577:'s monitors and provide the opportunity for controlled mutual exclusion and synchronization between client processes, using MCP EVENTs and the Dahm locking technique. Libraries offer procedural entry-points to the client, which are checked for a compatible interface (all parameters and return types of imported procedures checked) before the client is linked to the library. The library and its client may be written in different languages. The advantage is that all synchronization is provided in the library and client code does not need to worry about this level of programming at all. This results in robust code since clients can't undermine the synchronization code in the library. (Some would call this a '
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across several drives, as well as mirrored for recoverability of sensitive data. For added flexibility, each program can make volume substitutions, a volume name may be substituted with a primary and secondary alternate name. This is referred to as the process’ FAMILY. For instance, the assignment “FAMILY DISK = USERPACK OTHERWISE SYSPACK” stores files logically designated on volume DISK onto the volume USERPACK and will seek files first on volume USERPACK. If that search has no success, another search for the file is done on volume SYSPACK. DISK is the default volume name if none is specified.
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new versions of MCP for customers. Many customers developed niche expertise on the inner workings of the MCP, and customers often sent in the 'patches' (fragment pieces of source code with sequence numbers) as suggestions of new enhanced features or fault corrections (FTR - field trouble reports). Many of the suggested patches were included by the systems developers and integrated into the next version of the MCP release. Including a community of voluntary, self-professed experts, into mainstream technical work, is now widely practised and is the essence of
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this point, the library's stack was said to be frozen since nothing more would be run on this stack until the library became unfrozen, in which case clean-up and termination code would be run. When a client calls a routine in a library, that routine runs on top of the client stack, storing its locals and temporary variables there. This allows many clients to be running the same routine at the same time, being synchronized by the library routine, which accesses the data in the global environment of the library stack.
252:, Burroughs software only ever ran on Burroughs hardware due to a lack of compatible third party hardware. For this reason, Burroughs was free to distribute the source code of all software it sold, including the MCP, which was designed with this openness in mind. For example, upgrading required the user to recompile the system software and apply any needed local patches. At the time, this was common practice, and was necessary as it was not unusual for customers (especially large ones, such as the
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can be from 0 to 99 for user processes. System processes may be assigned the higher values. Note that this numerical priority is secondary to an overall priority, which is based on the task type. Processes that are directly part of the operating system, called
Independent Runners, have the highest priority regardless of numeric priority value. Next come processes using an MCP lock, then Message Control Systems such as
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256:) to modify the program to fit their specific needs. As a result, a Burroughs Users Group was formed, which held annual meetings and allowed users to exchange their own extensions to the OS and other parts of the system software suite. Many such extensions have found their way into the base OS code over the years, and are now available to all customers. As such, the MCP could be considered one of the earliest
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and EOJ for end of tasks and jobs. As well, all file and database open and closes can be logged. Logging many events contributes to an apparent slowness of the MCP operating environment compared to systems like Unix, since everything is logged with forced physical writes to the program log after every record, which is what systems like Unix don't do, even though they too keep many things in the system logs.
378:. Thus all processes waiting on a single resource wait on a single event. When the resource becomes available, the event is caused, which wakes up all the processes waiting on it. Processes may wait on multiple events for any one of them to happen, including a time out. Events are fully user programmable – that is, users can write systems that use the generalized event system provided by the MCP.
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force programmers to add code to check for the presence of files before accessing them, and thus extra code must be written in every case to provide recoverability, or process synchronization. Such code may be written in an MCP program when it is not desirable to have a task wait, but because of the operator-level recoverability, this is not forced and therefore makes programming much simpler.
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production environment it was found to be better to keep all files in a single directory, even though they retain the hierarchical naming scheme. Programmatically, this makes no difference. The only difference visible to users is that an entity file can have the same name as a directory. For example, "A/B" and "A/B/C" can both exist; "B" can be both a node in a file and a directory.
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system is available as a connection library, allowing other programs to use its services by exporting and importing functions. Upon linkage, each client gets a dedicated structure block to keep state information in. A program that uses the network might import a network-write function and export a network-read function. Thus, if you open a network connection (e.g., using
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is found in a table previously set up by an operator with 'SL' (system library) commands, for example 'SL system_support = *system/library/support'. MCP's fault tolerant attitude also works here – if a client tries accessing a library that is not present, the client is put in the 'waiting' tasks and the library could be made present, or the request redirected.
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faults (e.g., divide by zero) can be listed, or the catch-all 'anyfault' can be used. The statement or block following the 'ON' statement is recognized by the compiler as fault-handling code. During execution, if a recoverable fault occurs in scope of the 'on' statement, the stack is cut back and control transferred to the statement following it.
