as chart recorders, allowed the control racks to be networked and thereby located locally to plant to reduce cabling runs, and provided high level overviews of plant status and production levels. The accompanying diagram

3348-786: Was debuted in Las Vegas in the early 1980s, with a variety of amusing application software written by the development team, ranging from a system that composed and played minuets to a robotic system that played and solved the Tower of Hanoi puzzle. VAXELN was not ported to the DEC Alpha architecture, and instead was replaced with a Digital-supported port of VxWorks to Alpha, and a VAXELN application programming interface ( API ) compatibility layer for that platform. In 1999, SMART Modular Technologies acquired Compaq 's (formerly Digital's) embedded systems division, which included VAXELN. The system

3410-524: Was declared bankrupt while Mentec Ltd. was acquired by Irish firm Calyx in December 2006. The PDP-11 software, which was owned by Mentec Inc. was then bought by XX2247 LLC, which is the owner of the software today. It is unclear if new commercial licenses are possible to buy at this time. Hobbyists can run RSX-11M (version 4.3 or earlier) and RSX-11M Plus (version 3.0 or earlier) on the SIMH emulator thanks to

3472-416: Was influential in the development of later operating systems such as VMS and Windows NT . As the original Real-Time System Executive name suggests, RSX was designed (and commonly used) for real time use, with process control a major use. It was also popular for program development and general computing. RSX-11 began as a port to the PDP-11 architecture of the earlier RSX-15 operating system for

3534-428: Was necessary to keep the level constant. A cascaded flow controller could then calculate the change in the valve position. The economic nature of many products manufactured in batch and continuous processes require highly efficient operation due to thin margins. The competing factor in process control is that products must meet certain specifications in order to be satisfactory. These specifications can come in two forms:

3596-509: Was not until 1922 that a formal control law for what we now call PID control or three-term control was first developed using theoretical analysis, by Russian American engineer Nicolas Minorsky . Minorsky was researching and designing automatic ship steering for the US Navy and based his analysis on observations of a helmsman . He noted the helmsman steered the ship based not only on the current course error, but also on past error, as well as

3658-466: Was originally supposed to be named Executive for Local Area Network (ELAN), but DEC discovered at the last minute that the word Elan was trademarked in a European country where DEC wished to conduct business. The company holding the trademark was the Slovenian sports equipment manufacturer Elan . To avoid litigation, DEC quickly renamed it to VAXELN by dropping the A, much to the disgruntlement of

3720-443: Was the target market for the competing RSTS/E operating system. RSX-11 provided features to ensure better than a maximum necessary response time to peripheral device input (i.e. real-time processing), its original intended use. These features included the ability to lock a process (called a task under RSX) into memory as part of system boot up and to assign a process a higher priority so that it would execute before any processes with

3782-478: Was used as the operating system for the VT1300 X terminal , and was sometimes used to convert old VAXstation hardware into X terminals. Beginning with version 4.3, VAXELN gained support for TCP/IP networking and a subset of POSIX APIs. VAXELN allowed the creation of a self-contained embedded system application that would run on VAX (and later MicroVAX) hardware with no other operating system present. The system

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3844-695: Was well under way, Cutler spearheaded the next project, the MicroVAX I , the first VAX microcomputer . Although it was a low-volume product compared with the New England-developed MicroVAX II , the MicroVAX I demonstrated the set of architectural decisions needed to support a single-board implementation of the VAX computer family, and it also provided a platform for embedded system applications written for VAXELN. The VAXELN team made

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