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available, CAUSE the EVENT that processes have been waiting on without further operator intervention. To pass textual information from an operator to a program, the accept command ‘3456AX MORE INFO’ can be used. Programs can pass information to operators using the DISPLAY mechanism, which causes DISPLAY messages to be added to the MSG display.
371:. Then Discontinued processes. Then Work Flow Language jobs. Finally come user processes. At a lower level, there is a Fine priority intended to elevate the priority of tasks that do not use their full processor slice. This allows an IO bound task to get processor time ahead of a processor bound task on the same declared priority.
311:). Other attributes have the file's record size (if fixed for commercial applications), the block size (in multiples of records that tells the MCP how many records to read and write in a single physical IO) and an area size in multiples of blocks, which gives the size of disk areas to be allocated as the file expands.
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The MCP was the first OS developed exclusively in a high-level language. Over its 50-year history, it has had many firsts in a commercial implementation, including virtual memory, symmetric multiprocessing, and a high-level job control language (WFL). It has long had many facilities that are only now
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An operator can force a task into the waiting entries with the stop command '3456ST' and make it active again with OK: '3456OK'. The OK command can also be used when an operator has made a resource available for a task, although more frequently than not, the MCP will detect that resources have become
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In the mid-1990s a new type of library was made available: Connection
Libraries. These are programs in their own right that can execute independently as well as import and export data and functions to other programs in arrays of structure blocks. For example, the networking component of the operating
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To accomplish such enhanced protection, a newer mechanism was introduced in the mid 1990s. In a misguided attempt at compatibility, it was named after the then-proposed C++ language construct of the same name. Because the syntax and behavior of the two differ to such a large extent, choosing the same
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If the resource cannot be provided by the operator, the operator can DS the task as a last resort. This is different from other systems, which automatically terminate a task when a resource such as a file is not available. The MCP provides this level of operator recoverability of tasks. Other systems
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Burroughs was not the first manufacturer to distribute source code and was a late entry to electronic computing (compared to its traditional rivals NCR, IBM, and Univac). Now that MCP runs on commodity hardware, some elements of the MCP based software suite are no longer made available in source form
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Tasks are entered in the program 'mix' and identified by mix numbers, as are libraries. To execute a program, operators can use the 'EX' or 'RUN' command followed by the file name of the program. ODTs are run typically with ADM (Automatic
Display Mode), which is a tailorable display of system status
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Large systems have dedicated operations terminals called ODTs (Operator
Display Terminals), usually kept in a secure environment. For small systems, machines can be controlled from any terminal (provided the terminal and user have sufficient privileges) using the MARC program (Menu Assisted Resource
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Libraries could also be accessed 'by title' and 'by function'. In 'by title' the client specified the file name of the library. 'By function' was an indirect method where a client would just specify the function name of the library, for example 'system_support' and the actual location of the library
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If this was the first invocation of the library, the library would run its main program (outer block in an ALGOL program) to initialize its global environment. Once initialization was complete, it would execute a freeze, at which point all exported entry points would be made available to clients. At
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Shared by rununit is a sharing mechanism in between these two sharing schemes. It was designed specifically for COBOL, where a rununit is defined as the original initiating client program and all the libraries it has linked to. Each rununit gets one instance of the library and different rununits get
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In addition to the ability to dynamically remap file (or database) requests to other files (or databases), before or during program execution, several mechanisms are available to allow programmers to detect and recover from errors. One way, an 'ON' statement, has been around for many years. Specific
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Running processes are those that use a processor resource and are marked as 'running'. Processes that are ready to be assigned to a processor, when there is no free processor are placed in the ready queue. Processes may be assigned a “Declared” or “Visible” priority, generally 50 as the default, but
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Files are stored on named volumes, for example 'this/is/a/filename on myvol', 'myvol' being the volume name. This is device independent, since the disk containing 'myvol' can be moved or copied to different physical disk drives. Disks can also be concatenated so that a single volume can be installed
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While the task is ALIVE, MCP functions are run on top of that particular process, thus CPU resources are automatically charged to the task causing the MCP overhead. Also, much of the MCP work is being performed with that particular stack's security rights. Only before BIRTH and after DEATH does the
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As with file attributes, tasks have attributes as well, such as the task priority (which is assigned at compile time or execution time, or can be changed while the task is running), processor time, wait time, status, etc. These task attributes can be accessed programmatically as can file attributes
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Beyond the many technical innovations in the MCP design, the
Burroughs Large Systems had many management innovations now being used by the internet community at large. The system software was shipped to customers inclusive of source code and all the editing and compilation tools needed to generate
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All actions in the system are logged, for example all messages displayed to the operator, and all operator actions. All significant program actions are optionally logged in a system log and a program log, for example BOJ for beginning of a WFL job, BOT for beginning of a task within a WFL job, EOT
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Shared by all is more interesting. When a client starts up, it can run for a while until it requires the services in the library. Upon first reference of a library entry-point, the linkage is initiated. If an instance of the library is already running, the client is then linked to that instance of
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Syntactically, 'try' statements look like 'if' statements: 'try', followed by a statement or block, followed by 'else' and another statement or block. Additional 'else' clauses may follow the first. During execution, if any recoverable termination occurs in the code following the 'try' clause, the
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Tasks waiting on a resource are listed under the waiting entries and the reason for waiting. All waiting tasks may be listed with the 'W' command. The reason for waiting is also listed and more information about a task may be seen with the 'Y' command. It may be that a task is waiting for operator
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nodes were represented by separate files with directory entries, as other systems did. However, since about 1970, MCP internally uses a 'FLAT' directory listing all file paths on a volume. This is because opening files by visiting and opening each directory in a file path was inefficient and for a
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The logs can be used for forensics to find out why programs or systems may have failed, or for detecting attempts to compromise system security. System logs are automatically closed after a system-settable period and a new one opened. System logs contain a huge amount of information, which can be
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Function libraries also implemented a very important security feature, linkage classes. All normal libraries have a linkage class of zero. Libraries used by the MCP or other privileged system modules may not be usable from normal programs. They are accessed by function and forced in linkage class
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One problem with the handling logic behind the ON statement was that it would only be invoked for program faults, not for program terminations having other causes. Over time, the need for guaranteed handling of abnormal terminations grew. In particular, a mechanism was needed to allow programs to
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An MCP Process goes through a life cycle from the time it enters the system until it leaves. The initial state for a Job is "Queued." There is a period of time while the Job resides in one of several user defined Job Queues. The next state is "Scheduled" as the Job moves from a queue into memory.
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Another security mechanism is that code files can only be created by trusted compilers. Malicious programmers cannot create a program and call it a compiler – a program could only be converted to be a compiler by an operator with sufficient privileges with the 'mc' make compiler operator command.
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Freeze could also be in three forms – temporary, permanent and controlled. Temporary meant that once the client count dropped to zero, the library would be unfrozen and terminated. Permanent meant that the library remained available for further clients even if the client count dropped to zero –
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looks at the way dependent processes could be asynchronously run so that many processes could share common data (with the mechanisms to provide synchronized update). Such a family of related processes had to be written as a single program unit, processing procedures at higher lex levels as the
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Tasks waiting on user input or file reads would not normally be listed as waiting entries for operator attention. Another reason for a task to be waiting is waiting on a file. When a process opens a file, and the file is not present, the task is placed in the waiting entries, noting that it is
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Terminated tasks are displayed as completed tasks with the reason for termination, EOT for normal 'end of task', and DSed with a reason for a process failure. All processes are assigned a mix number, and operators can use this number to identify a process to control. One such command is the DS
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The common form for software would be sources on tape or a disk pack generally you would have to recompile for your hardware from the common machine independent sources. This is in stark contrast to the common distribution of binaries only by IBM and others who generally closely guarded these
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The MCP also provides a sophisticated yet simple operator environment. For large installations, many operators might be required to make physical resources, such as printers (loading paper, toner cartridges, etc.) available. Low-end environments for small offices or single user may require an
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A task goes through various states starting with NASCENT. At DELIVERY the event BIRTH is caused and the task's state changes to ALIVE. When PROCESSKILL is called upon, the state changes into DISEASED. When DEATH is caused the task gets put into the queue structure the MORGUE, after which all
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waiting on a certain file. An operator (or the user that owns the process) has the opportunity either to copy the file to the expected place, or to redirect the task to read the file from another place, or the file might even be created by an independent process that hasn't yet completed.
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not only handle memory space, they also allocate or deallocate the disk space where non memory resident data may be overlaid. Memory may be SAVE (i.e., memory resident), OVERLAYABLE (i.e., virtual memory) or STICKY (meaning memory resident, but movable). They are called upon e.g. by
359:." A Job contains one or more tasks. Tasks within a job can run sequentially or in parallel. Logic can be implemented at the Job level, typically in the MCP's job control language WFL, to control the flow of a job. Once all tasks in a job are complete, the job itself is completed.
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Tasks within a job do not wait in queue; instead going directly to the 'Scheduled' state when initiated. Once a Job or Task is started, it can transition between "Active," "Waiting" and "Scheduled" as it progresses. Once a Job or Task completes, it moves to the 'Completed' state.
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A server listening for incoming connections declares a port file (a file with the KIND attribute equal to PORT). Each connection that is made from a client creates a subfile with an index, so each port file represents multiple connections to different clients around the network.
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Operator commands are mostly two letters (as with Unix), and some are just one letter. This means that the operator interface must be learned, but it is very efficient for experienced operators who run a large mainframe system from day to day. Commands are case insensitive.
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A server process receives client requests from anywhere on the network by issuing a read on the port file (subfile = 0 to read from any subfile). It issues a response to the client that issued the request by writing to the particular subfile from which the request was read.
628:), when data arrives for you to read, the networking component can directly call your function to consume it, without having to first copy the data to a buffer and do a context switch. Likewise, you can write data to the network by directly calling a network-write function.
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If a task becomes waiting on some operator action, the operator can find out what the task needs by entering its mix number followed by the 'Y' command. (Note the object-oriented style of commands, selecting the object first, followed by the command.) For example, '3456Y'.
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one. A client in linkage class zero cannot link to linkage class one entry-points. A library with linkage class one that needs to offer entry-points to normal programs can do so if it is designated as ‘trusted’. It can offer selected entry-points in linkage class zero.
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permanent libraries could be unfrozen by an operator with a THAW command. A controlled freeze meant that the library actually kept running, so that it could execute monitoring functions and perform data initialization and cleanup functions for each linking client.
648:, except that they are generalized to be multiway and bidirectional. Since these are an order of magnitude slower than other IPC techniques such as libraries, it is better to use other techniques where the IPC is between different processes on the same machine.
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command (which stands for either Delete from
Schedule, DiScontinue, or Deep Six, after the influence of Navy personnel on early computer projects, depending on who you talk to). Tasks terminated by the operator are listed in the complete entries as O-DS.
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Most events that would result in task termination are recoverable. This includes stack overflow, array access out-of-bounds, integer over/under flow, etc. Operator (or user) DS is not recoverable except by privileged tasks using an UNSAFE form of try.
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architecture since its inception. This scheme is unique in the industry, as it stores and retrieves compiler-defined objects rather than fixed-size memory pages, as a consequence of its overall non-von
Neumann and uniformly stack-based architecture.
588:. MCP libraries can be 'shared by all', ‘shared by rununit’ or 'private'. The private case is closest to libraries on other systems – for each client a separate copy of the library is invoked and there is no data sharing between processes.
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The DUMPANALYZER analyzes memory dumps that were originally written to tape. As all compilers added LINEINFO into the code-files, the DUMPANALYZER is able to pinpoint exactly which source statement was being executed at the time of error.
388:, the change from ready to running and back is so quick that distinguishing ready and running tasks is pointless because they will all get a slice of the processor within a second). All active tasks can be displayed with the 'A' command.
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Connection
Libraries allow a significant degree of control over linkages. Each side of a linkage can optionally approve a linkage and can sever the linkage as desired. State can be easily maintained per linkage as well as globally.
328:, providing fault tolerance in case of disk failure, loss of power, etc. It is not possible to corrupt the file system (except by the operating system or other trusted system software with direct access to its lower layers) .
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Libraries can also be updated on the fly, all that needs to be done is to 'SL' the new version. Running clients will continue to use the old version until they terminate and new clients will be directed to the new version.
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stack is cut back if required, and control branches to the code following the first 'else'. In addition, attributes are set to allow the program to determine what happened and where (including the specific line number).
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The entire database system is implemented with libraries providing very efficient and tailored access to databases shared between many clients. The same goes for all networking functionality and system intrinsics.
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The most advantageous use of port files is therefore for distributed IPC. Port files were introduced with BNA (Burroughs
Network Architecture), but with the advent of standard networking technologies such as
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The MCP was a leader in many areas, including: the first operating system to manage multiple processors, the first commercial implementation of virtual memory, and the first OS written exclusively in a
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of files. The parent task is available programmatically as a task attribute that is of type task. For example, 'myself.initiator.name' gives the name of the process that initiated the current process.
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invoke plug-ins written by customers or third parties without any risk should the plug-in behave badly. In addition to general plug-in mechanisms, the new form of dynamic library linkage (
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are the two main procedures handling memory allocation and deallocation. Memory needs to be allocated at process initiation and whenever a block is entered that uses arrays, files, etc.
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input, which is sent to a task via the accept 'AX' command (note that operator input is very different from user input, which would be input from a network device with a GUI interface).
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usually set up to display the active, waiting, and completed mix entries, as well as system messages to the operator for notifications or situations requiring operator action.
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Operationally, the status of all tasks in the system is displayed to the operator. All running and ready processes are displayed as 'Active' tasks (since the system implements
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Files are protected by the usual security access mechanisms such as public or private, or a file may have a guard file where the owner can specify complex security rules.
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As well as tasks and processes, operators also have control over files. Files can be listed using the FILE command, copied using COPY, removed using REMOVE, and renamed.
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and successors) were unique in that they were designed with the expectation that all software, including system software, would be written in an HLL rather than in
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So clean and radical was the library mechanism that much system software underwent major rewrites resulting in a better structured systems and performance boosts.
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software assets at the source level. This actually was necessary because this is the means by which the code accommodated local site differences in hardware, etc.
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is the procedure that decides which process is the next one to receive CPU resources and is thus one of the few processes that uses the MoveStack instruction.
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about a file, most importantly its name and its type (which tells the system how to handle a file, like the more limited four-character file type code on the
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The operating environment of the MCP is powerful, yet simple and usually only requires a fraction of the number of operators of other systems.
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Also a normal program dump, where just one program was dumped, contains information on source-code sequence number and variable names.
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The file type indicates if the file is character data, or source code written in particular languages, binary data, or code files.
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appearing in other widespread operating systems, and together with the
Burroughs large systems architecture, the MCP provides a
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Complete listing of these displays are given by the 'A' (active), 'W' (waiting), 'C' (completed), and 'MSG' (message commands).
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Unisys stopped producing the hardware in the early 2010s, and the operating system is now run under emulation.
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Libraries were introduced to MCP systems in the early 1980s, having been developed by Roy Guck and others at
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MCP need to be operating out of some other stack. If none is available, the system maintains an idle stack.
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asynchronous processes, which could still access global variables and other variables at lower lex levels.
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is the main security guardian of the system, called upon at process start, file open, user log on, etc.
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MCP thus provides a very fault-tolerant environment, not the crash-and-burn core-dump of other systems.
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Unisys MCP has had several generations of compilers in its history supporting a wide variety of
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unless quotes are added around the name in which case it is case-sensitive and case-preserving.
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or the like while cleaning up and releasing resources declared and used within that block.
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Tasks can also terminate due to program faults, marked as F-DS or P-DS, for faults such as
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Each file in the system has a set of file attributes. These attributes record all sorts of
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Processes that are waiting on other resources, such as a file read, wait on the EVENT
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86001047-515.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86000304-307.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86000544-103.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86000080-103.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86002003-407.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/39576053-003.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86001518-316.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86000296-209.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86002268-206.pdf
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http://public.support.unisys.com/aseries/docs/clearpath-mcp-17.0/pdf/86000098-515.pdf
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209:(Executive Systems Problem Oriented Language). In the 1970s, MCP was converted to
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a different instance. This is the only dynamic implementation of COBOL rununits.
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Libraries and independent processes are written as independent programming units
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753:. This management innovation of community development dated back to the 1970s.
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Libraries are more sophisticated forms of libraries on other systems such as
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remaining resources are freed to the system by a process called PROCESSKILL.
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Libraries completely inverted this scenario with the following advantages:
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which was a better structured, more robust, and more secure form of ESPOL.
876:"ClearPath MCP Software: Software Release Announcement ClearPath MCP 20.0"
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Control). Operator commands can also be used by users familiar with them.
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provide a way of sharing data and code between processes. The article on
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The two analyzers are major diagnostic tools for all kinds of purposes.
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with hierarchical directory structures. In early MCP implementations,
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is called upon by a task exiting a block. BLOCKEXIT may in turn call
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Report Program Generator (RPG) Programming Reference Manual Volume 1
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Unlike IBM, which faced hardware competition after the departure of
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An important part of the operations environment is the high-level
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operator-free environment (especially the laptop implementation).
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Libraries completely controlled access to shared resources (data
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Burroughs B6700/B7700 System software handbook (form no 5000722)
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Libraries and clients could be written in different languages
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In 1961, the MCP was the first OS written exclusively in a
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There is no assembler on the Unisys MCP operating system.
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filtered and analyzed with programs such as LOGANALYZER.
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Process switching was not required to safely access data
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Processes that have terminated are marked as completed.
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when a process addresses an uninitialized array or by
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245:, which was a unique and innovative approach in 1961.
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Work Flow Language (WFL) Programming Reference Manual
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name has only led to confusion and misunderstanding.
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COBOL ANSI-85 Programming Reference Manual Volume 1
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COBOL ANSI-74 Programming Reference Manual Volume 1
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65:
49:
592:the library. All clients share the same instance.
267:The MCP was the first commercial OS to provide
479:handles hardware interrupts and may call upon
1140:
8:
1038:Pascal Programming Reference Manual Volume 1
44:
942:ALGOL Programming Reference Manual Volume 1
772:, including DCALGOL, BDMSALGOL and DMALGOL.
1147:
1133:
1125:
43:
958:C Programming Reference Manual Volume 1
867:
1433:Computer-related introductions in 1961
1006:Fortran77 Programming Reference Manual
904:"Burroughs B5000 Information Brochure"
205:MCP was originally written in 1961 in
1203:Compatible Time-Sharing System (CTSS)
7:
1070:Binder Programming Reference Manual
27:Mainframe computer operating system
1097:. (Unisys publication 8600 1047).
1072:. (Unisys publication 8600 0304).
1056:. (Unisys publication 8600 0544).
1040:. (Unisys publication 8600 0080).
1024:. (Unisys publication 8600 2003).
1008:. (Unisys publication 3957 6053).
992:. (Unisys publication 8600 1518).
976:. (Unisys publication 8600 0296).
960:. (Unisys publication 8600 2268).
944:. (Unisys publication 8600 0098).
783:which includes COBOL74 and COBOL85
271:, which has been supported by the
134:including the Unisys Clearpath/MCP
25:
1022:NEWP Programming Reference Manual
825:Compilers previously existed for
642:inter-process communication (IPC)
525:Software components and libraries
1381:
1380:
180:(Master Control Program) is the
18:Unisys MCP programming languages
1218:Cray Time Sharing System (CTSS)
1418:Time-sharing operating systems
1:
1413:Proprietary operating systems
1408:Burroughs mainframe computers
1170:Time-sharing system evolution
644:is port files. They are like
1188:Berkeley Timesharing System
1093:Unisys Corporation (2009).
1068:Unisys Corporation (2009).
1052:Unisys Corporation (2008).
1036:Unisys Corporation (2009).
1020:Unisys Corporation (2008).
1004:Unisys Corporation (2008).
988:Unisys Corporation (2009).
972:Unisys Corporation (2008).
956:Unisys Corporation (2008).
940:Unisys Corporation (2008).
815:Network Definition Language
105:; 63 years ago
1449:
829:, COBOL(68), Fortran(66),
573:. They are very much like
29:
1376:
1178:
1165:
1423:Unisys operating systems
807:Other products include:
32:Master Control Program (
1183:BBN Time-Sharing System
535:Burroughs large systems
386:preemptive multitasking
273:Burroughs large systems
132:Burroughs large systems
1114:MCP 19.0 Documentation
640:Another technique for
326:Journaling file system
235:Burroughs Large System
763:programming languages
676:Operating environment
324:The MCP implements a
425:Connection Libraries
193:B6500 and successors
928:"The Mainframe Six"
331:The file system is
287:The MCP provides a
231:high-level language
219:high-level language
147:Text user interface
46:
820:Work Flow Language
715:Work Flow Language
343:Process management
1395:
1394:
1159:operating systems
579:Trusted Computing
477:HARDWAREINTERRUPT
467:HARDWAREINTERRUPT
243:assembly language
189:B5000/B5500/B5700
174:
173:
16:(Redirected from
1440:
1384:
1383:
1283:ORVYL and WYLBUR
1149:
1142:
1135:
1126:
1120:Unisys ClearPath
1101:
1091:
1085:
1082:
1076:
1066:
1060:
1050:
1044:
1034:
1028:
1018:
1012:
1002:
996:
986:
980:
970:
964:
954:
948:
938:
932:
931:
924:
918:
914:
908:
907:
900:
894:
893:
891:
890:
880:
872:
857:
512:
500:
496:
492:
486:
482:
478:
472:
468:
463:
459:
455:
451:
401:numeric overflow
333:case-insensitive
195:, including the
182:operating system
169:Unisys ClearPath
165:Official website
113:
111:
106:
94:Source available
47:
41:Operating system
21:
1448:
1447:
1443:
1442:
1441:
1439:
1438:
1437:
1398:
1397:
1396:
1391:
1372:
1174:
1161:
1153:
1110:
1105:
1104:
1092:
1088:
1083:
1079:
1067:
1063:
1051:
1047:
1035:
1031:
1019:
1015:
1003:
999:
987:
983:
971:
967:
955:
951:
939:
935:
926:
925:
921:
915:
911:
902:
901:
897:
888:
886:
878:
874:
873:
869:
864:
855:
851:
843:
759:
751:open innovation
746:
723:
678:
638:
527:
510:
498:
494:
490:
484:
480:
476:
470:
466:
461:
457:
453:
449:
345:
337:case-preserving
285:
254:Federal Reserve
227:
141:
123:20.0 / May 2021
109:
107:
104:
100:Initial release
42:
39:
28:
23:
22:
15:
12:
11:
5:
1446:
1444:
1436:
1435:
1430:
1425:
1420:
1415:
1410:
1400:
1399:
1393:
1392:
1390:
1389:
1377:
1374:
1373:
1371:
1370:
1365:
1360:
1355:
1350:
1345:
1340:
1335:
1330:
1325:
1320:
1315:
1310:
1305:
1300:
1295:
1290:
1285:
1280:
1275:
1270:
1265:
1260:
1255:
1250:
1245:
1240:
1235:
1230:
1225:
1220:
1215:
1210:
1205:
1200:
1195:
1190:
1185:
1179:
1176:
1175:
1173:
1172:
1166:
1163:
1162:
1154:
1152:
1151:
1144:
1137:
1129:
1123:
1122:
1117:
1109:
1108:External links
1106:
1103:
1102:
1086:
1077:
1061:
1045:
1029:
1013:
997:
981:
965:
949:
933:
919:
909:
895:
866:
865:
863:
860:
850:
847:
842:
839:
823:
822:
817:
812:
805:
804:
799:
794:
789:
784:
778:
773:
758:
755:
745:
742:
722:
719:
677:
674:
637:
634:
581:Initiative'.)
575:C. A. R. Hoare
564:
563:
560:
557:
546:
526:
523:
505:J_EDGAR_HOOVER
376:data structure
344:
341:
284:
281:
269:virtual memory
226:
223:
172:
171:
166:
162:
161:
156:
150:
149:
144:
142:user interface
136:
135:
129:
125:
124:
121:
119:Latest release
115:
114:
101:
97:
96:
91:
87:
86:
83:
79:
78:
69:
63:
62:
53:
40:
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1445:
1434:
1431:
1429:
1428:1961 software
1426:
1424:
1421:
1419:
1416:
1414:
1411:
1409:
1406:
1405:
1403:
1388:
1379:
1378:
1375:
1369:
1366:
1364:
1361:
1359:
1356:
1354:
1351:
1349:
1346:
1344:
1341:
1339:
1336:
1334:
1331:
1329:
1326:
1324:
1321:
1319:
1316:
1314:
1311:
1309:
1306:
1304:
1301:
1299:
1296:
1294:
1291:
1289:
1286:
1284:
1281:
1279:
1276:
1274:
1271:
1269:
1266:
1264:
1261:
1259:
1256:
1254:
1251:
1249:
1246:
1244:
1241:
1239:
1236:
1234:
1231:
1229:
1226:
1224:
1221:
1219:
1216:
1214:
1211:
1209:
1206:
1204:
1201:
1199:
1196:
1194:
1193:Burroughs MCP
1191:
1189:
1186:
1184:
1181:
1180:
1177:
1171:
1168:
1167:
1164:
1160:
1157:
1150:
1145:
1143:
1138:
1136:
1131:
1130:
1127:
1121:
1118:
1115:
1112:
1111:
1107:
1100:
1096:
1090:
1087:
1081:
1078:
1075:
1071:
1065:
1062:
1059:
1055:
1049:
1046:
1043:
1039:
1033:
1030:
1027:
1023:
1017:
1014:
1011:
1007:
1001:
998:
995:
991:
985:
982:
979:
975:
969:
966:
963:
959:
953:
950:
947:
943:
937:
934:
929:
923:
920:
913:
910:
905:
899:
896:
884:
877:
871:
868:
861:
859:
848:
846:
840:
838:
836:
832:
828:
821:
818:
816:
813:
810:
809:
808:
803:
800:
798:
795:
793:
790:
788:
785:
782:
779:
777:
774:
771:
768:
767:
766:
765:, including:
764:
756:
754:
752:
743:
741:
738:
735:
731:
727:
720:
718:
716:
711:
708:
705:
701:
697:
694:
690:
686:
682:
675:
673:
669:
665:
663:
659:
655:
649:
647:
643:
635:
633:
629:
627:
621:
617:
613:
609:
605:
601:
597:
593:
589:
587:
582:
580:
576:
572:
567:
561:
558:
555:
551:
550:encapsulation
547:
544:
543:
542:
539:
536:
532:
524:
522:
518:
514:
508:
506:
502:
488:
487:or the like.
474:
447:
443:
440:
436:
432:
428:
426:
420:
416:
412:
408:
404:
402:
398:
397:invalid index
393:
389:
387:
382:
379:
377:
372:
370:
364:
360:
358:
354:
350:
342:
340:
338:
334:
329:
327:
322:
318:
315:
312:
310:
306:
301:
297:
294:
290:
282:
280:
277:
274:
270:
265:
261:
259:
255:
251:
246:
244:
240:
236:
232:
224:
222:
220:
214:
212:
208:
203:
201:
200:Clearpath/MCP
198:
194:
190:
187:
183:
179:
170:
167:
163:
160:
157:
155:
151:
148:
145:
143:
137:
133:
130:
126:
122:
120:
116:
102:
98:
95:
92:
88:
84:
82:Working state
80:
77:
73:
70:
68:
64:
61:
57:
54:
52:
48:
37:
35:
19:
1192:
1156:Time-sharing
1094:
1089:
1080:
1069:
1064:
1053:
1048:
1037:
1032:
1021:
1016:
1005:
1000:
989:
984:
973:
968:
957:
952:
941:
936:
922:
912:
898:
887:. Retrieved
870:
852:
844:
824:
806:
760:
747:
739:
736:
732:
728:
724:
712:
709:
706:
702:
698:
695:
691:
687:
683:
679:
670:
666:
650:
639:
630:
622:
618:
614:
610:
606:
602:
598:
594:
590:
583:
568:
565:
540:
528:
519:
515:
509:
503:
489:
475:
448:
444:
441:
437:
433:
429:
421:
417:
413:
409:
405:
394:
390:
383:
380:
373:
365:
361:
351:are called "
346:
330:
323:
319:
316:
313:
302:
298:
286:
278:
266:
262:
247:
228:
215:
204:
199:
177:
175:
90:Source model
33:
856:very secure
744:Innovations
499:FORGETSPACE
462:FORGETSPACE
454:FORGETSPACE
289:file system
283:File system
264:by Unisys.
258:open-source
250:Gene Amdahl
233:(HLL). The
159:Proprietary
1402:Categories
1198:CDC Kronos
889:2021-08-14
885:. May 2021
862:References
646:Unix pipes
636:Port files
260:projects.
67:Written in
841:Assembler
787:Fortran77
757:Compilers
571:Burroughs
531:libraries
495:FILECLOSE
491:BLOCKEXIT
485:IO_FINISH
349:processes
309:Macintosh
305:meta data
293:directory
202:systems.
186:Burroughs
128:Platforms
56:Burroughs
51:Developer
1387:Category
1258:MUSIC/SP
481:GETSPACE
471:FILEOPEN
458:GETSPACE
450:GETSPACE
335:and not
191:and the
1328:TOPS-20
1323:TOPS-10
1278:OpenVMS
1253:Multics
849:Summary
721:Logging
355:" and "
225:History
184:of the
154:License
140:Default
108: (
85:Current
1385:
1363:VPS/VM
1358:VP/CSS
1303:RSTS/E
1288:OS4000
1273:NOS/VE
1213:CP/CMS
883:Unisys
833:, and
811:Binder
797:Pascal
554:hiding
511:GEORGE
197:Unisys
60:Unisys
1368:WAITS
1338:TSS/8
1308:TENEX
1263:NLTSS
1243:MCTSS
879:(PDF)
827:ESPOL
781:COBOL
770:ALGOL
369:CANDE
357:Tasks
239:B5000
207:ESPOL
72:ESPOL
1343:Unix
1318:TSOS
1293:Pick
1238:LTSS
1228:EMAS
1223:DTSS
835:PL/I
792:NEWP
656:and
586:DLLs
552:and
529:MCP
460:and
452:and
353:Jobs
347:MCP
211:NEWP
176:The
110:1961
103:1961
76:NEWP
34:Tron
1348:UTS
1333:TSS
1313:TSO
1298:RAX
1268:NOS
1248:MTS
1233:ITS
1208:COS
831:APL
802:RPG
658:TCP
654:OSI
626:TCP
178:MCP
45:MCP
1404::
1353:VM
881:.
837:.
717:.
662:IP
497:,
483:,
473:.
399:,
221:.
74:,
58:/
1148:e
1141:t
1134:v
930:.
906:.
892:.
776:C
660:/
556:)
237:(
112:)
38:.
36:)
20:)
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